Multihull Capsize Prevention <split>

Yes Angelique,

I was referring to Richard woods as he has been in storm conditions. In some thing (possibly someones posting) in the last fortnight or so I read a article on Richard woods and his boat he had abandoned. The winds were mentioned as being 55 knots by the helicopter pilot and height movement I think was 20 feet. the boat was Eclipse (Design name or boat name?)

He tried a parachute anchor in moderate condition before hand and found the motion to be a lot more extreme in the storm, at the end he found it help to stream it off just one transom to be the easiest on the boat. Using the diagonal length to help.

in terms of Richard abandoning ship was it also a case of not knowing how much longer it would last or was it abating at that point.

The boat was found later on still upright.

 

In terms of the book Catamarans the complete guide to cruising sailors I mentioned earlier.

I have just got out out from the library to refresh my memory. It has a chapter on just about every thing It cover virtually all aspects from differences between catamarans and mono hulls, in handling to seamanship as well critical issues and design considerations.

 

I posted before that through the duration of the event the seas can change considerably. The sea state depends on many factors both historical and current and no single tactic will work in every situation. Sometimes it's just a try it and see approach, sometimes the tactic is abandoned (usually along with the drogue) because it turns out to be more dangerous for some reason once it's deployed. Because that particular vessel has a different design and different dynamic response.

I don't think a lot of sailors really appreciate the difficulties making a call on what to do and when to do it in a real survival situation. The heavy weather experience of a well crewed racer is also of little use to a short handed crew on a cruising boat.

Many books on multihull tactics will simply be reporting the current best suggested practice, which tactics work and which don't are tested to the point of failure and reported by reasearch establishments, principally Wolfston. Designers simply pass on this information, I don't know of any that conducted wave tank experiments themselves. Only towing tests.

Once people realise they have no control any more and they are in a dangerous situation they are best advised to ask for rescue. It's more sensible that trusting to providence and hoping they will survive an inversion on a catamaran which in heavy seas is a very dangerous situation.

Because the cat was upright afterwards doesn't mean there wasn't a high risk at the point in the storm where the skipper chose to ask for rescue.

In this sport an experienced hand is usually someone who weathered one event and maybe found a good tactic for their particular vessel. If you can seek someone with such experience with a similar design and ask them what worked. Sometimes this information has filtered back to the designer who may or may not want to publish it.

 

The idea I had with mentioning the books was to provide possibly more option to try before you needed them. If you don't know of them you cant try them.

As to Richard Woods abandoning ship none us where there so we can't comment on exactly what the conditions were like only make asumptions. As I mentioned was it abating or not at that point we don't know.

 

Corley mentioned a book by Gavin LeSuer, Multihull seamanship, that book was put together with experinces of other sailors and Lock Crowther willing to pass on their knowledge. boats ranged from 71 feet to 31 foot.

May be the problem is that mono hull sailors are not use to sharing experience, as I have seen with multihull sailors/designer.

for a bit of balance.

How come there are so many mono hulls losing their keels lately 2 or 3 open 60s have finished the Vendee globe with out a keel relying on water ballast. Fixed and pivoting.
How about the ones in the southern ocean rescued by the Australian navy.

 

It's interesting that extreme offshore monohull race boats are becoming less seaworthy in pursuit of speed. As they get faster they are having to confront structural problems that have already come to light for multihull designers. The MOD70 one design for example was a way of taming the ocean racing ORMA60 trimarans back to a point of safety over performance (crewed only as well). I'd not be surprised if the VO70's go one design sooner or later for similar reasons. It's about value for sponsors dollars too if you want more than one cashed up player with everyone else being an also ran you have to start putting some limits in place at some stage. Shame though in some ways it's interesting to see the different design approaches each team has brought to the table.

