Why Do Catamarans Capsize?

[Cat_sailor]

Originally Posted by thinwater

That article is written by a person that appears to have no cat experience.

Interesting comment! Please elaborate!

[Cat_sailor]

Originally Posted by chrisr

article seems to be a fair summary of the facts

but who ever let facts get in the way of a good argument ?

cheers,

I think they probably should from time to time

[Cat_sailor]

Originally Posted by Dave_S

"Im hoping the cruisers forum is different"
Hahahaha, ready, set, go.....

I thought it was a good honest assessment. Other than gear failures I suspect it is mostly human error/exuberance. I've never been in any weather or sea state that was a concern. Although, everytime I have reefed I must have been concerned, so I guess we all have.

I've heard the... "the rigging is designed to fail before the boat tips" ...argument a couple of times. Of course this isn't true for 2 reasons a) the rigging coming down is a life threatening event and no manufacturers are going to purposely design something that is that dangerous and b) if the boat is at 30° on the side of a wave the loads on the rigging required to capsize are probably 1/3rd as that on flat water, how do you design it to fail at the right time in both situations and c) (bonus reason) if it's designed to fail just before capsize on flat water there are no safety margins for when the rigging gets a bit old and tired, so people's rigging would be coming down all the time.

a) isn't that better than flipping over?
b) it isn't constructed to break in every situation?
c) why is that so? That could definitely be a design

[Cat_sailor]

Originally Posted by Rapanui

The article referenced was most ok but only mention 2 mechanisms for capsize, capsize from pitchpoling due to bow diving and lateral capsize due to wave action. I would add lateral capsize due to wind action as probably the biggest contributor to catamaran capsizes, certainly when catamaran beam to length ratios were lower than most modern cats. Many cats have gone over in flat water due to too much sail for the conditions and still do.

The Uk Amateur Yacht Research Society was active in developing multis in the 1950-1980s and carried out a lot of research into capsizes and their causes and published a book Multihull Capsizing a pretty in depth study of the subject. Still a good read.

I owned a Sailcraft Iroquois 30 for over 10years, which featured prominently in said book, with a history of capsize. With a large sail area, a 180% genoa, narrow beam and fine bows, all 3 mechanisms were triggered by various owners. However, it could be and was usually sailed safely due to seamanship and caution, and one even circumnavigated. Sailing too fast downwind in high seas, with large beams seas or with too much sail will be a risk in all craft. Racers take the risk and hopefully equip themselves as well as they can, cruisers have to rely on sense, caution and seamanship.

That's actually a very useful information! Thanks for taking the time to add value to the discussion! I thought wind was in the article but i might be mistaken!

[Cat_sailor]

Originally Posted by jmschmidt

Forget the scientific explanation. Sailing cats flip when on a reach in a blow and they come down off a wave at a certain angle (which may vary with hull design), bury the lee bow and the helms-person fails to dump the main sheet instantly.

Adding to this danger is the latest penchant for today's builders to lead all lines, including sheets, halyards and whatever, to a bunch of clutches and a single winch at the helm station. In a split second the boat will, at best, do an un-commanded jib or at worst, bury a hull and go over. If I were sailing one of these on the open ocean I would wear a machete on my hip to chop free all the lines at once to hopefully release the pressure on the sails.

Now, after burying a hull, if you have the misfortune to be on one of those new cats with the so-called "forward cockpit" designed to please the ladies, standby to have this giant open pit on the foredeck fill with a couple hundred gallons of water further enhancing the boat's instability.

Why would you exclude a scientific explanation? Otherwise it is just ungrounded thoughts?

[Cat_sailor]

Originally Posted by Bullshooter

That article the OP linked was in bad need of an editor. The subject matter discussion seemed logical, but the frequent misspelling and poor grammar seemed to dilute its credibility for me.

"Large waves are always a factor con safety at sea; "

"If the boat speed is still too high, the next option is to deploy a drogue that will break the boat and add some directional stability." Etc.

Or maybe I am being pedantic...

I definitely agree with that. Good grammar adds credibility!

