10 Ways to Use a Catamaran

[@thematronsmilitia]

I appreciate this video. I've been daydreaming about building a sailing catamaran for chartering pacific crossings or as a packetship/light freighter. But I live really far from an ocean and there's lots of neat things I could do with a motor-cat on the closer lakes or rivers without running up a wild fuel bill

[@nordfresse]

Why is it tho that we are still not seeing any big catamaran cruise ships?

[@crasch4]

Thanks for the videos! What are your thoughts on SWATH / SWASH ships? Ramform vessels?

[@DatawaveMarineSolutions]

I actually worked at a firm that did some of the major commercial SWATH designs in the 1960's. My main thought is that all three of those vessels are specialized applications. SWATH vessels are great for seakeeping. That has wonderful applications for passenger transport. I saw great applications there for pilot boats. The main problem is that for smaller boats, you need active ride control. Otherwise, the waves slam against the underside of the crossdeck and quickly fatigue the crossdeck. Active ride control is expensive, often needs control system tuning, and is not popular with owners that have small budgets. So I would only suggest SWATHS for large ships. They work great in those cases. Look at the US Navy T-AGOS ships en.wikipedia.org/wiki/USNS_Impeccable_(T-AGOS-23) The SWASH concept seems to have a lot of potential for smaller vessels. I assume you mean something like this: www.bluebird-electric.net/SWASH_Small_Waterplane_Area_Single_Hull.htm I think with the right hull placement, this SWASH concept could possibly eliminate the need for active ride control on smaller vessels. That sounds great. But again, I would see that as a specialized application for cases where seakeeping is especially important. Both the SWATH and SWASH concepts sacrifice quite a lot in deadweight capacity. They can't carry much weight, but the passengers they do carry will get the best ride. Ramform vessels. I assume you mean hulls like the Ramform Titan. www.marinetraffic.com/en/ais/details/ships/shipid:372038/mmsi:311000084/imo:9629885/vessel:RAMFORM_TITAN I think this is highly specialized and only useful for Oil and Gas seismic survey vessels. From a resistance perspective, they are terrible fuel guzzlers. As I understand it, the entire purpose of the hullform is to minimize motion at the stern, where all the seismic streamers attach. Minimizing the motion improves the quality of their sensor data. I can't imagine using it on any other application, but it works great at what it does. What is your favorite hullform, and why?

[@crasch4]

Many thanks for the detailed response! Yes, your assumptions are correct. I'm especially interested in seakeeping ability because I'm interested in seasteading: www.seasteading.org. i.e. residential structures that can survive indefinitely at sea. Therefore, cost, spaciousness, comfort, and seakeeping are the most important criteria for me. Fuel consumption is not as important. I don't really have a favorite hull design yet--I'm still exploring designs. Here's a few I like though: Stability Yachts: www.stabilityyachts.com/ They have a dynamic ballast system, so they can switch from catamaran to SWATH mode, depending on whether they're in movement or not. They're designed to be operated by people who are handicapped/wheelchair bound, so everything is on one level. The interior is designed to be pressure washed, and the there's a swim lift that makes crew transfer easy and safer. I also like the design of the M/V Susitna, which also has a variable ballast system so that it can float in a mere 4 ft of water: gcaptain.com/infamous-mv-susitna-finally-put-to-use-with-philippine-red-cross/ Although they haven't built it yet, I think the Hermes WHY is beautiful, and has oceans of space: www.sspa.se/ship-design-hydrodynamics/when-hermes-met-Wally www.solaripedia.com/13/200/2029/why_solar_yacht_full_scale_model.html However, I don't have a good intuition for how the hullform results in better seakeeping ability. All of the above ships meet the design requirements for indefinite operation in a protected bay. However, they're all pricey. So I've been playing around with ideas to reduce the cost (or spread it out). You can see some of my (amateur) designs for "baysteads" intended for protected waters here: The Juggernaut SWATH: 3dwarehouse.sketchup.com/model/56d9456c-21c4-42ba-afa1-8e6cf00701bb/The-Juggernaut-a-variable-draft-small-water-plane-area-pre-cast-modular-trimaran The Flying Saucer Houseboat: 3dwarehouse.sketchup.com/model/e575b6d2-3cf5-4395-a828-f03cb078a8fe/Flying-saucer-houseboat For open ocean conditions, I think something like the FLIP ship would be necessary for comfortable and safe for indefinite deployment: en.wikipedia.org/wiki/RP_FLIP The Red Hawk cellular spar is also intriguing: www.offshore-mag.com/articles/print/volume-75/issue-4/engineering-construction-installation/red-hawk-stands-as-first-spar-ever-decommissioned-in-gom-p1.html The pneumatically stabilized platform (PSP) could offer a pathway to a platform that is economical enough for residential use: floatinc.com/PSPTechnology.aspx Both spar and PSP could be used with oscillating wave energy generators (OWC) to provide energy for the platform: en.openei.org/wiki/Wave_Energy Thanks again for sharing your thoughts!

