What made modern catamarans possible? The idea was stolen from Pacific islander’s outriggers, as I understand it. The idea seems obvious.
Why weren’t there large, commercial catamarans until the present era?
Catamarans have some disadvantages over monohull ships. Among them is:
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They can’t carry as heavy a load as a comparably sized monohull ship (this also means smaller cabin space).
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They cost more to dock (they take up more room).
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They cost more to build.
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Do not do well in heavy seas.
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Greater susceptibility to broaching and pitchpoling.
I’m going to guess that the main ingredient allowing catamarans is a very strong frame (metal?). The forces on a decent sized hull where it joins the cross-beams- including when the sail lifts one hull out of the water, twisting with wave action, etc. - would be fairly intense. Polynesian outriggers would be on booms tied to the canoe with a bit of give. But, the outrigger if it lifts out of the water is much lighter than half a ship. In the good old days of wood sailing ships, this would require excessive construction, and poor value of weight vs carry capacity for a larger wood cat.
Not really. An outrigger is quite different from a catamaran, but besides that, the Polynesians had actual catamarans before westerners got hold of the idea, so they didn’t need to steal anything from the outrigger design. Besides, Westerners actually got the idea from Tamil sailors in South India, not from Polynesians. It’s possible that those Tamil sailors got the idea from Polynesians, but I’m not sure about that.
No answer to the OP, but when I was a kid in the early ‘70s I really really wanted a Hobie 16. (I had to make due with the 14’ Lidos and Capris at the sailing club.)
Yay, the Hobie 16!! A friend had one that we sailed and raced.
Three cheers for Hobart “Hobie” Alter.
I laughed when I read the wiki on Hobies. “Robust construction” my ass! (OK, there was obviously a flaw or damage to the starboard hull, but still.) There I was…
screaming reach across the lake. I’m trapped out as far as I can go. Wendy has her toes locked in the bungies and has us just skimming the port hull. The next thing I know, the starboard hull folds just forward of the front pylon. The boat came to a dead stop and Newton’s First Law is a bitch.
By commercial catamarans, do you mean high-speed ferries? Or commercially produced sailing boats?
For ferries and cargo, a conventional (single hull) ship has much simpler construction. A wave-piercing catamaran like the Incat can achieve faster speed than comparably sized single-hull ships, but it still takes a lot of power (and fuel) to do so. The Francisco has two 47,000 horsepower gas turbine engines, and can carry 1024 passengers + 150 cars. Compare that to this conventional ferry that carries 1004 passengers + 165 cars, and only 6000 horsepower.
(The catamaran also appears to have 1/10 the tonnage, I’m not sure what that’s about. Is it dry vs. loaded? IIRC these Incat catamarans are aluminum and are much lighter than conventional ships, but still that seems to be too big a difference…)
I’ve never sailed a cat. Except for a homemade cat-rigged dinghy I bought from a neighbor about a decade ago, I haven’t been sailing since I was 15. I still like the idea of a Hobie 16, and I can afford one now (well, I can work it out), but with two destroyed knees I wonder if I can actually sail one?
Sailing can be accomplished in a sitting position, especially if you have two people (a captain and a crew). You could sail solo, but it’s challenging working the mainsail, jib, and rudder.
It’s a lot of fun to push the boat, but that’s where it gets harder on the knees, standing and squatting on the trapeze.
To be fair the Incat goes 58 knots compared to the other ferry’s modest 16.5 knots. That’s where most of that power difference is being used.
That said I have read that catamarans use more fuel although not sure what they are being compared against. I mean, catamaran sailboats are substantially faster than a monohulled sailboat which, in the same wind as a monohulled boat, would suggest it is getting better “gas” mileage (i.e. it is getting more speed from a given energy input hence better mileage, so to speak). Witness the America’s Cup race which all racers now use catamarans (when the Americans were the first to enter a catamaran against all monohulled ships it wasn’t even very close).
