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steel hull catamaran



From its chiseled profile and imposing stance to the amazing combination of speed and range afforded by its high-efficiency catamaran hull design, M48 defies convention at every turn and is like nothing else on the water.

This 48-meter, three-decked, all aluminum catamaran is a rugged and capable purpose-built oceangoing craft enabling global exploration and delivering self-sustaining independence for months on end.

Among the many advantages of Metal Shark’s high-efficiency Incat Crowther catamaran hull design, M48 delivers nearly twice the range of a comparably sized traditional monohull yacht. At a long-range speed of 10 knots, M48 boasts an unbelievable 11,000 nautical mile range. At a 17-knot cruise speed, M48 delivers an impressive 4,500 nautical mile range, and still offers a range of over 2,500 nautical miles at a 23-knot sprint speed, all while offering unparalleled ride, shallow draft capability, and increased stability while at rest.

M48’s unique combination of speed and range opens up myriad opportunities for exploration and adventure on the fly, without need for an elaborately planned itinerary. Travel from New York to Miami in under 48 hours. Cross oceans with ample fuel to accommodate any change of plans. And, wherever your destination may be, you’ll enjoy unmatched independence as M48 becomes its own self-sustaining island, with robust off-grid capabilities that allow you to drop anchor in any harbor and stay for as long as you like.

M48 boasts a sleek and modern elevated interior that imparts the feel of a high-end city apartment. A panoramic window treatment and tasteful, refined interior finishes put the emphasis on the journey, enveloping occupants in spacious, uncluttered surroundings while affording unmatched views of the outside environment. The expansive sun deck is ideal for entertaining, with large wraparound seating and lounging areas affording stunning views from a lofty elevation. An integrated submersible stern platform with a 5,000 capacity and a 3,500 lb. aft deck crane easily launch, retrieve, and stow tenders, toys, subs,  and cargo.

Magnet’s appearance is as unique as her mission. The vessel’s assertive styling incorporates chiseled lines inspired by Metal Shark’s military patrol vessels, which are designed to achieve modern naval visual deterrent requirements. Hardware is rugged and overbuilt. Angular brows lend an imposing look while shielding the vessel’s expansive windows from the sun. Exposed architectural elements and an industrial-grade finish, designed for extended operation with minimum maintenance, combine to convey the vessel’s no-nonsense demeanor.

The first M48, “Magnet,” launched in 2020, with a bespoke arrangement designed to meet the unique requirements of her owner. Magnet has been configured with a master cabin, a VIP cabin, and three guest cabins.  However, each offering in the Metal Shark Yachts lineup may be fully customized to suit the unique requirements of the owner. With its enormous 393 meters (4,230 square feet) of interior living space, M48 can easily be configured to accommodate additional guests or crew. To begin the process of configuring your very own Metal Shark Yacht, Contact Us today.


Principle Dimensions Length: 48 meters / 158′ Beam: 12 meters / 39′ Draft: 2 meters / 6.7′

Performance: Long Range: 11,000 NM @ 10 Knots Cruise: 4,500 NM @ 17 Knots Sprint: 2,500 NM @ 23 Knots Lightship Full Speed: 27 Knots

Propulsion: 2 x MTU 16V2000M96L with SCR (1939 kw / 2600 BHP)

Fuel Capacity: 110,000 Liters / 29,000 US Gallons

Displacement: Lightship: 240 Metric Tons Full Load: 350 Metric Tons

Tonnage: US Gross Register Tonnage: 290 US Net Tonnage: 197 ITC Gross Tonnage: 653 ITC Net Tonnage: 195

Submersible Stern Platform: 2268 kg / 5,000 Lbs Lift Capacity

Download Detailed Specifications


Model range, m30 • 30 meters / 100', m48 • 48 meters / 158', m70 • 70 meters / 231'.

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Catamaran Hull Design

  • Post author By Rick
  • Post date June 29, 2010
  • 2 Comments on Catamaran Hull Design

steel hull catamaran

Part 1: Notes from Richard Woods

Since the America’s Cup experimented with going multihull, there’s been a lot of interest in catamaran performance and the catamaran hull designs that define performance. Many guys are investigating whether to buy a catamaran or design and build their dream boat. Let it be said here that building a large catamaran is not for the faint of heart. People begin building 100s of boats a year, yet few are ever completed, as life always seems to have a way of interfering with a good boat build. 

Never the less, since the rest of this website is about selecting and buying a boat , it only seems fair to have at least one webpage that covers catamaran design. This page contains notes on boat hull design goals and an accompanying page from Terho Halme has mathematical formulas used in actual catamaran hull design. It has become a popular research stop and an important reference to the catamaran design community.

The content of this page was reproduced from the maestro of Catamaran designs, renown British naval architect, Richard Woods, who not only designs catamarans, he sails them across oceans…. repeatedly. He has a lot to say on the subject of catamaran hull design.

“…When it’ all said and done, the performance of a sailing catamaran is dependent on three primary specs: length, sail area and weight. If the boat is longer it generally means it’ a faster boat. If she has more sail area, it means she’ a faster boat and if she’ light it means she’ a faster boat.  Of course, there are limits: Too much sail area capsizes the boat in brisk winds. If the boat is designed too light, she will not take any kind of punishment. Too slim a hull design and the boat becomes a large Hobie Cat capable of only carrying your lunch. Of course, too long and large and you’d have to be Bill Gates to afford one. Then there are lot of additional and very important factors like underwater hull shape, aspect ratios of boards and sails, wet deck clearance, rotating or fixed rigging and so on….” Richard Woods

All Catamarans are not equal, but all sailboats have two things in common: They travel on water and they’re wind powered, so the Catamaran design equations in the 2nd part should apply to every catamaran from a heavy cruising Cat to a true ocean racer.

Richard Wood’s comments on catamaran design:

We all know that multihulls can be made faster by making them longer or lighter or by adding more sail. Those factors are the most important and why they are used as the basis of most rating rules. However using just those figures is a bit like determining a cars performance just by its hp and curbside weight. It would also imply that a Tornado would sail as fast forwards as backwards (OK, I know I just wrote that a Catalac went faster backwards than forwards)

So what next?? Weight and length can be combined into the Slenderness Ratio (SLR). But since most multihulls have similar Depth/WL beam ratios you can pretty much say the SLR equates to the LWL/BWL ratio. Typically this will be 8-10:1 for a slow cruising catamaran (or the main hull of most trimarans), 12-14:1 for a performance cruiser and 20:1 for an extreme racer.

So by and large faster boats have finer hulls. But the wetted surface area (WSA) increases proportionately as fineness increases (for a given displacement the half orange shape gives the least WSA) so fine hulls tend to be slower in low wind speeds.

The most important catamaran design hull shape factor, is the Prismatic Coefficient (Cp). This is a measure of the fullness of the ends of the hull. Instinctively you might think that fine ends would be faster as they would “cut through the water better”. But in fact you want a high Cp for high speeds. However everything is interrelated. If you have fine hulls you can use a lower Cp. Most monohulls have a Cp of 0.55- 0.57. And that is about right for displacement speeds.

However the key to Catamaran design is you need a higher Cp if you want to sail fast. So a multihull should be at least 0.61 and a heavy displacement multihull a bit higher still. It is difficult to get much over 0.67 without a very distorted hull shape or one with excessive WSA. So all multihulls should have a Cp between 0.61 and 0.65. None of this is very special or new. It has been well known by naval architects for at least 50 years.

There are various ways of achieving a high Cp. You could fit bulb bows (as Lock Crowther did). Note this bow is a bit different from those seen on ships (which work at very specific hull speeds – which are very low for their LOA). But one problem with them is that these tend to slam in a seaway. 

Another way is to have a very wide planing aft section. But that can increase WSA and leads to other problems I’ll mention in a minute. Finally you can flatten out the hull rocker (the keel shape seen from the side) and add a bustle aft. That is the approach I use, in part because that adds displacement aft, just where it is most needed.