[@crasch4]

I replied before, but it seems to have disappeared. Sorry if this is a dupe! I don't really have a favorite hullform--I'm still learning about the many different kinds. I'm interested in stable hullforms because I'm interested in seasteading (i.e. building ocean based cities) www.seasteading.org For my purposes, stability, comfort, and capital cost are the most important considerations. Fuel costs aren't as important, since seasteads will likely anchored in place most of the time. Although I don't have a favorite, I like the following ships: Stability yacht www.stabilityyachts.com/ I like this one because it's designed for use by people confined to a wheelchair. So all of the systems are on one level, the interior is designed to be pressure-washed, and there's a powered swim lift to make it easy for crew transfer. It also has a variable draft. M/V Susitna vigor.net/projects/project/m_v_susitna This one also has a variable draft (can operate in as little as 4 ft of water), and a huge lifting platform: Hermes Why: www.designboom.com/design/why-wally-hermes-yachts/ This is the one that got me interested in the Ramform design. It's incredibly spacious, and apparently will be quite stable. (Note, although a fullscale model has been built, it's not yet been produced in full.) The above are designs that might work in protected waters. Below are designs that might work for open ocean conditions: FLIP ship en.wikipedia.org/wiki/RP_FLIP This one might work in the open ocean--it dampens wave motion by a factor of 10 (i.e. a 30 foot wave feels like a 3 foot wave). Red Hawk cellular spar www.offshore-mag.com/articles/print/volume-75/issue-4/engineering-construction-installation/red-hawk-stands-as-first-spar-ever-decommissioned-in-gom-p1.html A tension leg oil platform built out of seven 20 foot diameter hulls. Due to the smaller diameter hulls, it can be produced at a much lower cost than most spars. Float, Inc. pneumatically stabilized platform floatinc.com/PSPTechnology.aspx oceanenergy.ie/platform/ Open bottomed, modular platform that can combined with oscillating wave power generation technology to both produce power and dampen wave energy. Unfortunately, the founder is elderly, and the company seems to have paused operation. If you're interested, I've made a couple of (amateur) models of "baysteads" intended to be long term anchor outs in the San Francisco bay: Juggernaut: 3dwarehouse.sketchup.com/model/56d9456c-21c4-42ba-afa1-8e6cf00701bb/The-Juggernaut-SWATH-a-variable-draft-pre-cast-modular-extreme-houseboat Flying Saucer 3dwarehouse.sketchup.com/model/e575b6d2-3cf5-4395-a828-f03cb078a8fe/Flying-saucer-houseboat If you were to design a residential seastead, designed for indefinite anchoring in the SF Bay, which hullform would you choose?

[@DatawaveMarineSolutions]

Nice link to seasteading. For seasteading, you are in a completely different type of ship. I would go with variations on traditional monohulls. When you get to the size of a floating city, the shear mass of the vessel means that it will have very little response to waves. And it does take a lot of machinery to support a human city. Take cruise ships for example. All the people are housed above the main deck, partly because everything below main deck is full of heavy life support machinery. For seasteading, I think you would want a platform similar to an FPSO (en.wikipedia.org/wiki/Floating_production_storage_and_offloading), of course, without the oil and gas machinery. I would also consider concrete construction. Steel has a limited lifespan. Concrete can last a lot longer, if properly designed, which reduces the lifetime cost of the ship. The main downside of concrete is the weight, but that is actually an advantage for a seasteading application.

