diesel electric sailboat

Propulsion Systems for Monohull

The silence of an Oceanvolt electric propulsion is a skipper's dream.  Whether quietly maneuvering through a harbor or motor-sailing on low-wind days to create your own apparent wind, our electric solutions will enhance and extend your sailing enjoyment. 

Oceanvolt offers Hybrid or Electric systems as a power & propulsion option in partnership with many leading monohull boat builders - adding new partners continuously. We also offer repowering solutions for converting away from legacy diesel engines – removing the diesel engine, fuel tanks and exhaust system - cleaning up greasy, smelly engine compartments and freeing up both weight and space below deck.

Oceanvolt systems are scaled and configured to achieve maximum efficiency - taking into consideration boat length, beam and displacement as well as system weight and placement within the boat.  Range, beyond battery capacity, is extended through hydro generation while sailing above 6kn.  This can be complemented with either a portable AC generator or a DC generator (in larger boats or for long distance cruising).

All Oceanvolt systems are engineered to operate at 48 volts for passenger safety and ease of repair. Oceanvolt systems are extremely low maintenance and do not require winterizing (no annual engine maintenance/storage costs).

system & price examples

Owner testimonials.

Electric Beneteau Oceanis 40.1 “Moritz”

Maxi Dolphin MD55

RM Yachts RM 1180

Yachting Monthly

• Digital edition

Electric yacht: What are the options for going electric?

• Will Bruton
• July 17, 2020

The options for having an electric yacht or a hybrid-electric yacht are growing in popularity; we outline the current options for those making the switch

The Arcona 380Z is a standard production yacht that has been adapted for electric propulsion. Note the increased solar panel surface area with soft panels bonded to the sails. Credit: Jukka Pakainen

A modern electric yacht can come in all shapes and sizes, from the latest high-tech speed boats with recently developed high-performance electric engines, to a traditional tender with an electric outboard on the back. Increasingly yachts are going electric too as electric engines become increasingly capable of propelling boats weighing several tonnes, and with the rigging for sails, at a reasonable speed for an acceptable length of time. 

Since the invention of the marinised engine , there has never been the capacity to store enough fuel to cover significant distances in boats that are smaller than a tanker, with fuel capacity always being the limiting factor. As such the best way to cover long distances on a boat fit for a small number of passengers was, and remains, wind power. 

For all the many green attributes that using the power of wind offers, there is no escaping that for most, fossil fuels still represent some part of sailing – whether that be a diesel engine to motor in light winds, onto and off a mooring , or to generate power for onboard electronic systems. Even a small tender used to go from ship-to-shore is often fitted with an outboard motor.

Recent advances in electric power, however, have started to make electric propulsion a reasonable alternative to fossil fuel power. Range will always be an issue but that has long been true of a traditional diesel engine. Improvements in lithuim-ion battery performance is, and likely will continue to, increase range every year. 

Spirit Yachts 44e – the ‘e’ stands for electric

Additionally electric power and batteries offer the bonus of being able to be recharged via solar panels , a wind turbine or hydroelectric power – via a hydrogenerator mounted on the stern of a boat sailing. 

At first glance the electric yacht market could appear in its infancy, but like every revolution, the will of the people is driving forward technology that only a few years ago was seen as the stuff of fantasy.

The market has responded to demand, and battery and motor technology has come on leaps and bounds, driven in part by the rapid development of electric cars.

It may not be commonplace yet, but electric yachting is here, even available ‘off the shelf’, so is it time to get onboard?

The Spirit 111 is a bold hybrid yacht, promising 30 miles motoring under electric power alone. Credit: Ian Roman/Waterline Media

A cutting edge electric yacht

Like Formula One, it’s the cutting edge of electric yachting that trickles down into mainstream production in no time at all.

For Spirit Yachts, a builder defined by a unique blend of traditional and state-of-the-art, electric yachting has been driven by demanding clients that want their yachts to be at the cutting edge.

Spirit Yachts have now produced a number of projects aimed at the all electric luxury yacht market including the Spirit 44e electric yacht and a recent project, the Spirit 111, had all the hallmarks of a superyacht project and the team had to earn their keep delivering to brief.

Managing Director Nigel Stuart explained how it works.

‘The 111 combines several cutting-edge technologies to deliver a something that’s never really been done before. A lithium-ion powered electric drive system can be charged by hydrogenation and also two high-wattage diesel generators.

‘Each generator is 22kw, meaning they can pack a lot of power into the system in a short period of time, they don’t need to run for long to fully recharge.

‘The prop is both a means of drive and power generation, so no separate hydrogenerator is needed. She will be capable of motoring under electric alone for more than 30 miles.

‘When you take on a project that’s electric, it makes you think hard about efficiency so the air conditioning, water heaters and everything in the galley has also been carefully selected to use less power.

‘For her owner there is very little compromise and some major advantages.’

Whilst it’s a long way from the average cruising yacht, the trickle-down effect of projects like the Spirit 111 can’t be underestimated.

Calypso , a Contessa 32, was the yard’s first foray into electric-powered yachts. Credit: Jeremy Rogers

Traditional electric yacht

Jeremy Rogers’ yard in Lymington is the birthplace of the iconic Contessa designs and a veritable temple to long keeled , traditional craft.

Less well known is the yard’s interest in electric auxiliary engines, something they have been involved in for more than 10 years.

Their first project, the refit of a Contessa 32 called Calypso, was an experiment by the Rogers family to see what was possible.

‘ Calypso was a test bed in the technology’s infancy,’ explains Kit Rogers of this early electric boat.

‘Inevitably, we didn’t get it all right, but we learned a lot about the dos and don’ts of electric yachting. The end result was a hybrid. The more we did, the more interesting the project became.

‘It’s not just the obvious, silent peaceful propulsion; it’s also the things you take for granted about a cruising boat. For example, no gas, we didn’t need it because we had electric power.

The yard has also worked on an electric folkboat conversion for a foreign customer.

‘The client, first and foremost, loves to sail. He sees the electric as an auxiliary option, along with the rowing and is excited to own a boat that’s quietly different.

‘He’s looking for a more connected experience and an electric boat helps him achieve it. When you’ve been motoring in and out of marinas under chugging diesel engines for years, the electric motor is something of a revelation.

Arcona has installed solar sails on its latest 380Z electric yacht

Off-the-shelf electric yacht

Perhaps the biggest indication of the future of the electric boat is the willingness of production and semi-production builders to pin their flags to the mast and embrace it.

One of the first was Hanse, who developed a version of their 315 utilising a Torquedo electric pod system.

Providing around the same amount of power as a 10 horsepower diesel, a 4.4kWh lithium ion battery pack powers the system.

Arcona, Dufour, Elan and Delphia also have electric boat models and are each taking their own direction on entering the market.

Arcona’s 380Z (the ‘Z’ stands for ‘zero emission’) fully electric boat has solar panel covered sails, capitalising on the large surface area to top up batteries under sail.

In the multihull market, there is even more scope for solar, wind and hydrogenation due to the horizontal surface area available for solar charging.

What are the options for an electric yacht?

Pure electric.

Purely electric systems can be broadly divided into two categories, high and low voltage.

The latter is the simplest option in terms of how it works and requires less specialist knowledge to install.

Kit Rogers installed a 48v Ocean Volt system in his latest project and remarked on the experience.

‘The advantage of the low voltage system is its inherent lack of complexity. Whilst we’ve coupled it with lithium ion battery technology, it can also be wired up to conventional lead acid batteries. There are pros and cons to both. What surprises everyone is the size, it’s a tiny motor and is surrounded by lots of space where the engine would normally sit.’

High voltage systems are more advanced, and utilising lithium-ion technology, their capacity is improving year on year.

For larger yachts this is generally seen as a better option.

A partnership between BMW and Torqueedo has led to the development of the Deep Blue 315v high voltage battery.

Effectively the same unit as found in the BMWi3 electric cars now often seen on the high street, the system produces a lot of power and is being used on the Spirit 111 project as well as catamarans.

Electric hybrid

One big barrier to entry exists for most potential electric yacht buyers – range.

Even the most advanced set-ups are limited to a maximum of a few hours motoring at cruising speed.

‘The electric motors excel at two things in particular,’ explained Kit Rogers.

‘The first is as auxiliary power for getting in and out of marinas. The second is engaged at low power to very efficiently motor-sail in light airs. If you want to do more than that, at present, you need to add a way of packing in the charge into the battery quickly whilst at sea; which means a generator’ .

As with electric cars and as enthusiasm builds for the technology, a hybrid option, pairing a generator with an electric drive system, is already proving popular and is probably the most practical option for those planning to cruise any distance.

Using a large generator, charge can be quickly put into the system when needed.

Once under sail, the yacht’s propeller becomes a hydro generator, meaning that diesel power is not needed day-to-day.

Solar can also be used to add additional charging capacity.

‘When a fully integrated electric hybrid system is incorporated into a cruising yacht from the outset, its possibilities really become clear,’ explains John Arnold, UK manager at Torqeedo.

‘Sailing for days on end with no engine noise is entirely possible. There are other less obvious benefits too. Electric drives have no long rotating shaft, so can be used as pod drives as well, meaning the boat is far more manoeuvrable than even a yacht equipped with bow and stern thrusters.’

Spirit Yachts 44e

How much does it cost to convert a yacht to electric power?

The technology exists, but anyone seriously considering going electric will want to crunch the numbers.

In the case of taking out a traditional inboard diesel and replacing it with an electric system, it’s relatively easy to work this out.

However, unless you include an auxiliary generator, you will be limited to battery range alone.

For this reason, we’ve done a like for like comparison for a 35ft yacht engine refit, including the cost of a generator to make the system a practical hybrid.

Unsurprisingly, at the moment, there’s a big difference in cost, but at between three to six times the cost, it is gradually coming into the realms of possibility, and prices should continue to drop as technology develops and evolves.

Ocean Volt SD10 Motor system (including batteries, charger and 6kw generator): £30,825.16

Beta Marine Beta 20hp Marine Diesel: £4,100

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• Systems & Propulsion

Electric and Hybrid Propulsion for Sailboats

Practical sailor looks at the players in the developing field of electric auxiliary engines.

How soon will electric auxiliary propulsion be available to everyman? That depends on whom you ask. Opinions differ widely not just on what type of drive system might surge to the forefront, but even on whether the concept itself is viable. While a handful of companies forge ahead, notably Glacier Bay and Electric Marine Propulsion on this side of the Atlantic, some expected participants are waiting on the sidelines.

Photos courtesy of Manufacturers

One of the big issues that divides promoters and detractors alike is whether the appropriate way to go in a sailboat is with a pure diesel-electric drive train, with a hybrid electric drive with a diesel generator as back-up, or as a pure electric drive with regeneration capability. We’ll take a look at these and other options later in this article. For now, the short answer is that no single approach suits every sailor all the time.

Simply put, in the diesel-electric system, the electric motor runs only when the diesel-driven generator is running. Such arrangements have long been employed in railway locomotives, submarines, and commercial vessels of many types. In the hybrid system, a large bank of batteries provides the energy for the electric motor and the diesel generator recharges the batteries. On the face of it, the hybrid system offers a certain degree of redundancy in that, assuming the batteries are kept well charged, the boat has a measure of emergency power should the generator fail at an inopportune moment. The hybrid also is capable of recharging its batteries when sailing: Driven by the turning propeller, the motor becomes a generator.

Each of these approaches has its strengths and weaknesses, and while we’ll leave it to their developers to work out the technical issues, we would like to urge anyone contemplating installing an electric drive, or purchasing a boat that has one, to first look very closely at how they expect to use the boat. There’s more entrained in the choice than in picking a flavor at Baskin-Robbins. More on this later.

Among the electric drives currently available in one form or another, or as components, the big variable is operating voltage. Motors are available that run on 24, 36, 48, 72, and 144 volts, and, in the case of Glacier Bay’s diesel-electric system with Ossa Powerlite technology, 240-volt DC. Each supplier will discourse at length on the merits of their voltage choice, but an inconvenient fact haunts the entire field: High-voltage DC is deadly, potentially more so in some circumstances than AC.

While neither form of high-voltage is “safe,” we have a lot more experience with AC aboard recreational vessels than with high-voltage DC. An extensive body of knowledge exists on which to base AC installations so as to make them safe as well as reliable. High-voltage DC is used in a variety of marine and non-marine commercial applications, but these installations are well protected from access by untrained operators.

What voltage constitutes high voltage? That, again, depends on whom you talk to. The American Boat & Yacht Council (ABYC), which sets voluntary standards for the marine industry, defines it as 50 volts and above. Prompted by rapid adoption of high-voltage services in small commercial craft and bigger yachts, though not specifically in propulsion systems, the ABYC is in the process of drawing up guidelines for voltages higher than the 48 volts covered by existing standards.