I agree that a high Cp increases drag at low speeds. But at speeds over hull speed drag decreases dramatically on a high Cp boat relative to one with a low Cp. With the correct Cp drag can be reduced by over 10%. In other words you will go 10% faster (and that is a lot!) in the same wind and with the same sails as a boat with a unfavorable Cp. In light winds it is easy to overcome the extra drag because you have lots of stability and so can fly extra light weather sails.

The time you really need a high Cp boat is when beating to windward in a big sea. Then you don’t have the stability and really want to get to your destination fast. At least I do, I don’t mind slowly drifting along in a calm. But I hate “windward bashing”

But when you sail to windward the boat pitches. The sea isn’t like a test tank or a computer program. And here I agree with Evan. Immersed transoms will slow you down (that is why I use a narrower transom than most designers).

I also agree with Evan (and why not, he knows more about Volvo 60 design than nearly anyone else on the planet) in that I don’t think you should compare a catamaran hull to a monohull, even a racing one. Why chose a Volvo 60/Vendee boat with an immersed transom? Why not chose a 60ft Americas Cup boat with a narrow out of the water transom?? 

To be honest I haven’t use Michelet so cannot really comment. But I have tested model catamarans in a big test tank and I know how inaccurate tank test results can be. I cannot believe that a computer program will be better.

It would be easy to prove one way or the other though. A catamaran hull is much like a frigate hull (similar SLR, L/B ratios and Froude numbers) and there is plenty of data available for those. There is also a lot of data for the round bilge narrow non planing motorboats popular in the 1930’-50’s which again are similar to a single multihull hull.

One of the key findings I discovered with my tank test work was just how great the drag was due to wave interference between the hulls. Even a catamaran with a modern wide hull spacing had a drag increase of up to 20 % when compared to hulls at infinite spacing. One reason why just flying a hull is fast (the Cp increases when you do as well, which also helps). So you cannot just double the drag of a single hull and expect to get accurate results. And any speed prediction formula must include a windage factor if it is to give meaningful results.About 25 years ago we sailed two identical 24ft Striders next to each other. They were the same speed. Then we moved the crew of one boat to the bow. That boat IMMEDIATELY went ½ knot faster. That is why I now arrange the deck layout of my racing boats so that the crew can stay in front of the mast at all times, even when tacking or using the spinnaker.

I once raced against a bridge deck cabin catamaran whose skipper kept the 5 crew on the forward netting beam the whole race. He won.

Richard Woods of Woods Designs www.sailingcatamarans.com

  • Tags Buying Advice , Catamaran Designers


Owner of a Catalac 8M and Catamaransite webmaster.

2 replies on “Catamaran Hull Design”

I totally agree with what you say. But Uli only talk sailing catamarans.

If only solar power. You need the very best. As limited watts. Hp.

The closer to 1-20 the better.

Closing the hulls to fit in cheaper marina berth. ?

You say not too close. But is that for sailing only.

Any comment is greatly appreciated

Kind regards Jeppe

Superb article

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The Planing Power Catamaran: A Different Kind Of Cat


Planing powercats deliver the high speeds dayboaters and weekend anglers crave — but without so much pounding in choppy seas.

Rear view of a dual hull catamaran with two 200 horsepower outboard engines, a bimini top with fishing rods attched to it moored  in turquoise blue water

The air cushion ­created between the two hulls dramatically reduces wave impact at running speeds. (Photo: World Cat)

Powercats are different beasts than sailing cats, and the powercats you're most likely to see on your local waters are those in the 20- to 40-foot range (like my 22-foot Glacier Bay). Unlike the big cruising powercats, which are more like cat trawlers with top ends maybe a little over 20 mph, smaller cats have planing hulls that perform much like today's modern powerboats.

Depending on the engine package, there are a few cats that top out in the lower 30s, lots in the lower 40s, some in the 50s, and a few that break 70 or even 80 mph.

While a similar length monohull may have a 40-mph cruising speed in a 2-foot chop, the monohull captain will pull back the throttles and cruise at 30 to avoid being beaten up. The cat guy, on the other hand, may be able to keep on doing 40 thanks to the smoother ride. But having two hulls underfoot does create some interesting similarities in how these different types of boats react to input from the helm. So you'll see a few of the tips here mirror those used for sailing or cruising catamarans. Whatever type of cat you may be captaining, remember the following:

  • Center the wheel and use only the throttles to control the boat. Powercats have their engines exceptionally widely spaced apart, and are far more responsive than monohulls when steered via throttles. Generally speaking, turning the steering wheel will only serve to reduce the effectiveness of working the throttles. This, of course, is assuming you have two engines. There are a few rare cats with one engine.
  • At identical rpm, the engine in forward will create more thrust than the engine in reverse. So even if the throttles are set evenly when opposed, the boat will likely slide forward a bit as opposed to spinning in its own length. As a result, when attempting to speed up the maneuver it's usually best to favor giving the reversed engine extra oomph as opposed to the one in forward (assuming you don't want to move forward while turning the boat).
  • Check the speed and direction of the wind before docking , and remember that some cats, particularly those with low draft, can be blown around more easily than many monohulls as there may be less hull below the waterline.
  • When docking in a new slip for the first time with lines that haven't been preset, bear in mind that once you're docked, securing the boat can be difficult in some situations because few powercats have centered cleats. Most will have a single cleat on either side, in some cases obstructed by a bow rail and/or pulpit, which can make crossing lines difficult.
  • Never shut those engines down until all the lines are secured . Again, remember that many cats can get blown out of kilter faster than the average monohull, and if you don't have lines preset, it may take a moment to figure out how to best secure them. Many a captain has done a perfect docking job and then shut off the engines, only for a gust of wind to push the boat right back out of the slip before the lines can be tied. Keep those engines running until the boat is 100% secure so you can apply power, if necessary, to maintain position.

Why Two Hulls?

Like all boats, catamarans come with distinct advantages (smooth ride, draft), and areas of compromise (docking, turning). Regardless of design aesthetics, the first question is usually: Why two hulls?

Mike Myers, vice president of product development for World Cat explains: "Catamaran hulls experience little to no drag or resistance to get on plane, resulting in greater fuel economy. They have a steady rise in speed and fuel burn with little to no spikes in fuel consumption."Planing powercats have a unique trait — which many cat lovers consider the top advantage over monohulls — the impact-absorbing cushion of air created by a compression tunnel between hulls.

And when it comes to beam, catamarans' parallel hulls create reliable stability, which helps to avoid heeling and capsizing, and greatly reduces the vessel roll at rest and at trolling speeds.

"Many boats are primarily designed around comfort for the captain. This usually means anyone at the front or sides of the boat takes most of the jostling,"Myers says. "The catamaran-style hull delivers ride comfort, smoothness, load distribution, and stability."That stability draws anglers to powercats of typically 20 to 40 feet; and cruisers to sailing cats 40 to 60 feet and beyond.

— Rich Armstrong

Taming The Cat

When it comes to handling powercats in open waters, the most important thing to remember is that all boats are different. Just as you wouldn't lump the handling characteristics of all monohulls together, the same goes for powercats. But many have a few common traits to consider.

  • Some powercats have relatively low buoyancy in the bow compared to monohulls, as many have very narrow hull entries . As a result, in some cases, idling into a sea can allow waves to break over the bow. Gaining some headway so the bow rises a bit and packs air into the tunnel can alleviate the issue.
  • Some planing powercats will run smoother at faster speeds than slower speeds, as they compress air in the tunnel between the two hulls. In these cases, speeding up may actually provide a more comfortable ride in some sea states as compared to slowing down. Depending on your boat, its tunnel may result in other differences from the monohull that you may be familiar with. Learning about these will improve you experience.
  • Some powercats display a "snap roll,"which is a very fast righting motion that can rock the boat uncomfortably, especially when drifting in a beam sea. In these cases, people who may want to drift often (such as anglers) will sometimes deploy a drift sock off the bow to reduce rocking and rolling.