[@crasch4]

Thanks for your thoughts! I agree that concrete is the way to go for the hull (with fiberglass/basalt mesh for reinforcement). I also agree that something like FPSO's might be the way to go once you reach a city sized structure. However, I think one needs to go through some intermediate steps before they are practical financially. For example, the Girassol FPSO, now operating off Angola, cost $756 million. The hull alone is over a $150 million. Cruise ships are city sized as well, but they too cost in the $700+ million range. IMHO, investors will only be willing to put $500+ million in a FPSO / cruise ship sized vessel once the business model has been proven with smaller vessels. Blueseed, for example, was a seasteading startup that planned to retrofit a used cruise ship into a floating, visa-free tech hub, and place it 14 miles off the coast of San Francisco. However, although they were able to demonstrate significant demand for berths once the project was completed, they were not able to raise the $30 million to complete the project. Max Marty, one of Blueseed's co-founders, discusses some of the issues they ran into here: kzbin.info/www/bejne/p4DCg5qKna2qm9E&app=desktop Therefore, although the FPSO/cruise ships are proof that the technical challenges can be solved, I think one needs to start with a much smaller, less costly vessel to prove out the demand/business model first. Which is why I'm interested in building single family "extreme houseboats" for the San Francisco bay.

[@superdepronic]

Aircraft carriers ?

[@DatawaveMarineSolutions]

For aircraft carriers, I have to defer to someone with a better knowledge of naval strategy. I see that the aircraft carrier has two issues that drive them to monohulls. First, most aircraft carriers are heavily armored to protect from torpedoes. Armor weighs a LOT. Several hundred kilograms per square meter. To support all that armor, you need the large displacement of a monohull. The second issue is the deck area to land aircraft. First, you need a LONG deck. That makes for a long ship. In those cases, the thin cross deck of a catamaran runs into problems providing the strength to support such a long length. So for a long ship, a monohull is again more appropriate. An alternative: helicopter carriers may be a strong candidate for catamarans. They don't necessarily need long decks. And large deck area would allow you to launch multiple helicopters at the same time.

[@ravenwing199]

Carriers need a large area for their massive MASSIVE workshops fuel bunkers and Hangars. Unless you can make a 600 ft long 4 story cat Superstructure they will keep the Carriers as Monohulled Ladies.

[@KuraIthys]

Yeah, leaving aside other considerations, the primary requirement of a carrier is runway length. And fundamentally a runway is a long, thin structure. Indeed, at some point the runway on many carriers was made diagonal, to maximise the linear length of it. I don't think catamarans are optimal for that. On a side note, carriers are a nightmare from my perspective as a civilian pilot... Oh sure, I could land my small 2 seater tecnam on a carrier deck no problem. The groundroll is 35-70 metres if you're competent. But even for GA, a typical runway is at least 1000 metres/000 feet, if not quite a bit longer than that... (3250 feet) It'll be a LOOONG time indeed before it's plausible to build a runway on a boat that isn't using special adaptations and purpose-built aircraft to perform operations... I don't see a 1000 metre long GA standard runway on a ship any time soon, do you? XD Much less the 3-4 km long structure required to support mainstream airliners... hmmh. The 5 km long cruise ship with it's own runway... Sounds fun. ;p

[@quillmaurer6563]

Probably the best use for a catamaran, for which they're quite popular, that wasn't mentioned here, is a case in which there is a large sideways force applied high above the deck: sailboats. Catamaran or trimaran sailboats perform way better than monohulls, and have a lot of other advantages as well. Honestly I don't know why anyone even builds sailing monohulls anymore.

[@blackrabbit212]

1:40 Why would a catamaran reduce fuel consumption?

[@goawaygoawaynow]

A catamaran with the same stability as a monohull will have much less wetted area and frontal area with its two slender hulls. That assumes, of course, that the stability is the main concern and weight carrying is secondary.

[@blackrabbit212]

@@goawaygoawaynow Thanks, goaway. I hadn't thought in terms of hull cross-section, but that makes sense. I shall goawaynow.

[@sealpiercing8476]

@@blackrabbit212 Also, usually if you split a monohull's displacement between two cat hulls, each of them has less than half the wave-making resistance because the length to beam ratio is higher. For most (almost all?) ships this means less drag.

[@blackrabbit212]

@@sealpiercing8476 Thanks for that. I had obviously forgotten the ratio and it's effect on drag. What a silly rabbit!

[@WolfKenneth]

Cats are great cruising yachts that main deck gives great common area, two huls give place for cabins, great stability for live abord conditions. But they are also good for fast yachts that use hydrofoils. I'm wondering if one could combine that, because cruising cats while are comfy and not slouch but aren't speed demons.