[Dave_S]

Originally Posted by Cat_sailor

a) isn't that better than flipping over? The courts would answer that very question for you. So from the manufacturers point of view, in the event of the rig failing and a person on board is killed, in court when the manufacturer and the designer and the CEO ARE being tied for manslaughter the arguments would be that maybe the boat wouldn't have flipped, and the rigging has failed prematurely or there is no assurance that someone or that same person would have died had the boat capsized. They would probably argue that the deceased person was on deck and would have been thrown clear in a capsize and therefore would have survived, as such the design feature was entirely responsible for the death of their client.
b) it isn't constructed to break in every situation? It's not DESIGNED to break in any situation. It's designed not to exceed it's SWL in all reasonable situations when reasonably maintained.
c) why is that so? That could definitely be a design. It could be designed that way but it is not. If you were to design the rig to fail at a predetermined stress level you would design a specific way in which the rig would collapse. To do that you would produce a rig that was significantly over specification so you could control where and how it failed with sacrificial points on the rig in a number of critical places around the rigging so it would collapse in the most benificial way. You would attach some device's to capture or slow the speed of the rigging as it wipps around the boat when released like a spring. The end result would be overweight expensive rigging with these fuses/sacrificial points around. I have never seen such a device on any boat. I'm sure someone somewhere has tried it and tried to sell it as a feature but is a crazy idea.

I don't know why some words aren't blue, I didn't do it to highlight them.

[Montanan]

Because catamarans are not Webos!

[argonauta1]

I'm a keelboat circumnavigator. Seen a few cats out there but as we know, the cat is inherently less stable in serious weather. I have no credibility therefore as a cat driver but of the dismast cases I was aware of, they were all cats. No capsize just rig loss. Of course, we all know why a cat has a flotation bag at the mast head and a trap door in the hull. No trap door, better carry an axe but at least a cat will float inverted. There are many good accounts out there on this attribute of a cat. On the other hand, my wife would have preferred a cat for the larger living space. Safety at sea; I'll stick with my first choice.

[sail4evr]

20ft+ beam breaking seas for which rhere are sea anchors and drogues to keep your bow or stern to the oncoming seas

[170122]

All I can say is I navigated on a nono hulls many years, heavy seas they are there to stay..
Experts on Cat multi-hull Can handle those vessels to do extraordinary moves and speeds, now the real vision is hydrofoils going faster than most power boats, the adrenalin and sport is overwhelming but is not for me..

[Talbot]

Why do cats capsize:

It is really simple they are being sailed in adverse sea conditions with too much sail up and not enough crew to be able to respond. You can't race a cat without risk - especially if you are short crewed.

They are more likely to pitchpole.

basically a cat will accelerate much faster than a mono, if you are going downhill and get to the top of a wave, suddenly the sails are getting the full wind speed, and gravity is assisting a sudden speed increase such that the bows bury on the back of the next wave.

I sailed a catalac for many years, and whilst undoubtedly the slowest boat to windward, their hull form allowed a great speed ability in the right conditions. Nobody has capsized a catalac (unmodified) but I do know of one 9m that pitchpoled.

The solution - sailing is serious, don't be unseamanlike. sail within your boat and your own capabilities.

[aqfishing]

Originally Posted by thinwater

That article is written by a person that appears to have no cat experience.

I must day I tend to agree with you. A study of a study.

The author is merely conveying what most people know, except with a bunch of fancy words.

I feel that was a total waste of time reading.

[Piratenorm]

We chartered a crewed Lagoon 45 years ago around St. Vincent and the Grenadines from Fiesta Yachts. The skipper used to deliver Leopards from South America. He looked a proper old salt. Mid-way thru the week he and his wife became glum and downright teary after receiving a phone call. I asked what had happened and he said one of their friends, delivering a Lagoon 45 from France, similar to theirs had pitch-poled crossing the Atlantic. Two mates lived, the skipper, high in the top helm position, died.

I asked how that happened and he said the delivery crew was late on a deadline delivery to Fiesta and was flying too much sail for the conditions, surfed down a wave, dug in the bows and the wind did the rest.

Sad day that day.

[aqfishing]

Originally Posted by redneckrob

Sorry but I'm not getting what you see as the benefit of the alternative to leading all the lines to one place in the situation you describe? Is it better to have to run all around the cockpit and to the mast to release sheets and halyards when you have to do it in a hurry. Are you advocating for hand tending the main sheet while you cruise? What's a better setup, in your experience, on a cruising cat?

Ah, nicely put. Thats just his problem, clearly no cruising cat experience.