Man wearing a white long-sleeve t-shirt fishing off the bow of a power catamaran as it cruises through the water

Photo: World Cat

  • In general, powercats are often more weight-sensitive than monohulls, especially when the bow is loaded down . It's always best to be aware of how you're loading your boat, and if the tunnel is slapping or the bow is digging into waves, consider shifting weight aft.
  • Some powercats, particularly older models, lean out in a turn rather than banking in. There's no way to eliminate this phenomenon (although trimming up an outboard engine when initiating a turn may reduce it a bit), so it's important to give passengers a warning to hold on before making any aggressive maneuvers.
  • "Sneezing,"or blowing a puff of mist out the front of the tunnel that the boat then runs through (getting everyone aboard damp), is a phenomenon associated with some powercats. In many cases, trimming the bow up a bit will significantly reduce or even eliminate sneezing.

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Steel Boats: A Strong Alternative

  • By Geoff Payne
  • Updated: August 7, 2002

Adventure cruising down Chile’s exciting southern waterway, we chose to make a side trip up one of the many fiords. Like most, this one was uncharted. “Must be as deep as the hills are high around us,” Margaret and I agreed. The crew of an approaching local fishing boat waved enthusiastically as we tacked from shore to shore against a fine breeze.

Those fishermen were really waving their hands in the air at us. “Guess they’ve never seen a sailboat with such good windward ability,” I thought as we left them rapidly astern. If we hadn’t dusted them so completely, perhaps we would have seen their hands go down onto their heads and then over their ears. Full sail and at some seven knots of boat speed, 13 tons of Skookum plowed onto a pile of sharp glacial boulders lurking below the surface.

Was the boat holed due to this colossal blunder? Was the keel parted from the hull? Was the rudder torn off? Was that the end of our cruise? Well, there was a loud bang, we felt the cockpit rapidly rise then suddenly fall, but on we sailed, red-faced and with sails luffing to slow us down. Skookum’s full keel tapers down to a 2 1/2-inch-diameter solid-steel bar. That and the heavier keel plating probably made more impression on the rocks than the rocks did on us. A boat of other material could have sustained trip-terminating damage. Once again, my decision to build in steel had paid off.

Joshua, Williwaw, Damien II: These famous steel cruisers bring to mind high-latitude epic trips, often among ice. But steel is not just for extremist cruisers. As a matter of fact, the finest steel hulls are passing you by, indeed overtaking you under sail. Only you don’t realize they’re made of steel.

On Skookum’s cabin table is a small offcut from the hull plating. It’s often passed around among visitors aboard. “Sure is strong,” folks say, “but isn’t it heavy?” Skookum displaces 28,000 pounds, which is on the heavy side for a 40-footer. But there are respected fiberglass and wood designs of similar size that are heavier still.

They say lighter is faster; it’s true. When it comes to extended cruising, though, the rules are not that simple. A cruising family accumulates literally tons of weight aboard. A serious cruising boat easily could contain over 4,000 pounds of fluids, spares, tools, literature, outboards, and other provisions. That kind of weight stresses and hampers a lightweight craft. The modern steel-hulled cruising boat will be of generous displacement, proportions that will accept a large payload without loss of performance.

Your cruising boat must have good performance. It should tack smartly, carve along to windward at six or seven knots and surge before the trade winds, leaving a straight white wake. Any properly designed, medium- to heavy-displacement sailboat with a big spread of well-cut sails ought to have sparkling performance. (The 1970s saw some successful steel racers.)

Margaret and I have short-tacked slalom courses up narrow buoyed channels, eased sheets to race afternoon sailors, and logged some 180-mile days at sea in Skookum; all this with a displacement/length ratio of 450. That bit of weight in our steel construction equals a lot of comfort on the ocean — especially in rough weather.

No one doubts steel’s strength. It takes over 30,000 psi of force to deform it. Steel is an “orthotropic” material; that means it’s equally strong in all directions. Try to bend or rip a circle of steel any which way you like, it won’t give in any easier. A piece of wood will split down the grain. Wood is thus an “isotropic” material — stronger in one direction. Isotropic materials (including fiberglass, which has extra thickness roving here and there) are very efficient for boatbuilding because their strengths can be aligned to counteract predictable forces of water and wind. This results in a far lighter structure. Even though a piece of deck steel need only support your dainty weight, the minimum practical plating would still take thousands of pounds to pierce.

The end result in steel is an enormously strong structure. Skookum’s mast and rigging loads are so well resisted at deck level that our lee shrouds barely slacken, even under full sail and hard on the wind.

Of major concern to the designer of an all-steel sailboat is the weight of the steel superstructure. Don’t expect to find apartmentlike accommodations inside a steel-decked offshore cruiser, for that would raise the center of gravity unacceptably. The thickness of any framing also represents lost volume inside a steel hull. Used to good effect, it becomes valuable insulation, covered with paneling. Because structural bulkheads are seldom required in steel hulls, cabin layout can be very flexible. Free of constraints inside Skookum, I created a wide-open, bright and light-filled interior. Without fail, newcomers aboard remark upon how roomy the boat feels belowdeck.

Steel sailboat design has come a long way in recent years. Two aspects of the preceding paragraph have come under rigorous review as designers and manufacturers constantly come up with better steel craft. First, the superstructure need not be made of steel. Secondly, in some cases, the framing can be done away with.

Once upon a time a steel hull might have looked pretty much like a wood one under construction: ribs galore. To support large expanses of steel of minimum thickness and to keep it beautifully smooth and fair, light framing (transverse and longitudinal) is definitely required. Building a fair, curve-plated, round-bilged metal hull is a skill and an art — a task for the professional boatyard. However, if the curved cross section of a sailboat is approximated in straight lines, then the plating of the whole hull is considerably simplified. The fore-and-aft joint lines between plates are called “chines.” The smooth-looking sphere that is a beach ball is actually made up of once-flat tapered strips; each seam is a chine. Done right, a multi-chine steel hull is both easy to build and puts a sweet curve or two along the topsides of that vessel. But it’s a challenge on the drawing board. Done poorly, the chines appear sudden and awkward and make for a boxy looking sailboat.

Chines also introduce lines of strength into the hull (a bit like the way a floppy sheet of paper folds into a sound little aircraft). This has led designers to say, “Aha. Maybe we don’t need the frames!” Indeed it can be done, and there are plenty of such designs available. Chined, frameless hulls do require heavier plating, so there is no great weight savings. “Frameless” construction is a hotly debated topic among metal-boat designers and builders. In fact, Skookum’s chines are strengthened by longitudinal stringers, and floors in the keel provide transverse support. To completely forego all framing yet still adhere to responsible engineering principles would render a small boat heavy indeed.

Having mastered the multi-chine concept, designers and builders saw the opportunity to go one better: eliminate at least those chines visible above the waterline by introducing a “radius chine,” a narrow curved piece of steel that disguises any sudden turns in the plating. So long as that piece of steel can be cut from either a cylinder or a cone, the task is not too hard. In fact, the whole hull can be plated in “conically developed” shapes (frames required though). Steel boats like these are the ones sailing right by you looking like molded fiberglass.

Steel can be worked into nearly any shape imaginable. Clipper bows, canoe sterns, deep fin keels, tumblehome topsides, bowsprits or reverse transoms can all be achieved at commensurate cost. The skeg supporting the steel cruising boat’s rudder can be made so strong that the arrangement could hardly be considered vulnerable to damage by floating objects. Skookum’s stern even incorporates a welded tab and stopper arrangement to support the rudder in the event of the hove-to boat being thrown backward by a big sea.

Welding allows the creation of fabulous custom work on deck. Stainless steel bollards, chain plates, towing eyes, lifting lugs, vents and fillers can all be elegantly incorporated into the deck in an utterly waterproof manner.

Even the thinnest practicable steel plating (about 7/64-inch, or 12-gauge) is too heavy a material for a sailboat much less than 30 feet in length, hence you’ll find few really small steel cruisers. Any thinner plating creates problems with welding, maintaining a fair shape and corrosion tolerance.