[@quillmaurer6563]

I assume you're thinking of sailing yachts - indeed catamarans are great for a comfortable, spacious but decently fast vessel. I once sailed aboard a 57' catamaran, the Shearwater, that had served both the "speed" and "comfort" roles with different owners, showing how well suited it was for both. First owner, the one who commissioned the build (a one-off vessel), was focused on speed. He had it built as light as possible and minimized onboard equipment. Heard he got 22 knots out of it, which is blazing for a non-racing sailboat. It was later sold to a quirky old musician who turned it into a charter vessel. He loaded it down with a lot more equipment (galley, desalinization, generator, etc) and didn't want to push her as hard for fear of damaging it, as it was now his livelihood. During my trip saw 11 knots, which is still decent, but the vessel was very comfortable and spacious. Had 15 people living aboard for a week (college student cattle), and for the most part we were in relative comfort. Decent seakeeping, though a few of the people got sick on 3' seas. Given my experience with that and all my sailing knowledge, I don't know why anyone would ever want a monohull sailboat except maybe for plaining-hull skiffs (Sunfish, Lasers, etc), the only question would be catamaran or trimaran, each has it's pros and cons - personally I'd probably go for a trimaran if I were to ever have a sailing yacht.

[@0o0o099999]

Doesn't tug boats need to have a large wet area to resist sideways drift, like a sailboat? I thought that was why they have so big draught.

[@DatawaveMarineSolutions]

For harbor tugs, yes. When guiding a large ship into port, they put the tug sideways and use that large area as a massive sea anchor. But other types of tugs don't need that. Some tugs are just used for straight pulling of barges out at sea. Those are the types that may benefit from a catamaran.

[@0o0o099999]

Thanks for answer and interesting video :)

[@Femmpaws]

I did a design for a fish packer for Alaskan waters that was a cat. Loaded speed would have been about the same as the power barges that are in use. The empty speed would have been about 30 to 40% faster on like power.

[@jamesjograce]

why don't large cruise ships companies use twin hull? what is the size limit?

[@DatawaveMarineSolutions]

There was one instance of a catamaran: the Radisson Diamond. (www.castlesoftheseas.nl/radisson-diamond.html) This vessel was a SWATH, which I consider a subset of catamarans. Catamarans for cruise ships is something I wanted to explore more. But here are four explanations that I would expect: 1.) Cruise ship owners relentlessly design their ships to maximize suites with exterior balconies. That is what sells tickets. A catamaran adds extra interior space without any extra balconies. 2.) Cruise ships need to support an entire city of people. That requires a lot of machinery. Typically this gets stored in the hull, below waterline. You probably can't fit all that in with a catamaran. 3.) Simple bias. Catamarans are typically considered fast and light. Not capable of supporting large weights. 4.) Concerns over stability. A monohull can typically heel to 40 - 65 deg and remain stable. This allows plenty of reserve energy to resist capsizing. Catamarans are much stiffer. They can't heel that far, but it does take a great deal more force to heel even over to 10 deg. And some stability regulations actually require heeling over to the 40 deg mark as a reserve safety. But I scanned through the USCG rules, and I don't believe those heeling requirements would apply to a large cruise ship. So I think stability would be another perception issue. Summary: Why not use catamarans on cruise ships? I can't think of any show stoppers. And larger cruise ships are now trying to fill the ship with equivalents of amusement parks. So they may switch to catamarans and use the large interior space for onboard attractions.

[@Dave_Sisson]

Two companies build high speed cat ferries, Incat and Austal. Both have built them up to 11,000 gross tons and 110 metres. Incat has released designs for larger ships on their website, but while they have a full order book for 110 metre vessels (3 are being built currently at their shipyard in Hobart), there has been no interest in anything larger.

[@quillmaurer6563]

One thing I can imagine is that they probably are limited by harbor, port, draft, and height limitations. These limit the maximum dimensions of the entire ship - beam, height, draft, and length. Modern cruise ships look really blocky because they want to fill these dimensions as much as possible. As they are, they need to have a good bit of volume below the water given their weight (much of which comes from height, they're much taller than they are wide), so limited to these dimensions this would be like cutting the middle out and making the now two hulls deeper, which would probably be less stable and have deeper draft (which is probably limited). The main advantage of a catamaran is making the vessel wider for the same displacement, which wouldn't work for a big cruise ship as they're already at their width limitation with a monohull.

