Broaching wave cat vs fin?

SAWDOC

SAWDOC

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While soaking in my bubble bath reading an old copy of YM, I read an unfortunate tale of a crew on a catamaran delivery trip in the solent hit by a large wave at night ( they thought it might have been ferry wash) - result was that the cat broached and kept going turned turtle and that was that - trip over wait for the RNLI.
Would a fin keeler behave differently in the same situation? ie possibly turn turtle but not stay inverted ( we're not talking Open 60 class - lets assume the keel stays put.) advice from experienced forumites appreciated.
 
The concept of broaching here meaning that they were probably hard on the wind when the wave and forward speed combined to turn the boat side on to the wind. With all sails cleated in hard then the wind could have heeled the cat to the point of no return ie 90 degrees from where it toppled to fully inverted.
Obviously a "lead mine" keel boat will go lot further ie ie 170 degrees before the stability or righting moment is lost. ie at 90 degrees the mass of the keel is providing max righting while the hull shape righting is probably lost.

I think with the cat it is the broach that is very unlikely but it is that possibility of toppling that keeps many sailors preferring the lead mine. Auto releasing sheets may have averted the capsize. Most cat sailors will also reduce sail area much earlier than the keel boat skipper. The thing being the keel boat (lead mine) will tell you in no uncertain terms it is overpowered while the cat just goes faster and faster until.......
All IMHO olewill
 
Lots has been written on this debate and there are lots of factors that contribute to these accidents.

In terms of the keels; it is common practise to raise the centre or dagger boards in big waves so the boat can slide sideways. It works I've done it.

So if the, relatively light, cat is properly set up it will accelerate out of a gust or away from a wave. The mono, with its fixed hull speed and keel, will lay over spilling wind and come up again when the gust has passed.

The problem arises when you are stopped in a cat with the sheets pinned in and the wave or gust arrives. If you can't accelerate away, because of inertia and bad sail shape, and the gust/wave is big enough you will go over.

We are talking wave heights that are, at least, bigger than the beam of the cat. Do you get many 13'6" waves in the Solent?

I think that in the incident you are refering to the crew were experienced mono sailors with no, or very little, multihull experience. I suspect that this was a factor.

Cats and monos are different in many ways - a significant one is that cats are less idiot proof. I speak as one.... who owns a 30' cat and has turned beach cats over.

Paul
 
It was an Iroquois MkII.

Had just been bought for another member of our sailing club and the crew were taking it home. I cannot remember the details but I think the crew were new to cat sailing. Pitch dark at the time of the incident as I recall.

Wayne
 
an iroquois is a narrow beamed cruiser racer type of cat of an old design. in fact from the era when cats were so unstable they used to sometimes fit floats to the masthead. so it was intrinsically vulnerable and with a crew who werent familiar with multis anyway ..........

more modern cats are far more stable with broader beams and usually low aspect ratio keels designed to allow the boat to slide sideways under pressure. from memory stability also goes up with the cube of the length so a cat of 40 ft is twice as resistant to capsize as one of 32 ft all other things being equal.

the key issue though is understanding of the boat. cats show a lot less signs of stress than mono so you cant judge reefing by feel - you have to do it by wind speed and have strict limits you stick to. when its blowy, it also makes sense with a cat to turn into the sort of big bow wave that can be left by (for example) tugs.

I dont know what happened in this case but at an outright guess - narrow beam, dagger boards, boat under pressure, bow wave hitting the side, lack of experience and maybe failure to release the sheets immediately. all risk factors.

basic physics shows that the energy required to flip a cat is several times greater than that required to flip a mono of the same loa. - the difference is that the mono usually comes back upright. whether the mono is damaged and sinking, or whether the cat stays floating ........ well that just gets you into the mono vs cat debate. I've had both, like both and ceratinly never felt at risk in my last cat.
 
IROQUOIS Mk II
Length: 9.29 M / 30.48 Ft
Draft: 1.52 M / 4.99 Ft (board down).
Beam: 4.10 M / 13.45 Ft
Displacement: 3.44 Tonnes
Keel: Centreboard
Berths: 8.

Some of these date back to the early 70's and nothing like more recent cats.

The broach is said to have been in the dark, and most likely most of the crew below resting before their watch started, so possibly no one to leeward ready to let go the main sheet, traveller and head sail. Or as suggested little experience of cat sailing.

The above combination of length, beam and displacement and possible under bridge deck clearance would be found in modern cats.

Having sailed mono hulls for many years I sail a cat and love it dearly for the fact that it's fast, dry, smooth and very stable at rest, not to mention the huge volume and the fact that you have space for all to get away from all if required.

Cats are very different to mono hulls and do take some time to get used to, sail trimming to get into "the groove" is a lot harder and takes longer; getting out of a bad blow also needs more thought. Cats are not for the casual sailor as the hazards are not always obvious. But nothing has the same comforts or versatility in my book; and yes I would never have supported cat sailing years ago, but things and boats do change just like opinions with time and more importantly experience. Oh, and still sail mono's but mostly on deliveries and the odd race.

Avagoodweekend......
 