Stock plans in steel for popular-size (35-foot to 45-foot) cruising boats generally show a medium- to medium-heavy displacement craft with average internal accommodation. These plans cost from $500 to $1,500, reflecting a wide variation in the amount of information given. Full-size templates for plating are even available with some designs. Very serious consideration should be given to the selection of the design: The one to two percent of the finished value of your project that you invest in plans could be 100 percent responsible for ultimate success…or disappointment. And you won’t find out until the first day’s sail. Designers’ work is best not to be messed with — generally it’s not on the page if it’s not important. A custom design in steel could run to 10 percent of the boat’s value.

Chined construction, a method that greatly simplifies hull plating, is an attractive option for amateur builders. With little more than a welding machine and good cutting and handling equipment, a steel hull can be backyard built. Once I had learned how to handle the long pieces of steel properly, I found the hull construction to be most rewarding. Sparks flew, there was smoke and grit, but in essence it was a bit like sewing: I made Masonite patterns for each strake, traced around them and cut the material to shape, tacked it onto the upside down temporary frame, then finally seamed it all together. Welding is so immensely and immediately strong that I was as convinced then of the boat’s colossal strength as I am now, 50,000 miles later. Full-strength welding meant I could carry out 100 percent corrections of occasional cutting errors.

What About Corrosion?** Talk of steel and the word “rust” comes up straightaway. Rust is a chemical reaction and salt water speeds it up, but not as much as you would think. Ice scraped the paint off Skookum’s waterline about a meter back from the bow. Although I didn’t get around to touching it up until nearly a year later, no major harm was done to the plating. What worried me more was rust inside the hull, in the hidden corners of the bilges. Only after four years of hard sailing did we remove the cabin sole (wisely, I made it all demountable) and after a thorough scrub, we found areas of scratched paintwork. Nothing serious, nor structural — just awkward to sand and touch up.

The steel deck, unlike the hull, is not only continually doused in salt water, but also trafficked and abraded. Anchors, chain, winch handles, harbormasters’ boots — they inevitably knock off paint. Very soon, out weeps a trickle of brown. But at least you can see it! Unlike rot or ultraviolet deterioration or osmosis, rust gives itself away practically the day it starts. It’s not difficult to remedy, just tedious.

On Skookum we have some nuisance rust spots that repeatedly need rubbing back and touching up. Repainting means a full four or five coats of touch up, so the process is a protracted one. In every case, these bits of rust around hatches, coamings, stanchions and winches could have been avoided had I done things differently in the first place. Companies well experienced in steel boat production have developed excellent detailing on deck.

Given that recurring rust problems occur on deck, and that a boat doesn’t sail upside down, why then not construct the deck of something else? It’s called composite construction and it’s commonplace. Strong plywood decks and cabins can be built over steel framing. Epoxy and fiberglass take care of the sealing and finish. Aluminum decks can be married to steel hulls. Composite construction has other merits, such as less weight and less magnetic interference. (Tons and tons of steel certainly have an effect on a compass. Our classic five-inch-diameter steering compass stands on its own binnacle and was some 20 degrees off upon installation. Standard correctors inside the unit reduced this to a known five degrees on east and west headings. Electronic compasses can have sensors placed inside the mast or on a radar post and thus removed from steel’s magnetic clutches.)

Corrosion comes in another and more wicked form: electrolysis. Put nearly any other common metal underwater near steel and a battery current flows. More often than not it is steel that loses the electrons. Little volcanoes of corrosion erupt on unprotected steel, and these inflict damage much faster than rust. Electrolysis is a threat to any kind of boat, but especially to metal-hulled ones.

All steel craft sport little zinc pads on the keel, rudder and propeller shaft. These “sacrificial anodes” corrode instead of the hull, so must be maintained. Corrosion vigilance is the price one must pay for the reassuring strength of steel.

The corrosion specter heavily devalues older steel boats, especially if a bit of the brown stuff is visible. Boats that have not had the protection of modern paint systems might be picked up, for a “steel.” If you’re planning to recondition an older steel craft, first establish if you can gain access to all the steel surfaces. Even then the cost of dismantling, preparation and recoating will be considerable.

Coatings Offer Excellent Protection** Rust and electrolysis can only get a grip on bare steel. Coatings have advanced in recent decades and offer excellent protection. One system coats the sandblasted steel with coal tar combined with epoxy. Another paint is substantially zinc. Or, the whole boat can be “flame sprayed” with aluminum or zinc — the ultimate treatment (see the “Save The Steel” sidebar, following). Most seagoing steel is protected mainly by epoxy paint. As many as nine coats go on — primer, high builds, hard and gloss coats (polyurethane). It’s a significant investment in paint, but very effective and attractive.

That little piece of plating that we keep by the cabin table to show visitors was cut out of the finished transom. The thickness of paint buildup seen in the cross section is impressive. In fact, we’ve taken to saying we’re sailing around the world in an epoxy boat lined with steel. These paints ought to last a very long time. As long as the steel remains coated, our boat is going to be around longer than we are.

One other coating proven on steel hulls is sprayed polyurethane foam insulation. About 1 1/2 to two inches of this closed-cell substance, sprayed inside from the turn of the bilge up and over the deckhead, transforms a clammy, tinny chamber into a quiet refuge, cozy or cool as required. It’s superb insulation that retains or repels heat, eliminates condensation, dampens deck noises and sticks tenaciously to (lightly painted) steel, keeping air and water from ever initiating interior rust.

There’s an image of steel boats being dank and clammy belowdeck. Perhaps those that are uninsulated are that way. In fact, the coziest and sweetest smelling cabins I’ve experienced have been aboard steel craft. The Mexican “lancha” drivers used to think we were “locos” to live inside a black steel hull…until they came below and found it to be airy and cool. Spray foam has kept Skookum comfortable to live in at all latitudes.

The Security Issue** Steel sailboats are over-engineered — for wind and water forces, that is. Can the vessel to which you entrust your family’s life be too strong? What if on a calm and sunny day you tied up, went into town, and returned to find the local ferry had T-boned your boat into a concrete wharf? It happened. That metal sailboat completed its circumnavigation — a bit dented, that’s all.

In or out of the water an all-steel sailboat with polycarbonate hatches also will be a formidable barrier to burglars, even bullets. If seacocks connect to metal standpipes extending above the waterline and shafts have metal stuffing boxes, then a steel craft might survive an internal explosion or fire. Charred, but still floating.

Our boat’s nearly invincible strength had to become our insurance policy in far southern latitudes — no underwriter would cover us. So why are we shopping around for coverage now that we’re back in busier, foggier waters? Afraid of being run down? On the contrary — with 13 tons of momentum, our pointy-ended boat could sink something 10 times its size. We need liability insurance.

With such strength and so solid a feel, by providing so smooth a ride, the well-appointed steel sailboat is a Mercedes Benz of ocean cruisers. Cost is not in the upper luxury level, especially if you are home-building, for which steel is well suited. Extra expenses for the rig and proper sail area to drive such a sturdy craft is why a performance, steel sailboat is not going to be the cheapest option. In value, appearance and performance steel cruisers are right in there with equivalent-size boats made of other materials. And if it comes to the c-r-u-n-c-h, they’re incomparably stronger.

Before next you stroll the marinas, put a fridge magnet in your pocket. Slide it on to some really pretty boats — you might just get a surprise. Marine steel craft have come a long way in recent years.

———————————————————————— After taking a couple of years off from cruising to build a house, to research a biography of yacht designer (and uncle) Alan Payne and to fill the cruising kitty, Australians Geoff Payne and Margaret Hough are planning to take Skookum next summer for a tour of the Canadian Maritimes and beyond.

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Marine aluminum vs marine steel for ship hull. What to choose?

Discussion in ' Materials ' started by Edem , Apr 21, 2021 .

  • #aluminum #marine #hull

Marine aluminum or marine steel ?