An absence of standards might not deter individuals from installing an electric drive, but it might impede widespread adoption of the technology. If a surveyor can’t state in an insurance survey that a boat is built according to ABYC standards, that could affect its insurability.

Jim Nolan, who manages the underwriting department for BoatUS, said the company has no clear cut guidance regarding insuring boats with electric propulsion. Each boat is dealt with on a case-by-case basis. A new boat with a factory-installed system would be a good deal easier to underwrite than a one-off or do-it-yourself project, especially in the absence of a standard practice. Lagoon Catamarans’ 72-volt-DC hybrid system, for instance, has qualified for the European standard (CE) certification on the strength of following industrial standards that apply to such applications as fork-lift trucks. Anyone contemplating an electric drive would be well advised to discuss it ahead of time with an insurer and even get a surveyor involved from the outset.

Because of the safety issues surrounding the voltages involved in electric propulsion, Fischer Panda has decided to limit its DC product line to boats weighing 10 tons or less. A company representative we spoke to said that while Fischer Panda currently sells DC generators up to 48 volts in the USA for marine use, it “won’t touch” high-voltage DC because it’s lethal.

A proposed collaboration with Catalina Yachts to fit a diesel-electric system in a Catalina-Morgan 440 never came to fruition due to budget constraints, according to Fischer Panda. But in Europe, Fischer Panda teamed up with Whisperprop to equip a Bavaria 49. (Beyond the fact that one of its boats was used, Bavaria Yachts was not involved in the project.) According to Fischer Panda, after evaluating the Bavaria project, the company decided that the diesel-electric AC system is a niche product that wouldn’t interest their prime market: original equipment builders.

“Although the AC system has some advantages in the improved response of the electric motors … and the quietness of the system, the desired fuel efficiency and weight savings were not evident,” Fischer Panda reported.

Fischer Panda considers the DC system to be more suitable for its North American customers. Although it’s limited in output due to its limited battery voltage of 48 volts, it is still able to power multihulls up to 10 tons.

Currently, much of the movement toward electric drives is taking place in the catamaran world. This makes sense when you consider that a single diesel generator can, in theory, provide all the boat’s electrical needs and also take the place of two diesel-propulsion engines. Taking the lead in the field, Lagoon Catamarans introduced in 2006 the Lagoon 420. Originally offered only as a hybrid, it now is also available in two diesel versions. Corsair Marine is building the Corsair 50 catamaran around the Glacier Bay diesel-electric drive, but the boat’s launch date—formerly set for this summer—has been postponed.

Dick Vermeulen, president of Maine Cat, tried the Glacier Bay system in a prototype power cat, but it failed to meet performance expectations, so production models will have conventional diesels. A number of other cat builders have announced hybrid or diesel-electric projects, but feedback on how they perform is scan’t.

So much for the mainstream—but backwater sailors will go their own way, as they always have. As more vendors and components enter the market, the options for do-it-yourselfers or custom-boat customers become broader and more attractive. However, before going ahead with an installation, make sure it’s appropriate to how you plan to use your boat, and even then be prepared to adapt the way you sail to take best advantage of the system’s characteristics. Here’s a rundown of the various types.

Electric Drive Only

Duffy Electric Boats has for years been building electric launches and lake boats that have the simple capability of puttering around in sheltered waters for a period of time determined by battery capacity and speed maintained. A battery charger powered by shore power charges the batteries overnight. Transferring that approach to a sailboat up to about 25 feet used for daysailing and kept near an electrical outlet shouldn’t be too difficult. It won’t offer the assurance of diesel when trying to get home against current or wind, but a proven 36- or 48-volt system will keep you out of uncharted standards territory.

For a bigger boat, more power, a greater range, or a combination of these requirements, it will be necessary to install a large battery bank and almost certainly will entail going to a higher voltage to keep the amps and the cabling needed to carry them manageable. The boat’s range under power will be limited by the weight of batteries, and while lighter lithium-based technology is on the horizon, for now the standard is lead/acid. The fast charging, but expensive pure lead thin plate (PLTP) Odyssey batteries have attracted particular interest among propulsion enthusiasts.

Electric Drive with Regeneration

The next level up in complexity is a “reversible” system. When the boat is sailing, the propeller turns the motor, which then becomes a generator. The electricity it makes is used to recharge the batteries. The capability to regenerate extends the boat’s potential range, but the drag on the propeller slows the boat measurably. One hour of regen will not restore the power consumed by one hour of motoring, but if sailing time sufficiently exceeds motoring time, this arrangement offers considerable range.

A regenerating system does have the potential to overcharge the batteries once they become fully charged and the boat continues to sail fast. The solution is, ironically, to give the motor some “throttle,” which reduces the drag on the propeller and consequently the power output. This phenomenon gives rise to a new technique, that of “electro-sailing” in which sails and an electric motor complement each other. At present, the “throttle” must be adjusted by hand, but developers are working on automatic controls. Field trials of existing regen motors such as the Solomon systems suggest that a small regen motor’s ability to match the output of a much higher-rated diesel have been overstated.

Hybrid Electric Drive

A hybrid system adds to the mix an onboard generator, which is used primarily to maintain charge in the batteries, both those for the propulsion motor and for the house services. This arrangement extends the boat’s capability to lie for long periods at anchor, independent of shore power for electricity and without the need to go sailing for the sole purpose of charging the batteries. A hybrid can motor constantly, as long as there is fuel, but it cannot sustain full speed for long periods. This is because the generator is usually rated at a far lower horsepower than that required to drive the boat at full speed.

Diesel-Electric Drive

In a pure diesel-electric, the electric propulsion motor runs only when the generator is running. Storage batteries are not needed for propulsion purposes, and the generator is the source for all onboard electrical power needs. The rationale behind diesel electric lies in the relationship between a diesel engine’s rate of fuel consumption and the load it’s working under. It burns fuel more efficiently when heavily loaded than when lightly loaded. When the diesel engine is disconnected from the propeller, it can be controlled so that it is working in the upper range of its efficiency regardless of how fast the propeller is turning. Nigel Calder’s series of articles in Professional Boatbuilder magazine (www.boatbuilder.com) beginning with the June/July issue delves deeply into the efficiency discussion surrounding these engines. Systems on large vessels are built around multiple generators that switch on or off according to the power demands of the moment. Translating those efficiencies into a smaller boat scenario has proven to be challenging.

Hype vs. Experience

Maine Cat’s Vermeulen, on the company’s website, describes the sea trials he performed in the Maine Cat 45, a power catamaran. He began with a Glacier Bay diesel-electric system with two 25-kW generators, each weighing about 550 pounds.

“With both generators putting out their full power of 25 kW each … our top speed was a disappointing 8.4 knots, and the assumption that electric horsepower was somehow more powerful than conventionally produced horsepower was in serious doubt.”

He replaced the propellers with a pair with less pitch, which allowed the electric motors to reach their full rating of 1,100 rpm, but that only increased the speed to 9.1 knots.

“These are about the same speeds and fuel burns we get on our Maine Cat 41 sailing cat … powered by twin 29-horsepower 3YM30 Yanmar diesels with saildrives and two-bladed, folding propellers.” At the time he installed them, the 25-kW generators were the highest power available from Glacier Bay.

Vermeulen replaced the diesel-electric system with twin 160-horsepower Volvo diesels. At 9.1 knots, they together burned 2.2 gallons per hour, considerably less than the 3 gallons per hour that the Glacier Bay system burned at the same speed. With the twin Volvos maxed out at 3,900 rpm, the boat made 24.5 knots.

Also among the unconvinced is Chris White, well-known designer of ocean-going catamarans. “To date, I’ve not seen any system that makes sense for a cruising boat,” he says, but he might change his mind, “if someone can show me by building one that delivers an advantage in performance, weight, or cost.”

White sees the current bubble of interest in diesel-electric drives as a fad. In the end, he says, you’re getting the horsepower the diesel creates at the crankshaft, which is basically the same whether it’s delivered to the prop via a conventional reduction gearbox or via a generator and an electric motor. Besides, he says, diesel engines and diesel fuel are understood and available anywhere in the world you might take a sailboat. Complex, electronically controlled electric motors are not.

White’s reservations notwithstanding, it’s in the world of catamarans that we’re seeing most of the applications. At first sight, it does seem logical that replacing three diesel engines—two propulsion and one generator—on a fully equipped cruising cat would result in fuel savings. Still, if the generator is big enough to drive the boat at cruising speed (which in a cat is expected to be in the vicinity of 10 knots) and run the air conditioning at the same time, it will be overkill for the times it’s only needed to operate the boat’s services. For this reason, commercial and military diesel-electric systems employ multiple generators that can be switched on and off according to the power demand of the moment.

Corsair Marine hopes that by installing a diesel-electric system in its 50-foot catamaran, it will be able to descend the weight spiral. Where a conventional installation would involve two 75-horsepower saildrives plus a 6-kW genset, it’s fitting a pair of 28-horsepower electric motors, one 25-kW generator, and a 40-amp, 230-volt battery bank. It expects to save about 700 pounds in equipment weight, some of it through the use of high-voltage, low-current systems, which will in turn reduce the rig requirement, thus the structural weight, and so on toward an estimated overall weight savings in the thousands of pounds.

Corsair’s David Renouf estimates that the boat will cruise at 8 knots and be capable of short bursts at 10. He admits that, until the first boat is launched, his information is “based on extrapolation, not proven numbers.” He says that some clients will add a second 25-kW genset to assure longer periods at 10 knots. Currently, the project is running behind schedule, with a launch scheduled before the end of the year.

Cost and Other Benefits

At the present time, there appears to be no reason to install any proprietary electric drive of any description in the expectation of bettering the economics of a standard diesel drive. The motors and their electronic controllers are sophisticated and expensive. A battery bank sufficient to provide a useful motoring range is a big investment in weight, space, and money. When you add a generator and its peripherals, the cost and weight take another upward leap.

Only the simplest system will begin to pay itself off in terms of fuel not burnt, and then only if the boat sees a great deal of use. A diesel-electric system designed to closely dovetail with the way you use the boat may prove to be more efficient over time than a conventional diesel installation, but until enough systems have been installed and used and data from that use compiled and compared, we can’t know that.

So why even consider going electric? Cleanliness and silence of operation are two qualities that make electric propulsion an attractive proposition for a sailboat, but in order to enjoy them, we have to accept the limitations they impose.

A hybrid or a diesel-electric system enables us to have a single fossil-fuel power source for both propulsion and onboard appliances, but whatever fuel we might save as a consequence of motoring more efficiently for a couple of hours will be inconsequential if we run the generator all night to power the air conditioning.

Conclusions

As we go to press, pickings are slim for sailors looking for an electric solution to the diesel problem. Suppliers of components are few, prices are high, and the feedback on long-term reliability is nonexistent. On top of all this is the elephant in the room: the unexplored safety ramifications that accompany high-voltage DC.

However, none of this should deter the dedicated tinkerer who has funds to match his curiosity and who can live within the parameters imposed by electric propulsion.

Practical Sailor encourages our readers to explore the technology, because ultimately, it is the experimenters who bring us the equipment we eventually come to take for granted.

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• Electric Engines
• Success in the Real World is a Matter of Perspective

RELATED ARTICLES MORE FROM AUTHOR

I have gotten excited about repowering my Freedom 30 with an electric motor. A fellow Freedom 30 owner completed his refit about 8 months ago and is very happy with the result, although he wishes he had gone with larger Lipo batteries. He chose a motor from electricyacht.com which sells a 10KW package (quietTorque 10) including motor, performance display, throttle and shaft coupler for $6K. Batteries and charger are extra. The motor does does feature a regen capability. Figure a $10K investment. Big bucks for sure but equivalent to a yard installed diesel repower. I would do the install myself.

I am not a cruiser but have done some lengthy passages from San Francisco to Hawaii. Ideal conditions for regen. I expec between regen and a hundred watts of solar, I could have kept the bank topped up the whole way down despite AP loads, etc. The way back? Not so much. Realistically you would need a small generator and a good stock of gas if you wanted to do much motoring, Having said that, one of the boats that sailed down there with me came home with an outboard as his aux power. I think he had ten gallons of gas.

But I am not planning ocean passages in future, I will be sailing the SF Bay and coastal cruising. When I think about eliminating the engine noise, engine maintenance, fuel tank and tank maintenance, diesel hoses, diesel smell, diesel soot, diesel leaks, r=two boxes of hoses and spares. oil changes, coolant changes, transport and disposal of all the waste to the local recycling facility, lugging fuel jugs down to the boat, storing fuel, filling fuel, buying fuel, worrying about spilling fuel. I mean it just goes on and on.