I had a Prindle 16. I sailed it on Lake Michigan. Damned lake tried to kill me more than once. Great fun, but not enough sailboat for Lake Michigan when the waves really kick up. I turtled it once, and speared the mast into a sandbar. That was a pain to set right.
I was happy to sell it, after over 30 years of use.
We were sailing my friend’s Hobie 16 on Lake Arthur (Moraine Park) one day. The boat had a new righting system that we were going to practice/play with. We repeatedly raced across the lake, intentionally going over slowly and in a controlled manner, then righting the boat. Rinse & repeat. Over and over.
Our wives were on the beach. People next to them commented, “wow, those guys on the sailboat really suck”.
‘Wow, look at the catamorons!’
There are lots of different tonnages. The figure for the cat is DWT - deadweight - which is cargo carrying capacity. The figure for the conventional ferry is Max Displacement which is the maximum mass of ship and cargo.
Actually I asked the question just after watching this video of a Wildcat 60 in a bit of wind. Well worth your time.
The US Coast Guard has a mono-hull surf boat that does at least as well as that and is probably cheaper to build. I think this is a 47’ boat and if you watch long enough you will see the boat is capsized by a wave and rights itself: https://www.youtube.com/watch?v=aFb3yPtcakc (audio track is loud and annoying so turn down your volume)
Yes. In the video I linked, the chase boat is a self-righting monohull. Still the cat is doing very well. (Looks like fun, but who wants to be so close inshore in weather?)
<Crocodile Dundee>That’s not a pitchpole - this is a pitchpole</Crocodile Dundee>
Lots of different forms of catamaran being talked about.
For recreational/racing sailing boats you could argue that the limitation has been desire and the idea. Modern materials have aided high performance cats, the Americas Cup boats are constructed from little else than carbon fibre and titanium. But off the beach racing cats can and have been constructed from almost entirely wood. Plywood makes for a very string hull and is still used by home builders to create very fast boat. Masts and crossbeams are now usually aluminium or carbon, but the venerable Quickcat (designed in 1957) used wooden crossbeams. They still raced in the 70’s at my club. The Yvonne catamaran (same designer, 1964) used a plywood box section as a cross deck. They still race, although a recent class rule update has allowed them to replace this deck with aluminium beams and add an asymmetric spinnaker.
For ocean-going multihulls materials has been an enabler. There are lots of cruising catamarans out there, some very large ones. And some very quick ones. Once a cat gets large enough you are able to place a cross deck over the two hulls, and now you have a lot of living room, vastly more than an equivalent sized monohull. This makes cats very popular in coastal cruising boats.
But you can’t get away from the problem with a sailing cat that it is very stable when upside-down. A keeled sailing monohull will almost always right itself after a roll-over. A cat won’t. This remains a constant niggle in the back of minds.
You can pitch-pole any sailing boat. But cats are faster, so they tend to do it easier.
Worth mentioning trimarans. Tris have a lot going for them, and you may see that they are the default ultra-performane ocean going sailboat. (Although they possibly are not as fast as a cat, they are a bit safer and easier to cope with.) And efforts towards foiling ocean-going tris are paying dividends. Silly fast. Again enabled by materials and a lot of advanced understanding of hydrodynamics. And money. Lots of money.
But if you get to commercial vessels, it is doubtful you can really claim the idea came from sailcraft. The progression from tunnel hull design seems reasonably clear. And the limitation is going to be materials and construction capabilities to cope with the stresses in what is not an ideal shape. A simple convex hull has lots of advantages. Once you have to join two or three of them the structures become much more difficult and you have to deal with lots of evil stresses. The fast ferries and now the US littoral ships being built by Austal are perhaps the top end of this.
A really important point about long thin hulls is that once your hull is about 10 times longer than its beam (width) it is no longer subject to the usual displacement mode length limit on speed. So multihulls can be fast. There are still complications between the interaction of bow waves between the hulls, but you still get a boat that can be much faster than a monohull for the same length.
The Hobie 16 is the second most popular sailboat design in the world (after the Laser). But it really does show its age. It has little going for it other than its numbers.