Edem Junior Member

Dear forum users! Now I will bring up a topic that may seem absurd, given the stage at which I am. But this is very important to me. My friends and I are building a catamaran in Russia. We are in the midst of designing. But in a high degree of readiness. The design is being developed using marine aluminum AlMg5 (AA5056 (USA), 5056 (Japan)). The catamaran will operate in the tropical zone of the Indian Ocean in the Seychelles region. Dimensions 22 meters long by 7.5 meters wide (the length may be less by 2 meters, we will coordinate this part with the Russian regulations office, but this is a detail). It is important that the catamaran will move at a cruising speed of 12 knots + -2 knots, with a maximum speed of 18 knots + - 2 knots. In the next branch on diesel engines, we are discussing possible engines. Actually, that's why I came to the forum. So this is the problem: we build the catamaran ourselves, and aluminum is a very finicky metal. I started testing welders and submitting welds for examination, and out of 15 welders, none of them was able to make a weld without defects. And we need 3 welding posts, but so far there is only one. And since we do not have the financial ability to order the construction of a boat at a shipyard, the question of welder specialists is very important for us. I am now sitting holding my head and thinking what to do. Maybe move away from naval aluminum and switch to naval steel before aluminum is ordered? The argument is that it is easier to weld the steel hull of the ship, it is easier to control the process and the likelihood of defect (rejects) is less and we do not need an extra high-speed catamaran and we can (possibly) add 20-25 percent to the mass of the ship hull. But this will entail fuel consumption on an ongoing basis. But is it that significant? What material do you think to choose? What are their real performance and durability? How often and to what extent will these enclosures require maintenance in comparison? Is it really worth the question of the durability of the hull, taking into account modern protective case paints? Still interesting tips on how to prime, putty and paint the ship's hull? Are these one materials for steel and aluminum? So that I can compare the costs of the final hull in steel and in aluminum, of approximately the same aesthetic quality (this is also important, we all want to look at beauty, the dream is always beautiful It so happened that when I came to the forum to consult on engines, I thought about the material of the hull- something that I needed to think about from the very beginning. But better late than never!) Thanks to all the forum members, you are creating so much useful content! For me, as a person from Russia, where there is no tradition of private shipbuilding, this is just a fantastic resource! I will be glad and grateful for every opinion! P.S. We cannot work with composite materials for build the ship hull, let's not consider them. Only steel and aluminum.  


TANSL Senior Member

If you are not able to properly weld aluminum the only option you have is steel. Thus, considerations about consumption, maintenance, etc. they go into the background. Why are you going to study an option, aluminum, which is out of your reach?. The boat will be heavier with steel than with aluminum but its quality will be assured and, in addition, a good design of the structure and a good calculation of the scantlings will mean that the boat does not have more weight than it should.  

Mr Efficiency

Mr Efficiency Senior Member

Maybe you can make the hulls from steel, and the superstructure, where less than perfect welds won't be the "end of the world", from Aluminium.  

Will Gilmore

Will Gilmore Senior Member

Are you docking the boat between two aluminum hulls or between two steel hulls? In either case, I'd rather have steel.  


DogCavalry Senior Member

Welcome to the forum, Edem. Skilled aluminum welders seem to rare everywhere. As TANSL points out, there's no decision to be made. If you can't get a proper aluminum weld, steel it is. Turn your attention that way, and forget Al.  


Barry Senior Member

I find it hard to believe that a certified welder cannot make up an aluminum joint. While welding aluminum requires perhaps a bit more care, especially in thickness less than 5 mm ( I realize that many smaller boats are welded using 3 mm) when you begin to get into thicker pieces the welding gets easier to make a sound joint with Mig. Perhaps what is more important is the sequences in welds and some other processes. The advantages of aluminum is that the inside does not have to be maintained as steel has to, it is lighter than steel though more expensive. With aluminum you will need more attention to corrosion, dissimilar metals issues but aluminum can be cut with normal woodworking equipment. You say that you are building the boat yourself. You could learn how to tack weld up plates and extrusions in about 6 hours of instruction and do the tacking yourself then have a competent welder do the final welding. The welder would be able to properly tack adjacent to yours if necessary, zip cut out yours, and do the welding. More time is spent fitting up a hull than the actual welding itself.  


bajansailor Marine Surveyor

I have been involved in the past with the design and construction of a 15 metre aluminium power cat (the one in my avatar), and a 12 metre steel power cat. Both were built 20 years ago. The aluminium one is still working well, and is in good condition generally, and has not needed any costly re-fits yet. The owner of the steel cat decided to go with steel rather than aluminium on the basis of initial cost of construction. Yet when we were doing the outfitting he was amazed by the cost of all the paint that was required to protect the steel - everything has to be painted, inside and out, otherwise it rusts away very quickly. Especially in comparison to the ally cat, where only the hull exterior below the waterline and the deck was / is painted. And the poor steel cat is now sitting ashore, rusting away happily, despite the 3rd owner starting a major re-fit about 10 years ago, and then giving up after having spent a small fortune on her. I would strongly recommend to any potential future owner of a catamaran that is less than say 24 metres in length here to go for an aluminium cat rather than steel. Especially so if you want the hull shapes to be efficient, and fairly slender. We do have good aluminium welders here which is a very strong positive factor. But Barry has suggested some good ways of achieving 'proper' welds in his post above. Edem, can you post any sketches that you have created so far of your new design please?  


comfisherman Senior Member

Its 2021, I can get aluminum specific welding equipment of high quality for a very small percentage of what this project will cost. To extreme remote Alaska, certainly its possible in Russia. The average semi handy individual can come up to speed on an acceptable weld in several weeks of instruction. Right now enough 5086 marine plate is going to be a weeks to months lead time, would seem like plenty of time to get some weld practice in. A miller 255 pulse mig with an aluma pro push pull is under 5500 usd. Dunno about global availability but there has to be a global equivalent machine. With pulse mig and and a mid tier push pull, most folks learn fast. Guessing the cost of even a few machines will look small compared to that much alloy. I've not bought 5086 since sept of 2020, but even then it was getting expensive. I sold a commercial aluminum boat in 2014, it had some galvanic issues over the years but was a good boat. Still kinda miss that boat. I sold a steel boat of similar size in 2020, and sold the ingersoll rand compressor and blast pot the next day..... I've not missed either the steel or the blaster needed to keep the steel from rusting.  

Ad Hoc

Ad Hoc Naval Architect

Edem said: ↑ ....Maybe move away from naval aluminum and switch to naval steel before aluminum is ordered?.... Click to expand...
TANSL said: ↑ Why are you going to study an option, aluminum, which is out of your reach? Click to expand...
bajansailor said: ↑ Edem, can you post any sketches that you have created so far of your new design please? Click to expand...
Ad Hoc said: ↑ Since they may just be poor welders! Click to expand...
Edem said: ↑ Mr Efficiency, I am considering this option. Make the critical part of the boat from steel, and the superstructure from aluminum. The hulls of the sideboards and the bridge are made of steel, as they are subject to a high load on twisting and slamming, and the superstructures are made of aluminum. But the question of combining different metals is also very complicated. Could you tell me about this? Click to expand...
Edem said: ↑ ...The design is being developed using marine aluminum AlMg5 (AA5056 (USA), 5056 (Japan)).... Click to expand...
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baeckmo Hydrodynamics

Edem said: ↑ Ad Hoc, they explained to me that this is due to the fact that we have very few production facilities in Russia where the skills of aluminum welding are required in the conditions of welding aluminum hulls of ships. There is also a question about the welding mode and the welding current. It may indeed be easier to train welders .. Here you have to think .. Click to expand...