Frankly, I can’t wait. In terms of range, well, I plan to get a hefty battery bank but I also intend to become a better sailor. I’ll slow down and do more sailing. Gee wiz, what a concept. I’ll be more mindful of time and tide, I’ll take advantage of favorable currents and I’ll be ready to anchor and chill when they are not favorable.

Meanwhile, Elon and his competitors are improving battery technology rapidly. Couple of years from now maybe I double range. But, by then, I won’t be worrying about it because I will be a real sailor.

I look forward to reading an update on the state of electric sailboat propulsion 13 years later…

Most of the time we leave the dock, motor for under half a nautical mile to get out of tiny Wilmette harbor and get the sails up, turn off our much abused Yanmar 3GMF, sail around, turn on the engine, lower the sails, and travel another half a nautical mile back to the dock. Almost all at a very low RPM. But, on occasion we motor or motor sail long distances for hours on end, so a battery only system would not work. But how nice it would be if we had electric propulsion for getting in and out of the harbor.

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Electric Sailboat Motor: Range, Cost, Best Kits for Conversion

Today, owning a completely green sailboat has been made possible with electric sailboat motors.

Imagine cruising with the silence of an electric sailboat motor and the ease of use with a simple press on the start button. What’s better is there are no exhaust fumes at all with significantly less maintenance.

It’s so appealing that a lot of sailing liveaboards have made their electric sailboat motor conversion.

However, some sailors are still on the fence, worrying about the range and price of the electric sailboat motor.

If you are one of them, you are in the right place!

This post will guide you through every aspect you need to know about electric sailboat motors to help you make an informed decision.

Besides, you will get professional insights on how to make the electric sailboat motor conversion for your own boat and learn the best electric sailboat motors (with honest reviews).

Table of contents:

• Electric Sailboat Motors: Confusion Explained

Electric Sailboat Motor or Combustion Motor

• Electric Yacht Motor Conversion: Two Solutions
• How to Size an Electric Sailboat Motor

Best Electric Sailboat Motors (with Reviews)

Electric Sailboat Motor: Confusion Explained

Can you go cruising with an electric sailboat motor? Can you put an electric motor on a sailboat? Are there any limitations?

Whether electric sailboat motors are a good fit for your boat is not a YES or NO question. Here we will explain your top worries with statistics and facts. That way, you can make a wise decision according to your situation.

You may hear some complaints about the batteries and range of the electric propulsion.

However, their experience may not suit electric sailboat motors.

In fact, even small electric engines work pretty well in many sailboats. That’s because most of the time, the wind can power the boat, and the motor is just used for docking or in rare times when there is no wind.

Therefore, it makes more sense to learn electric sailboat motor performance in real-world applications.

Here is a test report of a 3 HP electric sailboat motor on an RS21 racing sailboat:

As you can see, the small electric sailboat motor can run at 5.5 mph top speed for one hour continuously.

And there is a big difference in terms of range vs speed for electric sailboat motors:

If you lower the speed, the range and runtime can be greatly extended. The slower you go, the further you’ll get. For example, if you cut your speed in half, the electric sailboat motor can last 7 hours and go 20 miles within one charge.

That’s pretty sufficient if you use the electric yacht motor mostly for docking or as an auxiliary engine.

Faster top speed (and more range) is available with higher power electric sailboat motors depending on your specific requirements. Contact a specialist to design your electric sailboat motor solutions.

Also, don’t forget to get the electric sailboat motor with regeneration (See recommendations below).

That’s to say, when there is a lot of wind and you’re moving rapidly via your sails, they regenerate and store electric power on the batteries to keep you moving at other times. Solar recharging is also a plus.

Essentially, the range depends on how many batteries you have, so it’s not a limitation of electric sailboat motors but energy and batteries.

If you are still worried, you can offset this by getting a diesel generator, which is more efficient than a diesel engine. And it is a range extender when you need it, but for 90% of your motoring that you don’t need the range, you can rely on the electric sailboat motor.

Some of you might be concerned about the extra weight of the batteries.

In fact, an electric sailboat motor with lithium batteries weighs less than a diesel engine, particularly if you include the fuel weight.

If you want a lightweight electric sailboat motor solution, make sure you get one with LiFePO4 batteries . Compared with other marine batteries, they are more compact in design with much less weight and higher energy density.

Some more advanced electric motors for small sailboats (such as Spirit 1.0 Evo) feature an integrated lightweight battery. So you don’t need to worry about the complex wiring to hook it up or extra space to store the battery.

This is a huge plus if you want to use the electric sailboat motor on a tender or dinghy.

Here is also a chart that collects the weight of some popular electric sailboat motors for your reference:

For many people, another big problem with electric sailboat motors is the cost.

It’s true that a gasoline outboard with similar power is a lot cheaper to buy. However, the electric sailboat motor eventually wins in long-term operating cost. That’s especially the case if you are going to do a lot of motoring.

Electric sailboat motors save on fuel and maintenance costs, which can build up to a large amount over time.

Here is a chart that compares the cost of a 3HP electric sailboat motor (coming with a built-in battery) with its combustion counterpart:

That’s to say, you will cover the price difference for electric yacht motors eventually as long as you use it long enough. Click to check the details of the calculation .

What makes the electric sailboat motor even more worthwhile is it saves you a lot of hassles, especially for sailors who only use the engine in and out of the harbor. Dealing with the maintenance of the gas outboard for a 10 minute motor out of and into the harbor is disproportionate and painful.

*The higher horsepower electric sailboat motor may be different in terms of the cost calculation. Check out the outboard motor pricelist by HP for more information.

As you may have already noticed, electric propulsion has already been widely used in the marine industry:

It’s quiet while motoring, clean to handle, environmentally friendly, with less maintenance and operation costs.

The electric sailboat motors are easier to use with dramatically fewer moving parts to break and no worries about being a diesel mechanic to deal with the hard pulling start. You can have it always on, so it is ready whenever you need it.

And it makes even more sense in sailing applications:

You don’t really need to motor much if your plan is to actually sail. If you are completely becalmed, you will probably just need to motor at 2 knots to keep making way, which is easy for electric sailboat motors.

If you mostly use the motor to get into and out of the harbor, the electric sailboat motor also works great for you.

You can always charge up at the dock, motor out of the marina (or even motor to your sailing area or race start), then hoist the sails and when you’re through, the batteries are charged again.

The electric sailboat motor is also useful as a backup (kicker) motor in case your system goes down. That’s why you can see people pushing a lot of big boats with small electric motors. (Click to learn more information about kicker motors .)

Personally, it’s really nice to have an electric auxiliary in the boat – no smelly, messy diesel and motor oil to deal with, a much simpler system with less maintenance, and much, much quieter operation.

However, powerboats tend to have much higher requirements in terms of both power output and runtime. In that case, an electric sailboat motor can be hard to satisfy your needs.

How Do You Size an Electric Motor for a Sailboat?

As a rule of thumb, you will need approximately 1 HP per 550 lb of the displacement of your boat.

Generally speaking, a 3 HP electric sailboat motor can push a sailboat up to 25 ft and a 9.9 HP motor is sufficient for a 30 ft sailboat to motor at a satisfying speed.

However, bear in mind the horsepower you need always depends on your needs and applications.

It’s better to check the data from real-world tests to decide whether the electric sailboat motor is suitable for your specific needs.

For example, the 9.9 HP electric sailboat motor Navy 6.0 allows you to go at 6.9 mph (11.1 kph) on a 30 ft sailboat, and the range can be extended to 46.4 miles if you decrease your speed to 2.9 mph (4.6 kph).

Click to see more test reports with other electric motor and sailboat combinations, and find the electric sailboat motor that suits you best.

If you are still not sure about the size of the electric sailboat motor for you, feel free to leave us a comment and we will get back to you ASAP with professional suggestions.

Electric Sailboat Motor Conversion

Basically, there are two ways for you to convert your sailboat to a clean and quiet electric drive system:

You can either convert your current vessel to electric or buy an engineless yacht and install an electric sailboat motor on your own.

#1. Repower Your Sailboat with Electric Motor

If you decide to replace the diesel engine with an electric motor, you will need to do a lot of preparations:

The DIY approach requires an electric sailboat motor kit (including motor and controller), batteries, a good level of mechanical ability and basic electrical knowledge, as well as some common tools such as a voltmeter.

You will need to take the old engine out for the new electric sailboat motor installation. It’s not an easy task that involves removing the engine mounts and the drive shaft (dealing with the numerous hoses and cables), taking out the engine, exhaust system, fuel tank, and its attendant tubes, etc.

Remember to balance the boat to avoid listing during the electric sailboat motor conversion.

Then in with the new electric sailboat motor. The installation process can be straightforward if you choose the electric sailboat motor kit wisely (See steps below). Furthermore, you can set up solar charging for your electric sailboat motor with solar panels and charger.

Many sailors have recorded their electric sailboat motor conversion process and experience. Be sure to check them out to get some inspiration. For example, Ed Phillips has documented everything which can serve as a guide for newbies to get started.

Mind you there can be a whole heap that can go wrong in designing and maintaining the electric sailboat motor systems. You really need to be totally on top of it if you want decent performance or reliability.

If you are not that technically inclined, it’s better to talk to a specialist first to discuss your plan for a smooth electric sailboat motor conversion.

#2. Install an Electric Motor in a Sailboat

If you own an enginless sailboat, the electric sailboat motor conversion is much easier for you.

All you need to do is to find a reliable electric sailboat motor and install it in simple steps. The whole process can be easily done, even for beginners. Here we take the popular 6 HP electric sailboat motor Navy 3.0 as an example to show you the installation process:

• Step 1 : Rotate the clamps or use the screws to fix the outboard onto the sailboat.
• Step 2: Mount the steering system in the proper position.
• Step 3: Install the tiller on the electric sailboat motor.
• Step 4: Connect the batteries to the electric sailboat motor system.

Click to check the video tutorial that guides you through each step of the installation.

If you are worried about aesthetic issues and want higher horsepower options, an electric inboard motor can be a better suit for your sailboat. If you prefer an inboard motor for your sailboat, contact our OEM team to get an electric propulsion solution tailored to your needs.

Note : You might find some electric trolling motors rated by #s of thrust on the market. Actually, those electric trolling motors for sailboats can only provide limited speed and range. If you are heading into the wind, the trolling motors for sailboats are definitely not an ideal solution.

Once you’ve evaluated if electric sailboat motors are right for you, there are a lot of options for electric systems.

Here are some popular electric sailboat motors with positive reviews from customers worldwide. Fast charger is available for all the models recommended to reduce your charging stress.

#1. 3 HP Spirit 1.0 Evo

If you are looking for an electric motor for a small sailboat, be sure to check out the ePropulsion Spirit 1.0 Evo. It’s suitable for large daysailers or small cruising sailboats under 25 ft.

With the Spirit 1.0 Evo electric sailboat motor, you can go 5.5 mph (8.8 kph) at top speed on the 21 ft RS21 sailing boat, or troll for 20 hours continuously at 2.2 mph (3.5 kph) according to our test .

This electric sailboat motor with regeneration allows you to recover energy from the prop while under sail. It will start to generate power automatically when the sailing speed reaches 2 knots.

As an electric auxiliary sailboat motor, it can also be easily installed on your tender boats or yacht dinghies since it’s portable and easy to transport (with a lightweight integrated battery).

Features You Will Love:

• Come with the industry-first hydrogeneration capability
• Direct-drive technology makes it maintenance-free
• Portable with a 1276Wh large integrated lithium battery for long range
• Safety wristband keeps you safe in case of MOB
• Digital operation keeps you informed of the battery status

Spirit 1.0 Evo Electric Sailboat Motor Reviews:

“Great weekend with my 17′ sailboat powered by the Spirit Evo. This is great. Quiet and reliable. Went at 3/4 throttle for about 1.5hrs when taking it back to boat ramp.” – Robert Taylor

“Very happy with our Spirit Plus. Pushing our Kolibri 560 a 750 Kg sailboat, with ease. Doing about 5.8 km/h at 500W.” – Frank van Asten

#2. 6HP/9.9 HP Navy Evo Series

If you want a little more juice on the electric sailboat motor, check out the ePropulsion Navy Series. It offers 6 HP and 9.9 HP models for your selection and it provides sufficient power for sailboats up to 30 ft.