[ QUOTE ]
an iroquois is a narrow beamed cruiser racer type of cat of an old design. in fact from the era when cats were so unstable they used to sometimes fit floats to the masthead. so it was intrinsically vulnerable and with a crew who werent familiar with multis anyway ..........


[/ QUOTE ]

I think *some* older cats may have been that unstable. I have an older design cat but I am not aware of any Prouts that have ever capsized. Before I brought mine I tried finding evidence of capsizes and could find none. Happy to be corrected if anyone knows different. But then we are no where near as sporty as an Iroquois.

And of course thousands of Prouts produced and multiple circumnavigations completed.

You pays your money you take you choices even with older cats.

Whilst we don't have the beam of modern cats we do have a LAR keel, stout construction and conservative rig.

I have never seen a Prout with masthead float and I am not going to be the first /forums/images/graemlins/laugh.gif
 
As an owner of a MkII Iroquois I feel the need to defend the boat:

Length to beam ratio: Many modern comentators point out that the traditional polynesian LB ratio is Beam overall = half of the waterline length. The Iroquois has these dimensions.

More modern cats that are beamier for a given length are often rigged with more sail. This simply means that they will eventually pitch pole if you push too hard

Prouts are good solid boats - but they are heavy. This costs speed. For some, speed is the point of multihulls. I believe one has gone over - it was being raced somewhere off the IOW.

Keels: LAR keels are a compromise, they are always there to trip over. If you can pull up the centre/dagger boards you reduce this tripping effect. If they aren't big enough to trip you up then you won't go to windward so well.

Masthead float - silly idea, worked though. Most are dispensed with now

I have to repeat the comment above; these boats are not idiot proof. Is this true of any boat with some performance?

I thought long and hard before buying the boat. I was aware of the capsize issues and am of the opinion that they are over represented in the capsize figures because so many were sold to people with no cat experience. The MkI was a very hot boat with a big rig. I think the MkII is a detuned version (because of the capsizes).

Perhaps some pre purchase compulsory blasting about on a hot beachcat would have helped people to understand where the cat needs careful attention. Instead they sold them as safe, fast etc etc

The answer is simple: If its windy make the sails smaller - do not be seduced by the speed!

After having said all that I will probably turn mine over this summer.

I hope you are all now converted - now let that be the end of it!

Paul
 
The only stable attitude for a cat is upside down:-

http://www.youtube.com/watch?v=J9LFsyoUDDQ

I have done this quite a few times on my beach cat. It always seems to be unpredictable.

You are there screaming a long on a broad reach, cat dead upright, stable, both hulls in the water (no fancy stuff) then all of a sudden both bows disappear under the water for no apparent good reason.....
 
[ QUOTE ]
most tend to broach & then do a dymanic capsize

[/ QUOTE ] Would you explain this in longer sentences for us hard of thinking types..

My understanding, is that most cat capsize happens after she buries the lee bow which then stops the boat dead and she has nowhere else to go but over. Otherwise (without daggers) she should slide and oh boy does she slide when I get it wrong. Of course this might be what you are saying, I just don't really understand the language you have used.

For an interesting report I suggest people interested might like to read John Passmore's account of his infamous capsize of a Heavenly Twins, the only reported incidence. I am glad I have never seen weather or seas such as he describes.

Heavenly Twins - Force 12 off Shetland:
 
The early term for this was "a trip around the wire" as the cat stopped and the crew continued on around the fore stay helping the cat to capsize since they were still attached to the mast by their trapeze.

Great fun and even possible on some monohulls but not quite as fast and spectacular.

Avagoodweekend......
 
The Iroquois sits somewhere between a beachcat and a big fat old Prout.

The boat needs to be treated with some respect but I wouldn't normally expect to take a 'trip around the wire.'

P
 
[ QUOTE ]
big fat old Prout.


[/ QUOTE ]

Easy /forums/images/graemlins/blush.gif

But ultimately you are right we all make choices and I know you will leave me standing in any race. We are out and out cruisers so doesn't really bother us - we are probably too busy putting the kettle on !

We are happy, you are happy. And we've all got more hulls than a mono-boat !

Interested in a link/any further info on the Prout capsize you mention. Maybe it was told old to be on tinternet. I know of ones that have lost their rig and even ones that have sunk but don't have any details of any capsize.
 
It was only a few years ago and the owner who sold her used to post here. Have you tried searching on the accident at sea website, I have forgotten where I placed the bookmark right now.
 
I can't find the accident at sea website. I have just spent half my lunch break and can't find a reference (on the net) to a Prout capsize - it actually ends up bringing back this thread !

I am not saying that it didn't happen (although I found plenty of sites on the web claiming that Prouts have never capsize during my search) but maybe it was pre-web.

FYI I did find this link to one of the Iroqouis capsizes for those interested.

It appears to be written by the Skipper. He does mention leaving with Full Main and Genoa on a day when the conditions had been F7/8. Now I wasn't there (well actually I wasn't born!) so can't judge but we wouldn't be leaving harbour with full sail on a day like he describes.

Have a look here

and scroll down or search for the capsize.
 
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