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  • 2Hulls Inc. (Catamaran, power catamaran & trimaran broker dealers, Fort Lauderdale, Florida)
  • Building the Aluminum Catamarans Osram VII and Osram VIII
  • Advanced Multihull Designs (AMD, high speed passenger and vehicle ferries)
  • African Cats (Builder of cruising sail and power catamarans, Amstelveen, the Netherlands)
  • All American Marine (Aluminum Teknicraft catamaran work, passenger and pleasure motorboats, Bellingham, Washington)
  • Alwoplast (Builder of large sail/power multihulls, repairs, Valdivia, Chile)
  • AmeraCat Custom Catamarans (Builder of commercial or recreational offshore fishing catamarans, Ft. Pierce, Florida)
  • American Proas, 1898-1998
  • American Sail (Builder of Aqua Cat catamarans, Charleston, South Carolina)
  • Aquidneck Custom Boat Builders (Construction, repair and refit of multihulls to 30' beam, composite or other materials, fabrication of composite components, Bristol, Rhode Island)
  • The Arctic Ant Aeroboat (Amphibious tetramaran airboat for Arctic conditions, "Don't let the Arctic conditions stop you from doing what the Titanic couldn't, there are no weather conditions unaccessible for the Arctic Ant ," Larsmo, Finland)
  • Aspen Power Catamarans (28-40', Burlington, Washington)
  • Austal Group (Builder of aluminium vessels including fast ferries, patrol boats, cruise and live-aboard vessels and private motor yachts, Henderson, Western Australia)
  • The Austin Outrigger Canoe Club (Lady Bird Lake, Texas)
  • Aventure Catamarans (Power and sailing catamarans, Monaco)
  • Bailey Custom Boats (Wooden pontoon boats, Statesboro, Georgia)
  • Bell Composites, Inc. (Builder of Offshore Catamarans, Powercat motor catamarans, outrigger canoes, Jupiter, Florida)
  • Bennington Pontoon Boats
  • BoatSmith (Builder of cruising catamarans, West Palm Beach, Florida)
  • The British A Class Catamaran Association
  • The British Columbia Multihull Society (BCMS)
  • Build a Catamaran (Catamaran building logs)
  • Building a Woods design Pixie Catamaran in Uruguay (Jeremy Bernal builds a beach cat)
  • The Canadian Dart Association (18' catamaran)
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  • The Catamaran Company (New and used catamarans, sailing vacations, and catamaran services, Fort Lauderdale, Florida)
  • Catamaran Cruisers (Fiberglass catamaran houseboats, Columbia, Tennessee)
  • The Catamaran Racing Association of Michigan (CRAM)
  • Catamaran Sailor Magazine ( ("A NEWSpaper that covers any and all news concerning beach cats")
  • The Catapult Inflatable Catamaran Class Association
  • C-Dory (Builder of TomCat � power catamarans, Auburn, Washington)
  • Choy Designs (Multihull luxury yachts)
  • Chris White Designs (Cruising multihulls)
  • Coast Catamarans (Developer of the Coast 50 akuminum cruising catamaran, Marseille)
  • Corsair Marine, Inc. (Ian Farrier-designed folding, trailerable trimarans, Ho Chi Minh City, Vietnam)
  • Custom Fiberglass International (CFI, builder Isotope and Cheshire sailing catamarans, Durham, North Carolina)
  • Cypress Cay Pontoons (Custom, luxury and fishing pontoon boats, Fort Wayne, Indiana)
  • Dick Newick (Trimaran, catamaran & proa designs)
  • The Dick Newick Proa Cheers (Third in the 1968 Transat)
  • Dragonfly Sailboats (Folding trimarans 6-12 meters, Fredericia, Denmark)
  • ElectraCraft (Builder of electric powered launches and pontoon boats, Westlake Village, California)
  • Endeavour Catamaran Corporation (Cruising catamarans, Clearwater, Florida)
  • Eric Henseval Yacht Design (Sailing multihulls, France)
  • Far East Boats (Manufacturer of sailing multihulls, Jiangsu, China)
  • The Farrier/Corsair Trimaran Discussion Group (Discussion of the multihull sailboats designed by Ian Farrier)
  • Farrier Marine Inc. (Ian Farrier multihull designs)
  • FishCraft (Builder of inflatable drift catamarans, Sisters, Oregon)
  • Flaquita (Tacking proa for homebuilders designed by Joe Henry)
  • Flats � Cat (Rough water-shallow water power catamaran)
  • The Flying Proa (Article by William Alden from Harper's New Monthly Magazine , 1877?)
  • Fritz Koschmann's Bolger Double Eagle (Building a catamaran eco-tour boat)
  • Fulcrum Speedworks (Builder of UFO foiling sailing catamarans, East Providence, Rhode island.)
  • Fusion Catamarans (Kits for 40' composite sail and power catamarans, Australia & Thailand)
  • Gary Dierking's Outrigger Sailing Canoes Blog (Photos, drawings, and descriptions of outrigger canoes around the world, Gary's outrigger sailing canoe plans)
  • The Gemini Catamaran Owners Association
  • Gemini Catamarans (Cruising catamarans, Annapolis, Maryland)
  • Godfrey Pontoon Boats
  • Grabner (Maker of Happy Cat inflatable sailing catamarans, Haag, Austria)
  • Grainger Designs (Raku sailing catamarans, Sensori power catamarans, custom and racing designs)
  • Great Lakes Watercraft (Maker of MiniCat inflatable sailing catamarans, Takacat inflatable catamarans, Detroit, Michigan and Windsor, Ontario)
  • Green Dream Boats (Builder of Solliner solar catamarans, Gdynia, Poland)
  • Gunboat Multihulls (Manufacturer of large sailing catamarans, Wareham, Massachusetts)
  • Harris FloteBote Pontoon Boats (Fort Wayne, Indiana)
  • Harryproa (Plans, kits & professionally built Harry, Harrigami & Visionarry cruising proas designed by Rob Denney, Australia)
  • Hartley Multihull Designs (Sailing catamaran and trimaran plans for amateur builders, New Plymouth, New Zealand)
  • Harvey Golden's Thamakau Project (A skin-on-frame Fijian sailing proa)
  • The Hawaiian Sailing Canoe Association (HSCA, information and education on the culture of the Hawaiian sailing canoe)
  • Henny van Oortmarssen Homebuilding the F-39 Trimaran Fram in the Netherlands
  • Hobie (Manufacturer of sailing catamarans and trimarans)
  • Hoewa�a Dallas Outrigger Canoe Club (Texas)
  • Holopuni Canoes (Maker of paddling and sailing Hawaiian outrigger canoes, Tahoe City, California)
  • How to Build a Timber Outrigger Canoe (FAO online pamphlet)
  • Hydro Bikes (Pedal powered catamarans)
  • l'Hydropt�re (Speed record setting hydrofoil trimaran)
  • Incat Australia (Builder of wave piercing and conventional catamaran ferries)
  • The International A Division Catamaran Association
  • The International Small Catamaran Handicap Rating System (SCHRS)
  • The International Tornado Association
  • The James Dory Page (Building a Kurt Hughes 30' Cruising Catamaran)
  • James Wharram Designs
  • The Jarcat Catamarans Discussion Group
  • John Shuttleworth Yacht Designs Ltd. (Multihulls, power and sail)
  • Jutson Marine Design (Power catamarans, multihull sailboats, Vancouver, British Columbia)
  • K-designs (Bernd Kohler's wing in ground effect and multihull vessels)
  • Kelsall Catamarans (Designs 18-75')
  • The Kent Island Outrigger Canoe Club
  • Kevlacat Power Catamarans (Buddina, Queensland)
  • Kha Shing Enterprise (KSE, builder of Montefino catamaran motor yachts, Kaohsiung City, Taiwan)
  • Kiribati Canoes (Proas)
  • The Koehler Multihulls Discussion Group
  • Kurt Hughes Sailing Designs (Catamarans and trimarans)
  • Lagoon (Builder of luxury sailing catamarans, Bordeaux Cedex, France)