According to our test , the 6 HP electric motor Navy 3.0 can push the Catalina 25 sailboat (25 ft) at 6 mph (9.6 kph) top speed, while the Olga 33 sailboat (33 ft) can go at 7.5 mph (12 kph) with the 9.9 HP Navy 6.0 motor.

The Navy series electric sailboat motor also comes with regeneration features which can be recharged with hydrogeneration, wind turbine, and solar panel.

• Four controls to fit your sailboat installation and your boating style
• Accompany LiFePO4 batteries (need separate purchase) are more energy efficient
• Digital display offers real-time monitoring of the power and battery
• Magnetic kill switch and safety wristband keep you safe on the boat
• Electric start saves you trouble pulling the cord to start

Navy Series Electric Sailboat Motor Reviews:

“I have a Navy 3.0 with E80 on a Catalina 25 sailboat. It is working well. Currently I am using about 4% battery to go in/out of the marina by boat.” – Aaron Young

“Just finished my 8 weeks sailing journey in the Baltic Sea. The two Navy 3 outboards provide enough power for my 33ft catamaran. The 400W solar panels provided enough energy for engines and all other energy consumed on board with 2-6 persons. The two Navy Batteries provide power for engines and all other on-board electric devices. I never had to use shore power, so totally self-sufficient electric system.” – Martin Hildebrand

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The Promises and Pitfalls of an All-Electric Yacht

• By Tim Murphy
• Updated: November 8, 2021

This past October, I saw one of the most interesting exhibits in more than 500 new cruising sailboats I’ve reviewed over two decades. It was the Arcona 435Z, built in Sweden and introduced by Graham Balch of Green Yachts in San Francisco. Balch describes his business as “a new brokerage dedicated to the electric revolution on the water,” and it was the “Z” in the boat’s name, which stands for “zero emissions,” that made this boat so interesting. This was the first electric propulsion system—not hybrid but all-electric —I’d ever seen on a cruising sailboat.

Electric propulsion isn’t new. Since 1879, electric motors have propelled boats; a fleet of some four-dozen electric launches transported visitors around the 1893 Colombian Exposition in Chicago. But cruising sailboats are not launches, and the open sea is not a protected canal. When we’re using cruising boats as they’re meant to be used, they seldom end their day plugged into a shore-power outlet. Cruising boats comprise many devices —stove, refrigerator, freezer, windlass, winches, autopilot, radar, lights—whose power typically comes from a tank of fossil fuel. And today’s cruising sailors are accustomed to using diesel auxiliary power to motor through lulls or punch into headwinds and seas.

Starting about 15 years ago, we saw a wave of diesel-electric and hybrid propulsion systems on production and custom cruising boats ( see “Perpetuated Motion,” CW , March 2005 ). Both of those systems ultimately start with an onboard internal-combustion engine. A diesel-electric propulsion system relies on a running genset to directly power the electric motor that turns the propeller. A hybrid system relies on batteries to power the electric motor, plus an internal-combustion genset to recharge the batteries. One of the promises of a hybrid system is the ability to regenerate electrical power. Regeneration means using boatspeed under sail to turn the propeller, whose spinning shaft sends electrons from the electric motor back through an electronic controller to recharge the batteries. In such a system, the boat’s propeller is both an electrical load (when running under power) and a charging source (when sailing in regeneration mode).

The Arcona 435Z was different from both of these systems: It incorporates no onboard fossil-fuel engine at all. Instead, it has a bank of lithium batteries, several solar panels, and a proprietary propulsion leg that looks like a saildrive. “This boat,” Balch said, “has the very first production unit in the world of Oceanvolt’s newest electric propulsion system, called the ServoProp.”

For our sea trial, Balch was joined by Derek Rupe, CEO of Oceanvolt USA. “If you can sail the boat and you have some solar, you can go anywhere in the world, and you can make all your power underway while you go,” Rupe said. When we spoke in October 2020, he touted three high-profile sailors who were using the Oceanvolt electric propulsion system: Alex Thomson, for his Hugo Boss Open 60 Vendée Globe program; Jimmy Cornell, for his Elcano 500 expedition; and Riley Whitelum and Elayna Carausu, who had been teasing their new boat for months on their popular Sailing La Vagabonde YouTube channel.

The efficiency of Oceanvolt’s ServoProp and the regeneration from it is the promised game-changer in each of these boats. The ServoProp is a leg with a ­feathering propeller that can be set for optimal pitch in three modes: forward, reverse and regeneration.

“You don’t need fuel,” Rupe said. “You don’t need to dock; you can go anywhere you want to go and always have the power for living and propulsion.”

That’s the promise. But are there also pitfalls?

Innovation and Risk

Marine electric propulsion is an emerging technology. Compared with the mature and settled technology of diesel engines and lead-acid batteries, electric-propulsion systems—with their electronic controllers and lithium batteries—are in a stage of development best described as adolescent. Every sailor has his or her own tolerance for technical innovation. For the promise of fewer ­seconds per mile, grand-prix-racing sailors willingly trade a high risk of expensive damage to the sails, rig or the boat’s structure itself; cruising sailors, by contrast, tend to favor yearslong reliability in their equipment as they seek miles per day.

Folks who identify as early adopters take special joy in the first-wave discoveries of a new technology; if they’re clear-eyed about supporting an ongoing experiment, they see themselves as partners with the developers, accepting failures as opportunities for learning. Sailors motivated primarily by changing the trajectory of climate change might be especially willing to modify their behavior to limit their own output of greenhouse gases. Investing in any emerging technology asks you to start with a clear assessment of your own risk tolerance. We’ll return to this theme with one or two real-life examples.

The American Boat and Yacht Council, founded in 1954, sets recommended standards for systems installed on recreational boats. For decades, ABYC has published standards related to installations of diesel and gasoline engines, as well as electrical systems based around lead-acid batteries. By contrast, it was only three years ago that ABYC came out with its first electric-propulsion standard (revised July 2021). And only last year it published its first technical-information report on lithium batteries (a technical-information report is an early step toward a future standard). The takeaway is that if you need help servicing your diesel engine or electrical system built around lead-acid batteries, you can pull into any reasonable-size port and find competent technicians to help you. With electric propulsion and lithium batteries, that pool of skilled talent is significantly scarcer.

To say that a technology is mature simply means that we’ve learned to live with it, warts and all, but that it holds few remaining surprises. Certainly, diesel-propulsion and lead-acid-battery technologies each leave plenty of room for improvement. When a charge of fuel ignites in the combustion ­chamber of a diesel engine, some three-quarters of the energy is lost in heat and the mechanical inefficiencies of converting reciprocating motion to rotation. Lead-acid batteries become damaged if we routinely discharge more than half of their capacity. During charging, they’re slow to take the electrons we could deliver.

Lithium batteries are comparatively full of promise. Their power density is far greater than that of lead-acid batteries, meaning they’re much lighter for a given capacity. They’re capable of being deeply discharged, which means you can use far more of the bank’s capacity, not merely the first half. And they accept a charge much more quickly; compare that to several hours a day running an engine to keep the beers iced down.

But the pitfalls? Let’s start with ABYC TE-13, Lithium Ion Batteries. Some of its language is bracing. “Lithium ion batteries are unlike lead-acid batteries in two important respects,” the report says. “1) The electrolyte within most lithium ion batteries is flammable. 2) Under certain fault conditions, lithium ion batteries can enter a condition known as thermal runaway, which results in rapid internal heating. Once initiated, it is a self-perpetuating and exothermic reaction that can be difficult to halt.”

Thermal runaway? Difficult to halt? Self-perpetuating?

“Typically, the best approach is to remove heat as fast as possible, which is most effectively done by flooding the battery with water,” TE-13 continues, “although this may have serious consequences for the boat’s electrical systems, machinery, buoyancy, etc.”

If you were following the news in January 2013, you might remember the ­story of Japan Airlines Flight 008. Shortly after landing at Boston’s Logan Airport, a mechanic opened the aft ­electronic equipment bay of the Boeing 787-8 to find smoke and flames billowing from the auxiliary-power unit. The fire extinguisher he used didn’t put out the flames. Eventually Boston firefighters put out the fire with Halotron, but when removing the still-hissing batteries from the plane, one of the ­firefighters was burned through his ­professional protective gear.

Samsung Galaxy cellphones, MacBook Pro laptops, powered skateboards—in the past decade, these and other devices have been recalled after their lithium batteries burned up. In that period, several high-end custom boats were declared a total loss following failures from lithium batteries. In March 2021, a 78-foot Norwegian hybrid-powered tour boat, built in 2019 with a 790 kW capacity battery bank, experienced thermal runaway that kept firefighters on watch for several days after the crew safely abandoned the ship.

Yes, experts are learning a lot about how to mitigate the risks around lithium batteries. But we’re still on the learning curve.

ABYC’s TE-13 “System Design” section starts, “All lithium-ion battery ­systems should have a battery ­management system (BMS) installed to prevent damage to the battery and provide for battery shutoff if potentially dangerous conditions exist.” It defines a bank’s “safe operating envelope” according to such parameters as high- and low-voltage limits, charging and discharging temperature limits, and charging and ­discharging current limits.

Graham Balch takes these safety recommendations a step further: “To our knowledge, the BMS has to monitor at the cell level. With most batteries, the BMS monitors at the module level.” The difference? “Let’s say you have 24 cells inside the battery module, and three of them stop working. Well, the other 21 have to work harder to compensate for those three. And that’s where thermal events occur.”

Balch followed the story of the Norwegian tour boat this past spring. He believes that the battery installation in that case didn’t meet waterproofing standards: “The hypothesis is that due to water intrusion, there was reverse polarity in one or more of the cells, which is worse than cells simply not working. It means that they’re actively working against the other cells. But if the BMS is monitoring only at the module level, you wouldn’t know it.”

On the Green Yachts website, Graham lists five battery manufacturers whose BMS regimes monitor at the cell level. “If I were sailing on an electric boat, whether it be commercial or recreational, I would feel comfortable with having batteries from these five companies and no other,” he said.

The broader takeaway for today’s sailors is that lithium batteries bring their own sets of problems and solutions, which are different from those of conventional propulsion and power-supply technologies. A reasonably skilled sailor could be expected to change fuel filters or bleed a diesel engine if it shuts down in rough conditions. With lithium-ion batteries aboard, an operator needs to understand the causes and remedies of thermal runaway, and be ready to respond if the BMS shuts down the boat’s power.

Real-World Electric Cruising Boats

When we met Oceanvolt’s Derek Rupe a year ago, he and his wife had taken their all-electric boat to the Bahamas and back the previous season. Before that, he’d been installing electric-propulsion packages for six years on new Alerion 41s and other refit projects. “My real passion is on the technical side of things—installations, really getting that right. That’s half the picture. The technology is there, but it needs to be installed correctly.”

When talking to Rupe, I immediately encountered my first learning curve. I posed questions about the Oceanvolt system in amps and amp-hours; he responded in watts and kilowatt-hours. This was yet another example of the different mindset sailors of electric boats need to hold. Why? Because most cruising boats have just one or two electrical systems: DC and AC. The AC system might operate at 110 or 220 volts; the DC side might operate at 12 or 24 volts. On your own boat, that voltage is a given. From there we tend to think in terms of amps needed to power a load, and amp-hours of capacity in our battery banks. Going back to basics, the power formula tells us that power (watts) equals electrical potential (volts) times current (amps). If your boat’s electrical system is 12 volts and you know that your windlass is rated at 400 watts, it follows that the windlass is rated to draw 33 amps.

But an all-electric boat might comprise several systems at different voltages. A single battery bank might supply cabin lights at 12 volts DC; winches and windlasses at 24 volts DC; the propulsion motor at 48 volts DC; and an induction stove, microwave and television at 110 volts AC. A DC-to-DC power converter steps the voltage up or down, and an inverter changes DC to AC. Instead of translating through all those systems, the Oceanvolt monitor (and Derek Rupe) simply reports in watts coming in or going out of the bank.

“We keep all our thoughts in watts,” Rupe said. “Watts count in the AC induction. They count in the DC-to-DC converter. They count the solar in. They count the hydrogeneration in. And the ­power-management systems tracks it that way for shore-power in.

“On a boat like this, maybe I have 500 watts coming in the solar panels,” he continued. “So then I can think: ‘Well, my fridge is using 90 watts. My boat has an electric stove. When I cook a big meal, I can see that for every hour we cook, we lose about 10 to 12 minutes of our cruising range.’”

During his Bahamas cruising season, Rupe observed that on days that they were sailing, the combination of solar panels and hydroregeneration supplied all the power he and his wife needed. “When we weren’t sailing,” he said, “we found that we were losing 8 percent each day, in the difference from what the sun gave us to what we were using for the fridge, lights, charging our laptops, and all that stuff.”