[@KuraIthys]

Incat built the devilcat, which is certainly the largest catamaran I've personally ever seen. Certainly interesting that Australia is so prominent in the building of large catamarans... They're very common as short range city harbour and river ferries around these parts... The devilcat made me really nauseous though, where I can't ever really say I've been seasick on any other kind of ship. I'm sure that's something that can be improved upon, but it's not a great look for a passenger service...

[@tommyb6611]

even to shis day i am stunned they are still pushing for those gargantuan mono hull cruise ships instead of catamaran style which could expand into sooo many activities...imagine from the missle section under it, all kind of water sports that can be done

[@DatawaveMarineSolutions]

There is definitely an argument for a multi-hull style cruise ship. I have limited experience working with the cruise industry, but that experience did suggest two reasons for the conventional monohull: 1.) They need a lot of space and a lot of buoyancy to include all the support machinery below deck. Everything from HVAC, to drinking water, sewer, power, industrial galley, garbage disposal, ... It takes a lot of industry to support a minature city. 2.) The second reason is marketing and branding. They work very hard to ensure all the ships in a brand have the same "look" to them. Something like a catamaran would require a whole new brand of cruise ships. The argument still has merit. But I think it comes down to economics. For a cruise company to really succeed with a catamaran, they would need to start a new company / brand of cruise ships. That's a major gamble.

[@tommyb6611]

@@DatawaveMarineSolutions You hit the nail in the head with the economics. All they want is profits, more of them. And that is where dual hull shines. On top of that, you can house more equipment and reduce the foot print of the ship for the same number of people. If i remember correctly a super cruise ship has like 1000 crew to 4-5000 guests. With dual hull, you can create accommodations for guests lower and for the crew to have them in the middle section facing inside. This was you cut down in the decks needed. The marketing brand loyalty is not valid. Ships today are different one from the other and in fact marketing people try to make unique rides and promote them to get out of the norm, so you saying they try to be similar is not just wrong, is the opposite. People flock to the cheapest and most entertaining cruise, not giving much crap about the company. Now, the cruise ship, can use the wide decks to create most luxurious penthouse type accommodations for those willing to have a huge comfortable room...or create a new class, of larger rooms than the generic cramped ones for those willing to pay a bit extra. With the wide decks they can make those carousels even bigger and better because the base now is very stable and not prone to balance issues. And again, for the company it will be cheaper to run because catamaran is more economical.

[@FITA-369]

👌👌👌

[@russellrattys6581]

Hi, i have been watching whale wars because youtube suggested one of their videos, and i have noticed a few occasions where either a catamaran or a swath ship would come in really handy, ok, so from the outset, they got what they could get, but when they commissioned a new ship, and it was a mono hull, i was a little surprised Say if they used a swath ship, they could have a large helicopter pad on the deck, with a large hangar to roll the helicopter into They could have an underslung launch ramp for the rib's they use, surely launching a rib from a ramp, underneath a large ship would be slightly more covert, also, the big ship would keep the smaller boat safe from the wind and waves during launch Another ideal is, they carry a lot of crew which arent always used to being aboard a ship, the swath would free a lot of symptoms of seasickness would it not? Again, i saw some of their ships being rammed by other ships, their ships were rising out of the water and hammering back down, a swath would be more stable wouldnt it? There's many more instances where i saw a larger deck would be an advantage, but i dont wish to bore you, im sure you have seen the episodes and conducted your own theorys about their ships However, i will ask you this, as you may want to make a video on it... If the crew of whale wars approached you as a ship designer, and asked you to design THE perfect ship for their job, with no bounds, basically what you design is the final design, what would said ship look like? Heres the specifications they require from what i have seen 1 they need to cover great distances at high speed to get to the locations in the first place 2 the ship has to be stable enough for non seafaring crewmembers not to become ill 3 they have to store and launch a helicopter from the upper deck 4 they have to launch small boats from the main ship at sea 5 the ship has to combat ice fields in the sea without taking significant damage 6 the ship has to cope with damage from being rammed from other vessels 7 the ship has to be very manoeuvrable 8 the ship has to be as economical as possible to run and maintain If you can think of anything else from watching the episodes of whale wars, add those issues/sollutions Hope to see a video about this one day, keep up the good work, the videos are very interesting, and if i won the lotto jackpot, od definitely approach you for the design of a small ship for personal use

[@abidjan63]

Your nº10 is more a prao / proa than a catamaran I reckon, with assymetric hulls.

