Catamaran Aircraft Carrier - why/why not?

Is there a logical engineering reason that no aircraft carrier has ever been built with a catamaran hull - yet? (to my knowledge anyway). At non-technical first thought, it would seem to provide a method for supporting a wider flight deck, on a smaller displacement.

This notion popped into my head while looking at pictures of the real-world side wheel aircraft carriers used for training on Lake Michigan during WW2. If they could be successfully used, why not a catamaran?

Well you're still going to need the same amount of physical space inside the hull, or hulls in this case, to fit all the aircraft, personnel, armaments, supplies and various miscellanea so would it really save you much in the way of displacement? All you would appear to be doing would be lopping off part of the main hull and relocating them to become the outrigger hulls. The two main advantages that I've heard argued for something like this are the ability to create a larger flight deck on the hulls and between them and potentially greater overall resistance to damage if something happens to one of the hulls. I've got no idea of how accurate those claims are though.

http://www.examiner.com.au/story/585487/incats-aircraft-carrier-plans/

Well want an interesting fictional one ?

http://www.combinedfleet.com/furashita/nibai_f.htm

Driftless said:

This notion popped into my head while looking at pictures of the real-world side wheel aircraft carriers used for training on Lake Michigan during WW2. If they could be successfully used, why not a catamaran?

Click to expand...

I suppose it has to do with stability, in calm seas the cat' would be more stable, but facing a side swell the monohull is more stable.

From everything I've heard, it has to do with the lateral torsion of the two hulls against each other in anything other than very calm seas. Unless you're riding perfectly perpendicular to the seas, the hulls will constantly be torquing against each other as first one side, then the other rides over the swells. In smaller, and more flexible boats, structural rigidity can overpower this, or simply ride with it.
But when you start dealing with massive hulls, such as for capital ships, CV's etc, then the stress simply becomes too great, and the ship would literally twist itself apart very quickly.

EDIT...
If Incat claims they can do it, I'd be very interested in learning how.

Well the HSC Normandie Express is 97.2m x 26.6m and has been running for about 15 years now, so presumably a carrier of the same size wouldn't be a massive stretch. For larger vessels a 'floating' (ie, non-rigid) midsection would probably help reduce stresses.

Something a little more in-house. Don't know why.

Cross-deck torsion is a killer, as is the lack of hull volume for accomodation and services. The motion in a seaway is a problem too - catamarans are much jerkier than monohulls, which would make air operations difficult.

That Incat concept would probably be able to operate four F-35s for a day or so. There's nowhere to put the fuel, weapons, or crew for longer. And it could only do it in calm waters.

there is also nowhere to build the ship rember they are much wider than a normal ship so slips will not hold them there are no drydocks for repairs etc. These would have to be built from scratch adding more expences.

You mean apart from Austal USA right? Okay Lake Express wasn't nearly big enough for this sort of job, but they followed it up with Alakai and Huakai, the lengths of which are, respectively, 106m and 114m, plenty big enough, at least for helicopters. You want more hulls, build another yard, and hire more workers, Austal USA would be ecstatic, since it would be them you'd have to turn to for help. In fact, give them a big enough contract and they'll build the yards themselves.

for a while there was a design proposal for the british queen elizabeths, that was a trimaran hull

I can personally tell you, Lake Express can be one hell of a rough ride. One problem with catamarans or SWATH type hulls ls they are very intolerant of the sort of excess weight accumalation that happens to ships. From extra gear squirelled away to the crews old comic books.

wietze said:

for a while there was a design proposal for the british queen elizabeths, that was a trimaran hull

Click to expand...

I also remember this design appearing in British papers in the mid '90s when the RN started talking about a future carrier. I don't know how much the smaller size of the outer hulls compared to the main hull would reduce the torsion and stores problems, but it looked pretty cool

nixonshead said:

I also remember this design appearing in British papers in the mid '90s when the RN started talking about a future carrier. I don't know how much the smaller size of the outer hulls compared to the main hull would reduce the torsion and stores problems, but it looked pretty cool

Click to expand...

Trimarans are fundamental different than cat's; as they're essentially a very narrow monohull, with side floats for stability. Totally different than a true catamaran.

As to the examples cited, they are tiny compared to ships used as carriers. Even a WWII escort carrier (say, the Casablanca Class) is much bigger. For example, the Huakai / USNS Guam cited as an example is only 114 meters compared to the Casablanca's 156 m in length. That's no where near the ~300 meters of a Midway, and positively minuscule compared to even a small modern boat. Say, the (small) 260m Charles de Gaulle, or the 270m Kiev class. That's not even touching the big boats.
When you start talking about more than doubling, or tripling the length, you're going to run into major structural engineering challenges.

But then again, the OP did ask only for an "aircraft carriers"; nothing about the size. So I suppose if you qualify an LPH as an aircraft carrier, then you've met the requirement. And the Huakai/USNS Guam could qualify in that regard... Bit of a stretch to call a few helo's/VTOL aircraft on a boat a proper carrier though.

As to the ride, as was mentioned, catamarans are a much choppier ride. Given they are (by design) intended to float on top of the water, rather than deeply inside the waves, you're going to get a lot more slapping up and down motion. And that's really not good for aviation activities.

How about a Surface Effect Ship carrier - I did have a paper that discussed one that could carry up to 30 aircraft in a double hanger - aircraft couldn't be stored on deck as the speeds that the craft could get up to made it too dangerous, it could launch CTOL aircraft using a ski jump and no cats.

Slightly shorter and not as wide as a CVN IIRC.

Will try and dig the article out.

I think the main limit is that unless the design is really big, there isn't much room for a hangar bay, and thus limit the aircraft capacity. And the savings with a very large catamaran design may not be significant compared to conventional-hulled carrier designs.

PMN1 said:

How about a Surface Effect Ship carrier - I did have a paper that discussed one that could carry up to 30 aircraft in a double hanger - aircraft couldn't be stored on deck as the speeds that the craft could get up to made it too dangerous, it could launch CTOL aircraft using a ski jump and no cats.

Click to expand...

Wait, did someone seriously propose an ekranoplan aircraft carrier?!? Holy carp. I nominate the Soviets to build it, they loved those things. And hey, might as well make it nuclear powered while we're at it - that way we're hitting the trifecta.

Gunnarnz said:

Wait, did someone seriously propose an ekranoplan aircraft carrier?!? Holy carp. I nominate the Soviets to build it, they loved those things. And hey, might as well make it nuclear powered while we're at it - that way we're hitting the trifecta.

Click to expand...

Not an ekranoplan, but a surface effect ship - catamaran side hulls sealed by a flexible skirt and pressurised. The same idea as the Norwegian Skjold class corvettes.

Gunnarnz said:

Wait, did someone seriously propose an ekranoplan aircraft carrier?!? Holy carp. I nominate the Soviets to build it, they loved those things. And hey, might as well make it nuclear powered while we're at it - that way we're hitting the trifecta.

Click to expand...

"The Sovetsky Supreme today achieved miracle of engineering by firing fully loaded aircraft off back of ship with nothing but wind power! Aircraft pilot tragically and heroically died after sinking Capitalist gun-runner attempting to supply deviationist Cossacks."

(On board the Sovestky Supreme)

"Next time, build me a windshield for the aircraft lift. Those strike fighters are expensive."