Rupe’s solution? “Twice in Eleuthera and once outside Major’s, we went out and sailed laps for a couple of hours because the batteries were below 30 percent of capacity. It was good sailing, and the wind was coming over the shore, so we didn’t have any sea state. We did a couple of hot laps on nice beam reaches, and generated about 700 watts an hour.”

Of the three sailors Rupe touted in October 2020—Alex Thomson, Jimmy Cornell and the Sailing La Vagabonde couple—only Cornell can report back on his all-electric experiences with Oceanvolt. Alex Thomson ended his circumnavigation abruptly last November, just 20 days after the Vendée Globe start, when Hugo Boss collided with an object in the South Atlantic. And at press time in early fall 2021, Riley and Elayna had just recently announced the build of their new Rapido trimaran; keep an eye on their YouTube channel for more about their experiences with the Oceanvolt propulsion system.

As for Cornell—circumnavigator, World Cruising Routes author, creator of the transoceanic rally, and veteran of some 200,000 ocean miles—he suspended his planned Elcano 500 round-the-world expedition solely because of the Oceanvolt system in his new Outremer catamaran. His Aventura Zero Logs on the Cornell Sailing website, particularly the Electric Shock article posted on December 2, 2020, are essential reading for any sailor interested in sailing an electric boat. “Sailing around the world on an electric boat with zero emissions along the route of the first circumnavigation was such a tempting opportunity to do something meaningful and in tune with our concern for protecting the environment that my family agreed I should do it,” Cornell wrote. “What this passage has shown was that in spite of all our efforts to save energy, we were unable to regenerate sufficient electricity to cover consumption and top up the batteries.”

Cornell’s experience in that article is raw, and his tone in that moment bitterly disappointed. We recommend it as essential reading—not as a final rejection of the electric-boat concept or of Oceanvolt’s system, or even as an endorsement of Cornell’s own decision that the system didn’t work. I suspect that I may have arrived at the same conclusion. Yet given the same boat in the same conditions, one imagines that a new breed of sailor—a Graham Balch or a Derek Rupe—may have responded differently to the constraints imposed by an all-electric boat, as nearly every cruising sailor today habitually responds to the inconvenient constraints of diesel engines and lead-acid batteries.

“If you bring electric winches, electric heads and an induction stove, and then sail into a high-pressure system, you’ll set yourself up for failure,” Balch said. “You have to balance your power inputs and your power outputs.

“Sailing an electric boat is a return to the tradition of sailing that the crutch of a diesel engine has gotten us away from,” he added. “Magellan’s fleet got all the way around the world, and they didn’t have a diesel engine.”

Tim Murphy is a Cruising World editor-at-large and ­longtime Boat of the Year judge.

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This New Electric Sailing Yacht Can Charge Its Own Batteries While Cruising

The 49-footer can generate 3.5 kw of clean, green energy when sailing at speeds greater than 8 knots., rachel cormack.

Digital Editor

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It’s no easy feat to incorporate a next-gen electric propulsion system into an elegant sloop. X- Yachts appears to have pulled it off, though.

The Danish yacht maker, which has spent more than 40 years in the game, just launched a futuristic new sailing yacht that looks to be as stylish as it is sustainable. Christened the X49E , the 49-footer is the very first electric sailboat to be made by the yard.

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The 12-ton newcomer is based on the existing X49 model , but eschews the traditional diesel engines in favor of two of Oceanvolt’s 10 kW electric motors. The pods are mounted on each side of the traditional engine compartment, below the aft cabin bunks. The space which used to hold the engines now houses a 28.8 kWh lithium battery bank and an onboard DC generator with a capacity of 11 kW.

The X49E’s solar panels generate energy to power the hotel load.  X-Yachts

Range with pure electric power depends on the boat speed, wind and sea state, but X-Yachts estimates in calm conditions the yacht can travel 22.7 nautical miles at 5 knots. Of course, the diesel generator can be used to run the boat if more range is required.

X49E can also produce up to 3.5 kW when sailing at speeds greater than 8 knots. That means if you sail for roughly eight hours, the batteries will charge from empty to full. The best part is the “full tank” is 100 percent green and free of cost.

To top it off, the X49E is fitted with solar panels that will generate clean energy to power the hotel load. That is the lights, navigation systems, appliances and so on.

The first hull was built for a discerning yachtsman.  X-Yachts

”We didn’t want to be first movers on this area, but preferred to wait until technology and knowledge had matured properly”, Kraen Nielsen, CEO of X-Yachts, said in a statement . “And I’m really happy to say that the time finally is right to present the first X-Yacht with electric propulsion.”

The first hull was built for discerning yachtsman John Haurum, who has a passion for sailing both recreationally and in competition.

“My plans for the X49 are primarily to use it for long-distance cruising, but it has also been specified with performance sailing in mind and I intend to participate in challenges like Around Denmark Race and, eventually, the ARC Cross Atlantic,” Haurum adds.

Looks like you’ll see the X49E tearing it up on the ocean before too long.

Rachel Cormack is a digital editor at Robb Report. She cut her teeth writing for HuffPost, Concrete Playground, and several other online publications in Australia, before moving to New York at the…

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Volvo Penta D4 Hybrid first look: Is this the future of boat propulsion?

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Hugo Andreae gets an exclusive insight into Volvo Penta’s plans for a range of new diesel electric hybrid engines, starting with the Volvo Penta D4 Hybrid…

Volvo Penta has revealed a fascinating insight into its greener future with the launch of its first diesel electric hybrid leisure boat engine.

Although still a prototype, it is based on a standard 320hp D4 engine and DPI sterndrive with an electric motor/generator added to the driveline.

Speaking exclusively to MBY , sales project manager, Jonas Karnerfors, has confirmed that this will form the basis of a range of production Volvo Penta D4 and D6 hybrid engines.

To assess how well it works in the field, two of the prototype engines have been fitted to a 50ft aluminium fast cruiser.

Built by Marell Boats Sweden and operated by Hurtigruten Svalbard, a Norwegian-based adventure travel company, it will take visitors into the remote and environmentally sensitive waters of the Svalbard archipelago approximately halfway between Norway and the North Pole.

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The sub-zero temperatures and long running hours (it is expected to clock up 1,000 hours this year) will provide a rigorous test of the engines’ reliability, while their ability to run almost silently in electric boat mode should minimise disruption to wildlife and improve the visitor experience.

Hybrid modes

Volvo is not yet ready to share full technical details of the new hybrid engine, such as the power rating of the electric motor or size of the lithium ion battery pack, but has confirmed to MBY that the parallel hybrid system will offer three different driving modes: electric, hybrid and power.

In electric mode, it will only be capable of speeds up to around 10 knots but should be able to cruise at 5-6 knots for up to five hours, giving a range of around 30nm on battery power alone.

In hybrid mode the system itself will select whether to use the electric motor, the diesel engine or both depending on a number of different factors such as speed and battery state. In power mode both the diesel engine and electric motor will run concurrently to boost acceleration and speed.

The electric motor adds less than 500mm to the length of a D4. The battery is mounted remotely.

In fact, the electric motor actually replaces the mechanical supercharger normally fitted to the D4 and D6 engines by providing a similar torque boost to bridge the throttle lag at low RPM before the turbochargers kick in.

In the case of the Hurtigruten boat, the two 320hp hybrid engines are expected to deliver a top speed of 32 knots and a constant cruising speed of 25 knots.

Although the electric motor will be fully integrated into the driveline, adding less than 500mm to the length of the engine, the battery itself can be fitted remotely to ease packaging constraints in the engine bay.

The Marell M15 is an ideal test bed for the new technology combining lots of high and low speed running in sub-zero conditions

This can either be charged in the marina to minimise fuel burn or while the diesel engine is running. In the latter case, the system’s control unit is programmed to take advantage of the unused potential between the power that it is currently being used to propel the boat and its actual peak efficiency to recharge the batteries as efficiently as possible.

Both the driving and charging modes can be selected manually by the operator or left in fully automatic mode for the engine management system to decide.

Crucially, Volvo is determined to offer the hybrid drivetrain as an off-the-shelf package that includes the battery and propulsion unit rather than letting boat manufacturers or customers choose their battery supplier.

It hasn’t yet committed to a launch date for the production units but did indicate to MBY that it was likely to be within the next five years.

One of the big determining factors will be the size, availability and price of the battery packs. At the moment this is by far the most expensive component of the hybrid package, more than tripling the cost of a conventional Volvo Penta D4 diesel engine.

The hope is that battery density and price will come down substantially in the next few years as the drive towards electric vehicles brings reduced production costs.

Pay as you go

In the meantime Volvo is experimenting with a new form of pay-by-the-hour billing that will see Hurtigruten’s owners charged according to kW hours of engine use rather than the much higher upfront capital expenditure of buying the engines outright.

Volvo says this is an experiment in what it calls “e-mobility as a service”, and is said to be attracting a lot of interest from commercial operators.

However, it’s harder to see how the numbers would add up for leisure boat owners, who typically only run their engines for around 50-60 hours a year.

The ability to cruise in silence for up to 5 hours at a time will be ideal for wildlife watching in Svalbard. Photo: Daniel John Benton

The pilot programme is being run in partnership with Marell Boats and the Hurtigruten Group, giving Volvo a vital insight into how the new engines will integrate into the boat manufacturing process as well as how they perform in a real world environment.

Volvo is confident that the hybrid engines’ longer footprint should fit into the majority of existing boats’ engine bays but finding a suitable space for the batteries that doesn’t upset the weight distribution may prove trickier on some craft.

Volvo Penta D4 Hybrid test results

Jonas is confident that by the end of the season, the Hurtigruten test will have provided all the information needed to finalise the technical specification of the production engines.

That will just leave the question of when to make them available to the wider public and at what price they will be offered.

Either way Volvo is adamant that it is committed to launching a full range of hybrid engine solutions, not just for the D4 and D6 engines but right across its marine portfolio, including its larger IPS offerings.

“Our aim is to be the world leader in sustainable power solutions,” Jonas explains. “To do this we want to partner with companies that have the vision and courage to join us.”

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The Pros, Cons, and Future of Electric Yachts and Sailboats

• By Sail Greener
• Last updated: April 27, 2022

Sail Greener is supported by our readers. When you buy through links on our site, we may earn an affiliate commission.

If you sail you likely spend considerable time—and money—cleaning, fixing, and worrying about your diesel or gas engine. When it comes to safety, your backup propulsion is as important as your sails. Can you rely on electric motors for safety? What are the pros and cons of buying an electric sailboat?   

Diesel engines are reliable, but they pollute. Diesel (and gas) engines emit greenhouse gasses and exhaust that includes particulate matter and carcinogens that are a risk to human health. 

Until recently, alternatives to marine diesel engines were limited. Boat owners could carry out their own repower projects or purchase expensive commercial electric motors. Storage capacity was a problem.

Fortunately, the winds are shifting and there are now numerous high quality and economically competitive alternatives to traditional marine engines. In this article we describe the pros and cons of purchasing a new motor or repowering an existing engine. We also describe the market for marine electric propulsion systems and identify leading boat builders, manufacturers, and installers.

Why do we need electric sailboats?

The climate is warming and we continue to pump greenhouse gasses into the atmosphere at a torrid pace. Transport emissions, including road, rail, air and marine transportation, account for nearly a quarter of global CO 2 emissions. 1 https://www.ipcc.ch/report/ar5/wg3/transport/ According to the United Nation’s International Maritime Organization , marine traffic accounts for nearly 3% of the world's CO ­­­ 2 emissions.

While emissions from recreational boaters are less than those from shipping and fishing fleets, they are still considerable. According to an estimate from electricmotoryachts.com , if just 5% of the roughly 13 million registered boats in the United States today repowered with electric, boaters would eliminate an estimated 1 billion pounds of CO 2 emissions. Scaled across boaters around the world, the potential for boaters to meaningfully reduce greenhouse gas emissions is significant.

Exposure to diesel emissions also poses health risks. The smallest particulate matter can contribute to heart attacks, strokes, and lung disease. High exposure to small particulates can impair brain development in children. The International Agency for Research on Cancer , part of the World Health Organization (WHO), classifies diesel engine exhaust as carcinogenic to humans.   

Is there a market for marine electric propulsion?