  • LeisureCat & AussieCat (LeisureCat power catamarans, marketed in America as AussieCats, Bibra Lake, Western Australia)
  • Maine Cat Catamarans (Builder of cruising sail catamarans, Bremen, Maine)
  • Manitou Boats (Aluminum trimaran pontoon boats, Lansing, Michigan)
  • Mehrrumpfboote (A German catamaran, trimaran & proa site)
  • Metz Boats (Small multihull designs and kits by Klaus Metz, Munich, Bavaria)
  • Michael Kabua's Riwuit (Toy sailing proa that won the Marshall Islands Independence Day race in 2000)
  • The Microship Project (A trailerable cruising trimaran)
  • Mike Waller Yacht Design (Stock and custom multihull designs, Australia)
  • Mr. Smith's Amazing Sailboats (The high-speed hydrofoil and multihull designs of Bernard Smith: Aerohydrofoils, Monomarans, Fliptackers and Sailloons)
  • The Multihull Association of South Florida (MASF)
  • The Multihull Boatbuilder Page (A free exchange of building and design information for simple, efficient, economic homebuilt multihulls)
  • The Multihull Centre (Multihull building and repairs, Millbrook, Cornwall)
  • The Multihull.com Forums (Discusions on everything multihulls plus sailing meetings devoted to multihulls)
  • Multihulls Magazine
  • Multihull World ("Australasia's multihull magazine")
  • MultiMarine (Used multihulls, multihull designs by Michael Leneman, Venice, California)
  • Multi Winds International (Maker of the �lan � trailerable trimaran and Extreme � catamarans)
  • M. u. H. von der Linden GmbH (Kits for Grainger and Schionning sailing catamarans, Schionning power catamarans, Wesel, Germany)
  • The National Mosquito Catamaran Council (Australia)
  • The New England Multihull Association (NEMA)
  • Newick Nautical Designs (Dick Newick, stock and custom multihull designs, Sebastopol, California)
  • New Wave Boat Company, Inc. (Maker of the Hydro Bike Explorer pedal catamaran)
  • Nichols Brothers Boat Builders (Large power passenger catamarans, Freeland, Washington)
  • Nichols Diversified Industries (Custom aluminum and steel power passenger catamarans and trimarans to 65', Freeland, Washington)
  • Nickels Boat Works (Manufacturer of WindRider & Astus trimarans, Burton, Michigan)
  • Noosa Cat (Power catamarans, Australia)
  • The Northwest Multihull Association (NWMA)
  • The Northwest Multihull Association Discussion Group (NWMA)
  • The Norwegian Multihull Association (Norsk Flerskrog Seilklubb, the national class organisation for multihull sailors, including Hobie Cat)
  • The Oahu Hawaiian Canoe Racing Association (OHCRA)
  • The Offshore Multihull Association (OMA, promoting offshore multihull classes at racing events around the world)
  • On The Wire Back Issues Online (Ezine for Hobie sailors)
  • Pacific Proa Company (Flying proas, Sausalito, California)
  • Pantawee Marine (Builder of composite multihulls, both power and sail, up to 18 meters, Thailand)
  • The Paper Tiger Catamaran International Association
  • Paritet Boats (Manufacturer of high speed aluminum power catamarans, Moscow, Russia)
  • Pedigree Cats Inc. (Custom multihulls 46-136', Raymond, Washington)
  • The Polynesian Catamaran Association (Wharram catamaran admirers club)
  • The Polynesian Voyaging Society
  • Princecraft Boats (Manufacturer of aluminum pontoon boats, Princeville, Qu�bec)
  • ProaBoat ("The web site for proa boat owners, builders, and designers")
  • The Proa FAQ
  • Proa File (Michael Schacht's online journal "focused on the multihull sailing canoes of the Pacific Islands as object lessons in sustainable design")
  • Proa Web Sites (Linklist at Pacific Proa Company)
  • ProPhish (Manufacturers of the WaterSkipper inflatable catamaran pedal boat)
  • The Queensland Multihull Yacht Club (Brisbane)
  • Q-West Boat Builders (Builder of catamaran passenger ferries up to 40m, Wanganui, New Zealand)
  • Ranger Boats (Builder of pontoon boats, Flippin, Arkansas)
  • Running Tide Yachts, Ltd. (Monohull and multihull designs with a mast-aft sailing rig and a 65' gamefishing sailing catamaran)
  • The Sailrocket World Record Speed Sailing Attempt (A British hydrofoil proa)
  • The San Francisco Outrigger Canoe Club (SFOCC, Hawaiian outrigger canoeing)
  • Scott Brown Mutihulls (Broker specializing in used Wharram catamarans and other multihull sailboats, Landrake, Cornwall)
  • SeaCycle (Pedal powered catamarans, Adrian, Michigan)
  • The Searunner Design Parnership (John Marples and Jim Brown, cats and tris, sail and power)
  • The Searunner Home Page (Fan page for Jim Brown's classic cruising trimarans)
  • The Searunner Trimarans Owners' Association
  • Sea Speed Aluminium Catamaran Design (Power catamarans, Brisbane, Australia)
  • Schionning Designs (Sailing and power mulithull plans and kits, Tea Gardens, New South Wales)
  • The Shearwater Catamaran Class Association
  • Skinny Hull Magazine (Sailing canoes and kayaks, proas and similar style boats)
  • SLO Sail and Canvas (Trampolines for production catamarans, San Luis Obispo, California)
  • Small Trimarans (A sailing community for small trimaran enthusiasts)
  • Solar Boats (Importer and distributor Solliner solar catamarans, Perth Western Australia)
  • South Bay Pontoon Boats (Middlebury, Indiana)
  • Starcraft Marine (Manufacturer of pontoon boats, New Paris, Indiana)
  • The Stiletto Catamaran Network
  • Stiletto Catamarans (Builder of small cruising catamarans, Columbia, North Carolina)
  • Still Water Design, Inc. (Ultralight motor catamarans for low wake environments, Chelsea, Massachusetts)
  • Sylvan Marine (Maker of aluminum pontoon boats, New Paris, Indiana)
  • Taipan America (Taipan and Boyer A-Class catamaran dealer)
  • The Taipan Catamaran Association Of Australia
  • Taylor Pacific Proa - An Experiment in Variable Geometry (Designs by Douglas Taylor)
  • Team Scarab Multihulls (Sailing trimaran plans by Ray Kendrick, Australia)
  • Technicomposit (Builder of high perfpormance composite multhulls, Antibes, France)
  • The Texas Outrigger Canoe Club (Surfside Beach, Texas)
  • Tiny Dancer (21' windsurfer rigged proa by Ted Warren)
  • TomCat Boats (Daysailing and sport cruising catamarans, Newmarket, Ontario)
  • Tony Bigras' Cruising Catamaran Page
  • The Toronto Multihull Cruising Club
  • The Traverse Bay Outrigger Canoe Club (Traverse City, Michigan)
  • U-Fab Pontoon Boat Kits (Pontoon boats, houseboats and floating docks, Ottawa, Ontario)
  • The Unicorn Catamaran Class Association
  • The US A-Class Catamaran Association
  • The US Formula 18 Class Association
  • Warren Multihull Designs (Ted Warren)
  • WaveWalk, Inc. (Builder of paddled catamarans, Sharon, Massachusetts)
  • The West River Catamaran Racing Association (WRCRA, weekly catamaran racing in Galesville, Maryland and on the Chesapeake)
  • Weta Marine (Builder of sailing trimarans, North Shore City, New Zealand)
  • Wharram Builders and Friends (A photo & discussion forum for Wharram design enthusiasts)
  • Whitacre Catamarans (Semi-custom performance cruising sailing catamarans, Anacortes, Washington)
  • The Windrider Trimaran Forum
  • Woods Designs (Sailing catamaran plans for home and professional builders by Richard Woods)
  • WorldCat (Builder of WorldCat, Glacier Bay Edition and Livingston power catamarans, Tarboro, North Carolina)