[@ek9772]

I very much appreciate your lessons. These are subjects seldom discussed, and yet of they are of great importance. I am still on the sidelines regarding my understanding. From what I understood a trimaran is more stable (almost unsinkable) than a catamaran. But it would appear (to me at least) that these boats are used less than catamarans. Why?

[@DatawaveMarineSolutions]

Generally less experience with trimaran designs. I argue that trimarans work best in a small niche between catamarans and monohulls. They have less cases where they are the perfect hull for the job. But still definitely an important hull type. I did a video on trimarans if you want to learn more about them. kzbin.info/www/bejne/fJu1hJqLopVmqs0

[@KuraIthys]

I've been on a catamaran ocean-going ferry. Wasn't a pleasant experience (like more than 10% of passengers had severe nausea). But, it was an interesting ship, and 900 passengers + 240 vehicles is nothing to sneeze at. Also it's interior space was very wide. Easily as wide as ferries I've been on that were about 3 times as long as the catamaran was... However, that nausea problem is a bit nasty for passenger service. And this particular vessel only lasted about 2 years in passenger service on that route. (though it apparently still carries passengers in a different country now) On the other hand, this same country has a truly staggering amount of catamarans in use as ferries on rivers and bays where the water is calmer. They make pretty good ferries overall, as long as you can counter-act the high nausea factor...

[@janus737]

Please note, fishes in a net are not the dead weight.

[@ivanlaracuente6234]

Love your designs! I have a patent on an ocean wave generator but one of my first early designs is applicable to large container ships which can reduce fuel consumption by about 75%.

[@KuraIthys]

I don't have the money to build even a small ship, but I'd love to build an electric/solar powered ship... A catamaran seems like a good base for that. Solar power is dictated by surface area available for mounting solar panels. Thus what you want above all else is the highest possible amount of deck area (or really, roof area) for the lowest total mass of vehicle... And ideally as little resistance as possible. Ships are rarely fast enough to worry about air resistance, so it's entirely the hydrodynamic resistance that dominates... This is a concept akin to a sailing boat, but with less complex restrictions; When the sun is out, you can move. When it isn't, you can't. (well, batteries somewhat negate that second point, but overall that's still accurate...)

[@DatawaveMarineSolutions]

I actually did some work for a client that applied that very idea to build solar powered yachts, made from catamarans. (www.novaluxeyachts.com). The concept works.

[@danr5105]

I point out where the catamaran seems to fail. You want your vessel to flex during storm seas. The catamaran does not have good length wise flexibility, the section joining the two hulls needs to be too stiff to give this desired flexibility in the hulls. Sure catamarans can still float in a rough sea but the boat is being subjected to loads that make it want to come apart rather than rolling with the punches from a stormy sea.

[@carlechevarria2226]

I went from Harwich England to Holland with my car on a cat and the smoothest ride ever. Actually there was no sensation moving

[@omarblackman7208]

I don't need a clearance in a channel

[@jamesmerkel9442]

the only exception is boomer class ugly hang over from cold devil script war, but to b safe it needs to transit to polar hiding ground above water in peace time. Below ice is only place u hve to drive a sub, can't b on the surface.

[@jamesmerkel9442]

We r not playing any reindeer games any more it is over light won humanity won & evil won't b tolerated. If u don't want your sub marked pinker or pressure mine attached u better drive on the surface bc it is peace time except for open season on subs. Building or selling or giving subs tech is not allow don't waste humanities resources any long w/red vs blue game is chinese checkers every 1 against every1 or any war script or lite beer false game. When u still or waste humanities resources u r stealing from ME/God & from GOD7 Kingdom & ppl. It is not your money or nor r u allowed to decide any spending. Only ppl glorified in Christ Or hving authority appointed by Me or SON allowed to rule or stand in as earthly judge.

[@Al828282]

NO! Catamarans are NOT the solution! For starters: dock space. Second, catamarans are far from ideal when you consider the layout of mechanical and engine rooms.

[@Milesobrian]

Aircraft carriers?