Global concern over climate is leading to a revolution in how we produce and use renewable energy. This is particularly true in the transportation sector. Sales of electric cars in 2019 increased 40%. In 2020, Tesla motors alone produced almost 500,000 new electric vehicles. This helped to propel Elon Musk to become the world’s wealthiest person. Electric vehicle penetration is still just about 3% but growing dramatically 2 https://www.mckinsey.com/industries/automotive-and-assembly/our-insights/mckinsey-electric-vehicle-index-europe-cushions-a-global-plunge-in-ev-sales# A key factor driving this growth, according to the European Patent Office (EPO) and the International Energy Agency, is innovation in rechargeable lithium-ion batteries and other storage technology. Batteries now account for nearly 90% of all patenting activity in the area of electricity storage. Between 2005 and 2018, patenting activity in batteries and related electricity storage technologies grew four times faster than the average of all technology fields. 3 https://www.iea.org/reports/innovation-in-batteries-and-electricity-storage

It is clear we are reaching a tipping point for electric automobiles and trucks 4 https://www.theguardian.com/environment/2021/jan/22/electric-vehicles-close-to-tipping-point-of-mass-adoption . Is the marine sector also experiencing an electric revolution?

The market for marine electric propulsion systems is lagging what is happening with cars and trucks. However, the potential for growth in this sector is extraordinary. In an article published in Yachting World, Christoph Ballin, CEO of electric motor manufacturer Torqueedo, estimated that only about 1.3% of marine propulsion systems are electric. 5 https://www.yachtingworld.com/features/future-yachting-smart-technology-126136 According to an article published in 2017 by IDTechEx there are over 100 manufacturers of electric boats and ships with an estimate of more than $20 billion in global sales by 2027 for non-military boats. According to the IDTechEx report, recreational boats are the largest—and fastest—growing electric marine market by sales.

The growth potential is enormous considering the size of the recreation economy. In the United States alone, in 2019 outdoor recreation generated US$ 788 billion dollars in output. 6 https://boatingindustry.com/news/2020/11/12/orr-provides-breakdown-of-latest-recreation-economy-data/  An estimated $37 billion of this came from retail sales of boats, engines, accessories and marine services. According to the U.S. Bureau of Economic Analysis (BEA) Outdoor Recreation Satellite Account (ORSA) data, Boating and fishing was the largest conventional activity for the nation as a whole, adding  US$ 23.6 billion to the economy. This was the largest conventional activity in 30 states and the District of Columbia and the second largest activity in 11 states. 7 https://boatingindustry.com/news/2020/11/12/orr-provides-breakdown-of-latest-recreation-economy-data/

Pros and Cons of Electric Motors for Boats

What are the pros and cons of electric motors for sailing?

Pros of electric propulsion

• Less noise : Electric motors are quieter than diesel engines and nearly vibration free.
• Lower long-term cost : Motors last a long time and require no fuel. You need batteries and electricity, but the sun and wind can recharge your batteries. You won't need to constantly change engine fluids, filters, or worry about leaks or old tanks.
• Cleaner and healthier: You won't end up with an oily mess in the engine room and bilge
• No emissions, no exhaust : Passengers and crew won't be exposed to hazardous fumes and particulates. You won't be spewing out carbon pollution.
• Instant power: Electric motors can go from zero to full torque instantaneously. Motors do not need to wait for engines to warm up.
• Weight and storage : Electric propulsion systems are typically less heavy than equivalent diesel systems. OceanPlanetEnergy.com estimates that electric propulsion systems are typically 1/3 the weight of diesel systems. This depends, however, on the weight of your battery bank.
• Easier maintenance and lower costs: Electric motors are simpler and easier to maintain than diesel generators. OceanPlanetEnergy.com estimates that maintenance costs could be 1/20 of the maintenance costs of a diesel engine in the first decade, even less over time because of electric propulsion systems use far fewer moving parts.
• Increased reliability and safety : Fewer moving parts translates into fewer breakdown which means which means more safety.
• Regeneration:   Batteries can be recharged while sailing using, solar, wind, and hydro generation systems.  For example, at sailing speeds over 6 knots Oceanvolt systems are reportedly able to generate significant power for recharging the battery bank.
• Improved maneuverability: Electric motors have high torque at low RPM, which can make maneuvering in tight spaces like marinas more precise. Electric motors can switch from forward to backward instantaneously.

Cons of electric propulsion

• Range anxiety: Depending on your battery bank and ability to recharge, you may have less range with an electric motor compared to a diesel engine.
• Cost: Electric motors can be expensive relative to combustion engines, but costs are plummeting.
• Lack of familiarity : Sailors familiar with traditional engines may not feel prepared or comfortable to switch to a new form of power.
• Fires: There can be a small risk of fires from batterie with improper maintenance, but this is also true with internal combustion engines.
• Charging time: Recharging batteries can take time, but charging times are changing quickly. Tesla V3 Superchargers support peak rates of up to 250kW per car, which translates to about 75 miles of charge in 5 minutes for a Model 3 and charge at rates of up to 1,000 miles per hour 8 https://www.tesla.com/blog/introducing-v3-supercharging . In January 2021 the Israeli company StoreDot announced new “exreme-fast-charging” lithium-ion batteries that could charge a car battery capable of 100 miles of charge in 5 minutes.   It will only be a matter of time before similar speed and capacity is available for boaters.

Industry Leaders

Who are industry leaders in the electric sailboat space?

Electric propulsion companies

Numerous companies produce electric and hybrid propulsion systems for the marine sector. Some of the best known and highest quality brands that provide electric propulsion systems for yachts and sailboats include:

• Elco Motor : Elco is one of the industry leaders in this field. The company has been around for more than 125 years and now produces a wide range of outboard and inboard electric and hybrid propulsion systems. 
• OceanVolt : The Finnish company is one of the industry leaders in electric propulsion. The company produces a wide range of electric propulsion systems for monohulls and multihulls. The company has provided cutting-edge electric propulsion systems for Vendée Globe racers, including Alex Thompson’s Hugo Boss and Conrad Colman in 2017, and other racers like French Olympic sailor Damien Seguin.
• Torqeedo : When Torqeedo was founded in 2004, concepts like “clean tech” and “electromobility” were just a glimmer in Mother Earth’s eye.  One of the pioneers in the modern marine electric propulsion sector, Torqeedo is now one of the market leaders. The company offers outboard and inboard electric motors and hybrid drive systems ranging from 0.5 km to 100 kw in addition to diverse accessories from lithium batteries and solar charging equipment to smartphone apps.
• Aquamot : This German company produces in-house electric propulsion systems for electric for boats and ships, including motors, batteries, and chargers.
• Kraeutler Elektromotoren produces a wide range of industrial, ship drive, and boat motors, including drive units for motor and sailing boats.

Electric sailboat manufacturers

Who builds sailboats with electric motors?

Electric propulsion is going mainstream. Dozens of boat builders are building electric-only boats (like SoelYachts.com and Silent-Yachts.com ). Some traditional yacht builders now offer electric propulsion options—and this will likely grow to include all major manufacturers in coming years. Examples of leading yacht manufacturers that include electric propulsion options include:   

• Arcona Yachts : A leading builder of high quality yachts from Sweden, Arcona is starting to offer high quality zero-emission models, such as the Arcona 415 .
• Alva Yachts : The German luxury electric yacht brand has designed both mult-hull (non-sail) and monohul (sail) boats. The company’s 25-m Ocean Sail 82 was designed with a hybrid propulsion system and a high capacity battery bank.
• Baltic Yachts : The Finish producer of luxury yachts and a world leaders in advanced composite yacht building in 2020 selected Oceanvolt for the company’s 68-foot Café Racer manufactured in Finland. The Javier Jaudenes designed boat is just over 20 meters long and 5.5 meters wide. 
• In 2001 Elan Yachts and Oceanvolt agreed to partner to build a full range of electric-powered yachts ranging from the luxurious GT6 to the the sporty E-Line performance cruisers.
• Hanse Yachts : The world’s third largest boat builder, Hanse produces the Hanse 315, which includes an electric rudder-drive option.
• Salona Yachts : A Croatian boatbuilder, Salona builds the Salona 46, a fast, comfortable, and luxurious electric yacht and winner of the Best Green Boat Award at the  Newport International Boat Show . 
• Sunreef Yachts Eco :   A manufacturer of luxury bespoke multihulls, Sunreef Yachts Eco catamarans are equipped with composite-integrated solar panel systems and lightweight batteries for energy efficiency and environmentally-conscious luxury cruising.
• Wally : The Dutch yacht builder produces, among its many other models, the 11.35 meter Wallynano MKII, which relies on an OceanVolt electric propulsion system
• Zen Yachts : A new company established in 2021, Zen builds what it claims is the world's first series production catamaran equipped with a wingsail.

Electric conversion companies

Who can help me convert my sailboat to electric propulsion?

A growing number of companies are dedicated to helping boat builders and individuals convert their yachts. These companies may provide design and support options for advanced battery systems, solar and wind systems, hydrogenation, and overall system design. Some of these companies produce their own electric motors and systems. Leading companies in the field include:

• OceanPlanet Energy : This company includes some of the giants of the industry. Bruce Schwab was the first American to officially finish the Vendee Globe. Nigel Calder is one of the best known sailing technology writers, including his must-read classic, Boatowner’s Mechanical and Electrical Manual. The company provides energy storage, charging, and monitoring systems; system design and consulting.
• Electric Yacht : The Minnesota, USA-based company with the eponymous name supports sailors interested in electric propulsion systems. The company helps boaters design and size system and provides motor kits, batteries, chargers, and other components. The company provides examples of conversion projects on its website.
• e Marine Systems specializes in distributing solar panels, wind generators, electric propulsion drives, inverters, and energy storage systems. The company is located in Fort Lauderdale, Florida, USA.
• Naval DC produces both “pure” solar and hybrid electric systems ranging from 10 kW to 1 MW. The company provides lithium battery solutions, data and monitoring systems, electric propulsion, and matched propeller systems.

Yacht dealers

A small but growing number of yacht dealers offer new and used electric boats. Green Yacht Sales is an example of a small company that supports the sale of electric yachts and systems from diverse manufacturers.

Global clearinghouses, like YachtWorld and Boat Trader , now provide options to filter searches for electric propulsion sailboats.

Battery technology and companies

Until recently, the amount of energy batteries could store was limited. The cost of buying a new battery bank was prohibitive for most sailors. Today, however, costs are dropping and batteries provide more charge. Range anxiety remains one of the biggest reasons sailors don’t want to swap out polluting diesel engines for quieter and cleaner all-electric systems. However, this concern will soon be obsolete.

There are many high quality marine battery suppliers. Some of the major players in the LiPO market include:

• ChargeEx Lithium Ion Batteries
• Dakota Lithium
• Dragonfly Energy
• Victron Energy

Successful Examples

Okay, this all sounds good in theory, but is it really possible to throw out your old engine and install a new motor? Here are a few examples of individuals and companies making the switch to electric yachts.

As with many disruptive technologies, it is easier for wealthy individuals to pay more—often much more—for tomorrow’s technology today. That said, these Super Early Adopters are a harbinger of things to come. These individuals may be risk takers but they are also typically really smart and forward-thinking.

Swedish billionaire Niklas Zennstrom is one example of a pioneering “mogul” in the electric yacht world. The founder of Skype and former Time Magazine 100 Most Influential People awardee, in 2018 Zennstrom’s team launched Rán VII. Yachtingworld described the boat as “…so angular it calls to mind Darth Vader or a Stealth bomber.”

Zennstrom shared his views on the future of electric racing in a CNN article in 2018:

“Having gone through the design, build and initial test cycle there is no doubt to me that the future for racing yachts is electric propulsion. It's lighter, less drag, quieter, and most importantly it is environmentally friendly.”

Do-it-yourselfers have been converting electric sailboats for years. The mainstream boating magazines and the media are increasingly showcasing the stories of these sailors retrofitting their boats. A few examples of well-publicized electric yacht conversion stories include:

• In 2019 Yachting World wrote an article, “How hybrid sailing yachts finally became a feasible option.”
• Dufour 382: According to an article in Yachting World , the owners Alcyone , a Dufour built in 2016, was retrofitted with an Oceanvolt SD15 saildrive moto r.

The future of electric sailboats

We are facing a climate emergency and the world is mobilizing to reduce emissions of greenhouse gasses. A growing number of boat builders, engine and battery producers, service companies, and individuals are addressing this need by building and retrofitting emission-free sailboats.  We are still in the early stages of this transformation, but change is coming quickly.