  1. Custom 24m Steel Catamaran Private Floating Resort: Sailing Catamaran

    steel hull catamaran

  2. 60ft Expedition Motorsailer Catamaran

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  3. Bruce Roberts, steel boat CATAMARAN plans, boat building, boatbuilding

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  4. Steel Catamaran 11m x 4m Project

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  5. Bruce Roberts, steel boat CATAMARAN plans, boat building, boatbuilding

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  6. 60ft Steel Expedition Motor Sailer Catamaran

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  1. homemade mysticC5000R RC model boat

  2. S/Y VOYAGE 34 m Steel Hull Sailing Yacht For Sale , Malta Commercial, Rina classed, Full Walkthrough

  3. Moving Steel

  4. 61′ 7″ (18.77m) Horizon Yacht SALUS Available for Sale

  5. NEEL 43 PERFORMANCE Trimaran

  6. 92' Wider 2023 NEW Eco Power Catamaran


  1. Metal Shark Yachts

    Introducing Metal Shark Yachts. These highly advanced, industrial-grade oceangoing vessels defy convention while enabling a new level of worry-free exploration and adventure. Our all-aluminum, American-made catamarans offer global range and deliver self-sustaining independence for months on end, putting the world within reach.

  2. Bering Yachts

    Bering Yachts makes steel hull expedition type trawler yachts under 24 meters, fast hydrofoil catamarans, which are Affordable superyachts, safe, comfortable and rangy. Models. ... Bering catamarans have combined the best of two worlds: stability of the cat design and luxury, quality of craftsmanship, and innovations Bering is known for. ...

  3. 9m Steel Catamaran; thoughts?

    BB260 "Steel Catamaran 9 Metre" $595.00 Length 9.0 m Displacement 6500-7500 kg Material Steel Hull Draft 0.85 m LWL 7.9 m Hull Weight 4500 kg steel Beam 3.8 m Max Speed 12 kn Motor capacity 2 x 60 hp Fuel Type Diesel Fuel Capacity 700 litres 100mm x 50 x 3mm cross beams folded plate Fabricated frames 3mm flanged plate. 30 x 3 mm stringers.

  4. Steel boats for sale

    Find Steel boats for sale in your area & across the world on YachtWorld. Offering the best selection of boats to choose from. ... hull-steel. Steel. hull-wood. Wood. 1,372 boats. Sort By: Recommended. sort-by. Recommended. sort-by. Listing Date: New to Old. ... 2025 Mansion Yachts catamaran. Request price. Engel Volkers Yachting Americas | West ...

  5. Power Catamaran Steel boats for sale

    Clear Filter Hull Material: Steel Category: Power - Power Catamaran. Location. By Radius. By Country. country-all. All Countries. Country-CN. China. Country-MC. Monaco. Country-TH. Thailand. Country-TR. Turkey. Country-US. United States. All. Alles 25 km 50 km 100 km 200 km 300 km 500 km 1000 km 2000 km 5000 km. from your location.

  6. Bering Yachts Model Range

    Bering Yachts makes different models of steel hull expedition trawler yachts, fast hydrofoil catamarans, which are Affordable superyachts, safe, comfortable boats. Models. Expedition Yachts; ... Expedition Catamarans. B60 CAT. B80 CAT In Development. Hydrofoil Supported Catamarans. Bering Marine. Want more? Useful articles for yacht lovers! No ...

  7. Bering Yachts Fleet

    Bering Yachts makes steel hull expedition trawler yachts under 24 meters, fast hydrofoil catamarans, which are Affordable superyachts, safe, comfortable boats from 2007. Models. ... Hull No.2. In build. Bering 88. Hull No.1. In build. Bering 82. In build. Bering 80. Hull No.2. In build. Bering 80.

  8. Steel boats for sale in United States

    Find Steel boats for sale in United States. Offering the best selection of boats to choose from. ... hull-steel. Steel. hull-wood. Wood. 187 boats. Sort By: Recommended. sort-by. Recommended. sort-by. Listing Date: New to Old. ... 2025 Mansion Yachts catamaran. Request price. Engel Volkers Yachting Americas | West Palm Beach, Florida. Request Info;

  9. M48

    This 48-meter, three-decked, all aluminum catamaran is a rugged and capable purpose-built oceangoing craft enabling global exploration and delivering self-sustaining independence for months on end. Among the many advantages of Metal Shark's high-efficiency Incat Crowther catamaran hull design, M48 delivers nearly twice the range of a ...

  10. Steel catamaran hull yachts

    Yachts with Catamaran Hulls of Steel. There are currently over 10,800 yachts afloat. The longest yacht in the world is Azzam, measuring 180.61m (592'7'). She was built in 2013 by Lürssen. The largest yacht in the world is Fulk Al Salamah, built by Mariotti in 2016, with a volume of 20,361 GT.

  11. Catamaran Hull Design

    If you have fine hulls you can use a lower Cp. Most monohulls have a Cp of 0.55- 0.57. And that is about right for displacement speeds. However the key to Catamaran design is you need a higher Cp if you want to sail fast. So a multihull should be at least 0.61 and a heavy displacement multihull a bit higher still.

  12. The Planing Power Catamaran: A Different Kind Of Cat

    This usually means anyone at the front or sides of the boat takes most of the jostling,"Myers says. "The catamaran-style hull delivers ride comfort, smoothness, load distribution, and stability."That stability draws anglers to powercats of typically 20 to 40 feet; and cruisers to sailing cats 40 to 60 feet and beyond. — Rich Armstrong.

  13. Steel Boats

    Stock plans in steel for popular-size (35-foot to 45-foot) cruising boats generally show a medium- to medium-heavy displacement craft with average internal accommodation. These plans cost from $500 to $1,500, reflecting a wide variation in the amount of information given.

  14. Sail Steel boats for sale

    Find Sail Steel boats for sale in your area & across the world on YachtWorld. Offering the best selection of boats to choose from.

  15. Steel Sailing Cat

    steel catamaran. Yes, a couple stopped at my marina a few years ago with their home built steel cat. ... Her core hull was constructed with aluminium. The sailing yacht superstructure is fabricated predominantly with aluminium. With a beam of 13.41 metres / 44 ft CUAN LAW has beamy size. She has a fairly shallow draught of 1.65m (5.4ft).

  16. Custom boats for sale

    hull-steel. Steel. hull-wood. Wood. 1,144 Custom Yachts. Sort By: Recommended. sort-by. Recommended. sort-by. ... This builder offers boat hull types including displacement, deep vee, monohull, catamaran and modified vee that are generally used for traditional, time-honored endeavors such as overnight cruising, sailing, day cruising and ...

  17. Marine aluminum vs marine steel for ship hull. What to choose?

    The argument is that it is easier to weld the steel hull of the ship, it is easier to control the process and the likelihood of defect (rejects) is less and we do not need an extra high-speed catamaran and we can (possibly) add 20-25 percent to the mass of the ship hull. But this will entail fuel consumption on an ongoing basis.

  18. Glen-L Marine

    Providing boat Plans & memories Since 1953. For more than 60 years Glen-L has been the world's premier supplier of boat plans and patterns designed for the amatuer builder. We make it even simpler by offering associated supplies and hardware kits for each design. About Us.

  19. Sail Catamaran boats for sale

    Listed hull types include catamaran, monohull, trimaran, displacement and other. Constructed by a wide variety of yacht makers, YachtWorld presently offers a selection of 1,819 catamaran yachts for sale. Among them, 487 are newly built vessels available for purchase, while the remaining 1,332 comprise used and custom yachts listed for sale.

  20. The Mother of All Maritime Links: Page 31 of 47

    All American Marine (Aluminum Teknicraft catamaran work, passenger and pleasure motorboats, Bellingham, Washington) Alwoplast (Builder of large sail/power multihulls, repairs, Valdivia, Chile) AmeraCat Custom Catamarans (Builder of commercial or recreational offshore fishing catamarans, Ft. Pierce, Florida) American Proas, 1898-1998.

  21. 2022 Traxxas M41 Catamaran Base

    Current Traxxas Boats M41 Catamaran. 2022 Traxxas M41 Catamaran Base. Units In Stock: 1. Swipe to View More. Share. Print; Questions? Exterior Colors: ...

  22. Multi-hull boats for sale

    There is also a full selection of trailers for multihull vessels, including aluminum and galvanized steel models that can fit any arrangement and number of hulls. Expert Multi-Hull Reviews ... to 78 feet long, with an average sail area of 1,323 square feet and a maximum sail area of 3,630 square feet. Listed hull types include catamaran ...

  23. Catamaran boats for sale

    There are presently 34 yachts for sale on YachtWorld for Catamaran. This assortment encompasses 14 brand-new vessels and 20 pre-owned yachts, all of which are listed by knowledgeable yacht brokers predominantly in United States, Spain, France, French Polynesia and South Africa. Models currently listed on YachtWorld vary in size and length from ...