Some of the major challenges—and opportunities—for catalyzing this transition in coming years include:

• Battery storage, charging, and cost: The pace of technology change in the battery sector is dizzying. The amount of charge, the time to charge, and the price per kilowatt of battery storage systems are all improving.  Superchargers are already widespread on land. How long will it take for marine supercharging stations to fill the world’s marinas?
• Overcoming tradition : Sailors who have used the same technology for decades may hesitate to switch to new technology. Sailors used to heavy yachts and small batteries may look with skepticism on this new technology. Range anxiety is very real in the middle of the ocean. 
• Cost : As with any new technology, early adopters may have to pay more. The cost of electric propulsion, solar and wind power, and battery storage are dropping quickly. Cost will soon be less of a concern and may become a clear benefit.
• Retrofits: Many boats still sailing form 1960s and 1970s so 50 years of old boats locked in. But this is also an opportunity for individuals and companies who are willing and able to take this space
• Manufacturing: making boats expensive and companies may not want to take risks. But new companies are emerging, and the major yacht companies now coming out with electric options (examples).

We are at the dawn of a new age of sailing. With each passing month electric propulsion technology is improving. Motors are getting better, batteries and solar panels are getting cheaper, and electric sailboats are starting to become mainstream.

Finding more information

If you want to learn more about healthy products, check out The Sail Greener Guide to Healthy Sailing . If you want to learn more about who is working to conserve the ocean, see our list of The Best Ocean Conservation Organizations for Sailors .

• Sail Greener
• Originally Published: February 26, 2022

Table of Contents

• climate , diesel engine , electric motor , environment , sailboat , yacht

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Yachting World

• Digital Edition

‘Electric yacht propulsion opens doors to a completely different way of thinking about sailing’

• Rupert Holmes
• April 23, 2024

Sailing with electric propulsion is very different to doing so with a diesel engine and may cause you to reconsider your diesel usage. Rupert Holmes reports

Electric propulsion is rapidly becoming established in the mainstream yacht market. This is increasingly driven by customer demand, often by people who own electric or plug-in hybrid cars and are more than happy with the balance between their advantages and shortcomings.

In my role testing new yachts I’ve sailed an increasing number of boats with electric and hybrid propulsion over the past six years, ranging from lightweight daysailers through smaller cruising yachts to heavy aluminium bluewater cruisers and large cruising catamarans .

I quickly discovered that electric yacht propulsion opens doors to completely different ways of thinking to the diesel engines we’re accustomed to using, especially when motor sailing.

Throttling back

Many diesel powered yachts carry enough fuel for the rate of consumption to never be a worry. However, the further you voyage the greater the chances you’ll opt to throttle back to extend range. It’s incredibly easy to underestimate the dramatic effect this has on energy use, whatever type of fuel is used.

The wave making resistance of a hull increases exponentially at speeds above 1x the square root of the effective waterline length in feet. It therefore takes three times more energy to push a boat with a 36ft (10.9m) waterline at 8 knots than at 6 knots.

Accurate monitoring of electric systems.

Additional efficiencies can be gained by throttling back further. As with air resistance when driving on a motorway, frictional resistance of the water on the hull varies with the square of boat speed. Reducing the speed of a 36-footer from 6 knots to 5 reduces total energy consumed by roughly a further 30%. At 5 knots it therefore requires less than a quarter of the energy needed to push it at hull speed of 8 knots.

This helps explain why many boats with electric propulsion appear to have relatively small battery banks. The same is also true of a Tesla – a Model S with 500kW of propulsion power may have an 80kW battery, yet the car doesn’t run out of power after less than 15 minutes – its range is over 300 miles.

As with a boat, most of the time only a small proportion of the potential power is being used. With a Tesla it’s on tap to provide supercar levels of acceleration for less than five seconds, while on a boat it’s there for manoeuvring and for punching head seas for short periods, such as leaving harbour or rounding choppy headlands in strong wind over tide conditions.

Article continues below…

Modern reaching and downwind sails have revolutionised the sail area it’s feasible for a lightly crewed cruising yacht to carry in light airs. When using a dedicated reaching sail, such as a Code 0, many yachts can now sail at close to the true wind speed in breezes of 4-8 knots. These sails are just as relevant to older cruising yachts and heavy displacement new designs as to very light, high performance craft.

This ability to maintain speed under sail reduces the amount of time spent under power while on passage and therefore effectively increases range, whether you’re using diesel or electric propulsion. In the case of the latter, most electric propulsion systems also have a regeneration function, capable of putting significant amounts of power back into the battery bank while under sail.

Well managed solar and hydrogeneration power on the electric Windelo Adventure 50. Photo: Andreas Lindlahr/EYOTY

The power these produce also increases exponentially as boat speed rises. In lighter airs this can make gybing wide angles to increase apparent wind when sailing downwind an important strategy. If doing so increases boat speed from 5 to 7 knots, for instance, the rate of charge doubles, which helps explain why some all-electric yachts can work as long-distance cruisers.

Depending on the boat, in less than 10 knots of true wind optimal downwind VMG is likely to be found at true wind angles of around 135°-140°. This means you’re sailing 30% further, but expecting the increase in speed to be larger than that figure.

Motor sailing with electric power is very different to doing so with a diesel engine. Unlike a diesel, electric motors can be used to give just a small extra push that helps increase apparent wind in a virtuous circle. When I tested a hybrid Ovni 430, for instance, reaching in less than 4 knots of true wind with mainsail and Code 0 just 3.3kW of push from the electric motor – less than 14% of its rated output – was enough to double boat speed from 2.2 to 4.5 knots. By contrast, 11kW is needed for the boat to maintain a 6.8 knot cruising speed under power alone.

The onboard power system of a Windelo Adventure 50. Photo: Andreas Lindlahr/EYOTY

Nevertheless, making good progress towards a downwind destination can be notoriously difficult so a big asymmetric spinnaker designed for downwind VMG angles is a huge advantage. Unlike a race sail this doesn’t need to be made of super light material – regular 0.75oz, or even a more robust 0.9oz cloth, works well.

Even then it’s not impossible to imagine a scenario in which an all electric long-distance cruising yacht without a back-up generator might reach back and forth with the Code 0 in very light airs just to generate enough electricity to keep the freezer cold.

But that may not be as much of an absurd idea as it initially sounds. When racing offshore we often use a similar strategy in a near calm, having first identified where the next new (stronger) breeze will be found. Instead of aiming solely to reduce the distance sailed, this is usually a faster way to get downwind in very light airs than pointing directly at the next waypoint and is a strategy cruisers can also employ to good effect.

Into the wind

The other situation in which motor sailing is common is to improve progress when close-hauled. In light airs a small push using electric propulsion can again be used to boost speed without a big power drain. However, the situation is very different when punching a big head sea in strong winds, when a considerable amount of power may be needed.

Clean and compact electric propulsion unit in an X-Yachts Xc 47. Photo: Ludovic Fruchaud/imacis.fr

This is arguably a weakness of electric propulsion, other than in yachts with large range-extending generators. It’s a much smaller problem for designs that sail efficiently to windward and have quality sails that maintain their shape even in gusts than for those that tack through big angles and have badly stretched Dacron sails.

The extent to which getting in and out of harbour and manoeuvring in port typically depletes the battery of course varies in different places. There’s a big difference between a marina berth a few hundred metres from open water and those that are a long slog up miles of tidal estuary.

Last autumn I checked out two yachts weighing 8.8 and 15 tonnes respectively in this respect: the Bestevaer 36 in La Rochelle and an Xc 47 at Port Ginesta near Barcelona. With the former we had no need to use more than 2kW of the 11kW of available power at any time while entering port and manoeuvring, while average consumption was closer to 500W. This reflected time manoeuvring at slow speed in a confined space, handing sails and preparing fenders and lines.

Manoeuvring the Xc 47 in harbour, holding station against a 15-knot headwind while we sorted lines and fenders, used only 300-500W of propulsion power, despite the boat’s high topsides and we could have done that for 100 hours before depleting the battery bank.

Motor sailing can be an efficient use of electrical power. Photo: Ludovic Fruchaud/imacis.fr

Is electric propulsion always greener?

There’s no one-size-fits-all strategy for the most sustainable solution for a yacht’s auxiliary propulsion. The extra carbon emissions associated with manufacturing an electric car is often offset within 15,000 miles thanks to their impressive efficiency compared to internal combustion engine vehicles.

However a recent well publicised ICOMIA report found privately owned sailing yachts clock up an average of only 24 engine hours annually, so the carbon footprint associated with producing the battery pack is never recovered.

The recommendation to minimise life cycle carbon emissions is therefore to use a second generation biofuel such as HVO, which is typically produced from biowaste material. These are very different to first generation biofuels, which were very hygroscopic and provided a fertile breeding ground for microorganisms that were prone to blocking fuel filters.

The equation is massively different for charter yachts and owners who spend considerable periods of time on board. An independent study commissioned by Fountaine-Pajot showed that 80% of the yard’s carbon emissions stem not from manufacturing processes, but from the use of its yachts during only the first 20 years of their life.

In this situation electric or hybrid propulsion is likely to make a very sustainable proposition.

Nevertheless, just as environmental considerations aren’t always a factor for owners of enormously powerful electric cars with 0-60mph acceleration times well under four seconds, a growing number of yacht buyers are opting for electric propulsion for reasons other than its apparent green credentials.

Benefits include quiet, odour-free running, space savings, reduced maintenance, the ability to recharge batteries – effectively refuelling while sailing using only the wind – and a huge amount of torque at low speeds that can make difficult manoeuvres in tight spaces a lot less daunting.

Key rules for sailing an electric boat

• Don’t try to motor or motor sail too fast – trying to get close to hull speed takes an enormous amount of energy.
• Good reaching and downwind sails help minimise the time spent under power, while maximising opportunities for regeneration while under way.
• Don’t try to sail dead downwind in light airs – when true wind is under 10 knots a true wind angle around 135°-140° invariably gives better results.
• Use the on-screen data to optimise boat speed and power consumption. Often only a very small push from the motor will result in a useful speed gain when motor sailing.

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Diesel Electric Drive

• By Chuck Husick
• Updated: October 4, 2007

Siemens EcoProp

Your next yacht may be powered with a new, but at the same time old and extensively proven, power system-a diesel electric drive. First used in 1903 to propel the triple-screw Russian tanker Vandal on the Volga River and Caspian Sea, diesel electric propulsion is now used in the most modern cruise ships and in thousands of other commercial vessels. Although the idea of powering your yacht with the indirect, two-step diesel electric energy transfer system may appear to be unnecessarily complex, its many advantages can make it a compellingly attractive alternative to a conventional direct mechanical prop-shaft drive.

The benefits of diesel electric drive begin with the design freedom the system affords the yacht’s designer. The engine can be installed wherever appropriate to achieve optimum use of space for the accommodation. Noise and vibration are more easily suppressed than in a conventional direct engine-to-propeller drive. Turning the props with electric motors enhances slow-speed maneuverability by providing unrestricted minimum prop speeds with 100 percent torque available to provide immediate power response at all times. Prop synchronization is automatic and extremely precise. When under way all of the electrical power required by the vessel can be supplied from the diesel electric propulsion system, eliminating the need to run a genset. A diesel electric power system can drive multiple propellers from a single engine or use multiple engines to power one or more props. In a twin-engine/twin-prop system, one engine can power both props when operating within the speed limits imposed in many areas. Electrical power from the vessel’s genset can be used to propel the boat, providing a built-in backup-especially valuable for yachts with single-engine installations. Conversely, the propulsion system can serve as a backup for the yacht’s gensets.

The more than 100-year history of marine diesel electric systems began as a response to the impossibility of quickly reversing the direction of rotation of early direct-to-prop-shaft-coupled diesel engines. With a diesel-powered direct current (DC) generator and a DC motor connected to the prop shaft, the direction of prop rotation could be controlled by a switch. The 100 percent torque, zero-speed capability of the electric motor led to the overwhelming use of diesel electric power for railroad locomotives. Diesel electric drives found a natural application in submarines and many surface ships. Today’s cruise ships, where 70-80 percent of the total onboard power is required for the “hotel” side of the vessel, are diesel electric powered. The power demands can be enormous at times. A trivial example: 1,500,000 watts, equal to more than 1,400 hp, is needed to simultaneously power half of the 1,500-watt hair dryers on a 1,400-stateroom cruise ship.

While the equipment designed to serve the massive needs of cruise ships is unsuitable for any reasonable-sized yacht, numerous land-mobile applications including buses, very large trucks and the cranes used in container ports need power levels similar to those required by a yacht. These land-mobile applications require high overall efficiency, installation flexibility, virtually 100 percent torque at close to zero speed and must meet demanding reliability and durability standards. Fortunately, equipment designed and perfected for these uses is ideal for propelling many types of yachts.

From the helmsman’s standpoint the Siemens diesel electric propulsion system is totally transparent, functioning identically to a conventional power control system, with some welcome and useful advantages. In a twin-prop installation, two conventional-appearing single-lever electronic power controls send commands to the drive control system computer (DICO in Siemens’ terms). Digital messages from the DICO manage the diesel engine’s speed governor and control the current flow from the propulsion converters to the prop-drive motors. The power curve of the engine is programmed into the control computer and used to set engine rpm to the speed that provides the required power with optimum fuel efficiency. It is generally unnecessary for the helmsman to monitor engine rpm. Placing a prop control in neutral allows the prop to freewheel, with no risk of damaging the gearbox, a benefit when the vessel is propelled by the other prop. There are no restrictions on rapid movement of the control from ahead to astern. Moving both controls beyond a preselected prop shaft speed, usually about 400 rpm, will automatically and very precisely synchronize the propellers. In fact, the precision with which the system “knows” the relative rotational position of each prop shaft appears to be sufficient to allow future addition of a prop-phase relationship control. Vibration and noise can be minimized with careful control of the relative position of the blades on one prop with those on the other prop. This technique is common on many multiengine aircraft and is called prop phasing.

In a diesel electric system, the engine can be mounted virtually anywhere in the hull and in whatever orientation is required to achieve optimum use of space. With no need to provide a mechanical power-transfer connection to the hull, the engine mounts can be chosen for optimum vibration isolation. If desired, the engine can be totally enclosed in a sound shield, providing superior sound attenuation without the need to insulate an entire compartment. The incorporation of thrust bearings on the prop shafts ensures precise alignment with the “P” bracket and the prop-drive gearbox, reducing wear on the cutlass bearing and shaft noise. The small size of the prop-drive motor and gearbox also makes it possible to locate the props at the most advantageous position on the hull-a great advantage.

A typical Siemens single-engine twin-prop diesel electric propulsion system is comprised of a permanent magnet three-phase alternator powered by the diesel engine through a speed-increasing gearbox, two short-circuit-proof solid state power inverter modules, two 3-phase permanent magnet prop-drive motors, associated prop-drive gearboxes, a control computer and a conventional-appearing helm control station. System components are surprisingly compact and lightweight. The 145 kW (194 hp) alternator suitable to power a 48-foot trawler yacht is 10 inches square, 22 inches long and weighs 264 pounds. Each of the 114 hp drive motors is similar in size and weight. The 40 x 23 x 7 inch inverter modules are typically bulkhead mounted. The spiral bevel gearboxes used to connect the alternator to the driving engine and the drive motors to the propellers are 98 percent efficient and have a medium duty life expectancy of 25,000 hours. Gearbox power capacities range from 150 to 600 hp, meaning that they can be coupled to multiple alternators or motors to meet the power requirements of larger vessels. All of the system’s power-handling components, alternators, motors, gearboxes and power inverters are cooled with a circulating flow of water/glycol. The system is also continuously monitored, by using temperature sensors built into the alternators, motors, gearboxes and inverters.

Operating efficiency is an important part of the evaluation of any power delivery system. Although the alternators, inverters, motors and gearboxes used in the Siemens system operate efficiently, the total energy loss through the system will typically exceed the losses imposed by a conventional marine gear-coupled drive. However, the efficiency loss is to a large degree offset by the ability of the electronic control to precisely match the engine’s power curve to the vessel’s propellers. In a conventional direct mechanical prop-drive system, the fixed pitch propeller can be matched to the engine and the hull at only one point, maximum engine rpm. At all other engine speeds the engine turns faster than is necessary to produce the required power. The diesel electric drive matches the prop load to the engine, producing a result similar to that achieved with use of a controllable pitch prop. Using one large engine to power two propellers can provide an efficiency advantage compared with use of two engines providing the same total power. Depending on the positioning of the engine, power loss due to exhaust backpressure may be less than what can be achieved in a conventional installation. The option of drawing the vessel’s AC house power from the propulsion system when under way, eliminating the need to run the vessel’s genset, can improve fuel efficiency. Overall, the fuel economy of the diesel electric drive will be close to or as good as what can be achieved using a direct-drive system.

In many installations the cost of a single-engine twin-prop diesel electric power system will be no more than a conventional twin-engine direct-mechanical drive installation. Properly integrated into the design of the vessel, the diesel electric drive’s many attributes will likely make it the preferred propulsion system for a growing number of yachtsmen.

Contact: www.sea.siemens.com/marine/ .

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Diesel Electric Propulsion: Is This A Safer, More Efficient Solution For Your Vessel?

• June 18, 2017
• Quite Interesting

Although the idea of powering your vessel with the indirect, two-step diesel electric energy transfer system may appear to be unnecessarily complex, its many advantages can make it a compellingly attractive alternative to a conventional direct mechanical prop-shaft drive. When under way all of the electrical power required by the vessel can be supplied from the diesel electric propulsion system, eliminating the need to run a genset.

A diesel electric power system can drive multiple propellers from a single engine or use multiple engines to power one or more propeller. In a twin-engine/twin-prop system, one engine can power both props when operating within the speed limits imposed in many areas. Electrical power from the vessel’s genset can be used to propel the boat, providing a built-in backup-especially valuable for vessels with single-engine installations.

Conversely, the propulsion system can serve as a backup for the gensets. The use of electric propulsion in certain vessel types is well-known. In marine applications, nearly all the energy is produced by diesel engines. Using an electric propulsion system, where the energy transmission is electrical and the propulsion and thruster are variable speed electrically driven, fuel consumption can be reduced significantly for many vessel types with environmental benefits.

Diesel Electric Systems have been in use to propel vessels for more than 100 years. Branobel launched the first diesel-electric ship in 1903, and since that day, diesel electric propulsion systems have evolved and today they can be found in all boat sizes and applications. But how do you know when to utilize diesel electric technology for your vessel? The investment in Diesel Electric vessels have doubled in the past 4 years, while the construction of purely mechanically propelled vessels have slowed down. But what are the reasons for this growth? Some of the benefits of the Diesel Electric systems are:

Effective design: The ability to locate your generators in any part of the vessel independent of where the power will be used;

Smaller Engine Rooms: Possibility to replace a big slow speed engine with multiple smaller generators;

Reduced Noise and Vibration: No need for long drivelines;

Flexibility: Capability to share the power of one unit with multiple devices (main propeller, bow thrusters, hotel load, pumps, etc);

Redundancy: Generators can be reassigned to cover any machine downtime;

Efficiency: Depending on the application the system can provide better fuel efficiency (mainly if there are requirements for long periods of low speed/load)

Fuel consumption savings calculation: The optimum operation point of a diesel engine will typically be around a load of 85 percent of the Max continuous rating (MCR). Moreover, the efficiency level drops quickly as the load becomes lower than 50 percent of MCR. With the help of the electric system, the mechanical propulsion prime mover is replaced by diesel-electric prime movers that will automatically start and stop as load demand varies. In comparison to a conventional vessel with mechanical propulsion, this enhances the efficiency of the energy usage and reduces the fuel consumption by keeping the average loading of each running diesel engine close to its optimum load point.

However, in some vessel applications, the load variations can be large and rapid. It is impossible to make the generators switch on and off every five seconds as would be the case with DP vessels. By using super-capacitors to supply the load variations, and hence let the diesel engines provide the average load, the peak power of the power plant will be reduced, allowing the average loading of the engines to increase to a more optimal point with lower specific fuel oil consumption. The savings in fuel consumption will depend on many parameters such as actual variations in the load, the average load and the number of prime movers.

In many installations the cost of a single-engine twin-prop diesel electric power system will be no more than a conventional twin-engine direct-mechanical drive installation. Properly integrated into the design of the vessel, the diesel electric drive’s many attributes will likely make it the preferred propulsion system for vessel owners and operators now and in the future.

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OXE HYBRID 450

Introducing the OXE Hybrid 450, the world’s first diesel-electric hybrid outboard. Technology, available today, to transition demanding users into the future.

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• OXE Hybrid 450

DIESEL-ELECTRIC HYBRID OUTBOARD

OXE Marine has a vision that drives everything we do; we want to make life at sea prosperous for people and planet. We are redefining the evolution of the diesel outboard, and are proud to unveil our latest outboard concept, the OXE Hybrid Outboard.

Sign up for our waiting list now.

450 horsepower of pure power. The (r)evolution continues. Our latest concept is a marriage of clean electric power and our robust and efficient OXE300.

The electric motor is strategically located under the cowling, connected to the drive-belt for seamless operation. Not only does this enhance performance, but it also allows the motor to serve as an alternator, providing the ability to charge the batteries while running in diesel mode. This advanced technology sets the OXE Hybrid 450 apart from the competition, offering a superior boating experience.

Harness the power of both worlds

Efficient and clean electricity meets robust and powerful diesel, in a merge previously unheard of in an outboard.

Discover the OXE Hybrid 450 , a new concept model based on OXE Marine's leading diesel outboard technology combined with an electric motor, utilizing readily available technology, presenting unbeatable speed and torque. The OXE Hybrid 450 offers all the benefits of an OXE Diesel outboard along with a fully electric propulsion system – providing full electric drive, increased fuel savings and additional range and power when needed.

Target Specifications 1

Electric Motor

Electric architecture: Axial Flux Motor

Electric motor: 150 hp, 400 volt, 124 Kw, 230Nm

Battery: Configuration Application Dependent

Technical Specifications

Diesel Engine

Engine type: Diesel Engine, L6. Block built by BMW.

Displacement: 3.0 L

Intake: Turbocharged, intercooled.

Torque: 680Nm at 1750 rpm

Power: 300 hp at 4200-4400 rpm

Fuel: Diesel EN 590, ASTM D 975 No.1 No.2. JIS KK2204, F54 & F75, biofuels HVO100 and B7

A concept in development

OXE Marine are developing the next outboard for demanding users. Still in a concept phase , the first prototype of the OXE Hybrid 450 was revealed at Miami Boat Show in 2023. More information on public release to come. 

1. Targeted figures. Subject to change. 

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Diesel Outboard News

Classic look hydrofoiling electric boat debuts in Moscow

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VESSEL REVIEW | Sinichka – Electric commuter boats designed for Russia’s Moskva River

A series of three new electric monohull commuter ferries have already begun operational sailings on the Moskva River in the Russian capital Moscow.

Built by Russian shipyard Emperium, sister vessels Sinichka , Filka , and Presnya – all named after rivers in Moscow – are being operated by the Moscow Department of Transport and Road Infrastructure Development (Moscow Deptrans). They are the first units of a planned fleet of 20 vessels that will serve the capital city and other nearby communities. The new ferry system will be the water transport system to be operated on the Moskva River in 16 years.

Each vessel has a welded aluminium hull, an LOA of 21 metres, a beam of 6.2 metres, a draught of only 1.4 metres, a displacement of 40 tonnes, and capacity for 80 passengers plus two crewmembers. Seating is available for 42 passengers on each ferry, and the main cabins are also fitted with USB charging ports, wifi connectivity, tables, toilets, and space for bicycles and scooters. The cabin layout can be rearranged to allow the operator to adjust the distances between the seats and to install armrests of varying widths.

An open upper deck is also accessible to passengers and is the only area on each ferry where smoking is allowed.

The ferries are all of modular construction with each ferry's wheelhouse, main cabin, and other structural elements being built as complete, separate components. This enables the ferries to be easily dismantled for transport to anywhere in Russia by rail and then quickly re-assembled within seven days.

The ferries are also ice-capable. Recently completed operational trials on the Moskva showed that the vessels can also easily navigate under mild winter conditions with broken surface ice, though year-round operations are planned for the entire fleet.

The ferries are each fitted with 500kWh lithium iron phosphate battery packs that supply power to two 134kW motors. This configuration can deliver a maximum speed of 11.8 knots, a cruising speed of just under 10 knots, and a range of 150 kilometres.

Emperium said the transfer of rotation of electric motors to the propeller is carried out by direct drive. As a propulsion installation, a pulling rotary propeller-steering column with double screws is used. The installation of double pulling screws, with similar power, allows an operator to increase the efficiency of the propulsion system to deliver a slightly higher speed or to reduce energy consumption. This arrangement also provides the ferries with enhanced manoeuvrability necessary for navigating in close quarters.

The batteries themselves have projected service lives of 10 to 12 years and are fitted with safety features such as built-in fire extinguishers and gas vents. Quick-disconnect features allow the batteries to be easily removed for replacement or maintenance.

Some of our readers have expressed disquiet at our publication of reviews and articles describing new vessels from Russia. We at Baird Maritime can understand and sympathise with those views. However, despite the behaviour of the country's leaders, we believe that the maritime world needs to learn of the latest developments in vessel design and construction there.

Click here to read other news stories, features, opinion articles, and vessel reviews as part of this month's Passenger Vessel Week.

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