 

And if you wan't to discuss racing mono's seaworthiness and dropping keels there's allready a few threads on that subject. So please let's not go there in this one..
BR Teddy

 

Come on Teddy, Mike was keen on a bit of thread drift I'm allowed some surely as well

 

Heres a link to an article by Ian Farrier on an inflatable masthead buoyancy bag to prevent inversion on farrier trimarans. The capsize example he quotes correlates remarkably with the Dragonfly capsize.

http://www.f-boat.com/pages/background/capsizearticle.html

Also an article on the ocean brake

http://www.oceanbrake.com/jordan'snotes.html

A personal perspective by Alan G Toone on heavy weather multihull sailing.

http://www.multihullpages.com/heavy_weather.html

A google books reproduction of Heavy Weather Tactics Using Sea Anchors & Drogues

By Earl R. Hinz

http://books.google.com.au/books?id...Bw#v=onepage&q=racing trimaran drogue&f=false

 

An interesting aspect to the capsize of rambler in this years fastnet was the water ballast accelerating the capsize from 90 degrees to 180 degrees, and 2 people got separated for the boat. Later recovered with severer hyperthermia.

Now back to the original thread, at least we have now put forward some use full books to gain some more ideas to try before they are needed.

I wonder if it would be possible organise emergency lighting if you were to capsize to activate during the action to assist with escaping on a bridge deck catamaran in conjunction with a escape hatch.

To increase safety in all situations. how ever I would still prefer to prevent the capsize in the first place.

As Mike keeps saying catamarans capsize, or does he not like our Ideas to solve the problem.

 

I have never heard of a Buccaneeer 24 capsizing or pitchpoling.
An awful lot of them were built and sailed all over the world during the past 40 years and I can't believe that none went over.
If any of you reading this thread have any input on this subject I would like to hear it. Perhaps Samnz could
comment as he has had a lot of experience pushing his "Green Death Trap" beyond the event horizon.

 

Thanks Corley for posting those links , once again more use full information being passed on.

As well as a full report on the F-27 capsize. Rather than a possibly edited report by mike, if it is not edited they appear to be edited, with no lesson at the end of a report.

I think Oldsailor7 may have a point with Samnz racing experience, with it being first hand experience.

 

It seems pretty clear to me that the monohull configuration is potentially more seaworthy than the multihull configuration in that a monohull can be designed to be both unsinkable (for all practical purposes) and reliably self righting, whereas a multihull can only be unsinkable. But of course, you would be better off in difficult conditions aboard a well designed and well maintained multihull than you would be on a monohull that has a poor range of stability, or a weak keel attachment, or weak rigging, steering system etc.

The fact that most monohulls would not reliably self right undamaged if thrown over by wind and/or wave is because purchasers dont generally demand that capability. It is not because the capability is beyond what technology could achieve. Similarly, purchasers of new monohulls that do not need to meet commercial chartering requirements don't generally demand watertight bulkheads and/or flotation material, I suppose the risk of sinking is thought to be so low that its not worth worrying about - seems it is only mulithull sailors that get concerned about monohulls sinking!

There have been a few production monohulls designed to be unsinkable, some made in Belgium, some in UK, perhaps some in other places. They never took more than a small share of the total market for sailing boats. From pictures of these boats you would hardly see a difference to a comparable boat that was not unsinkable, the only compromise being reduced locker space due to the need to use all the odd corners of the interior as bouyancy compartments. As Mike says, it is not all that hard to make an unsinkable monohull if that is what is wanted.

Another point is that the seaworthyness of a multihull is more size dependant than that of a monohull. A small fragile object such as an electric light bulb cast adrift in the sea will survive any storm. It just bobs about and mostly stays one way up if it has a metal part at one end. The smallest sizes of monohull, certainly down to 20 feet LOA and even below that, could be designed to be very seaworthy. The reason there is negligible demand for such boats is that they would be slow and uncomfortable. For multihulls on the other hand, size does tend to reduce the risk of capsize, so mitigating the weakpoint of the configuration. The waves are relatively smaller for a large vessel, and the ratio of wind forces to gravitational forces also reduces with increasing size. A few years back I read in several places that a multihull cruising yacht of more than about 40 foot overal is more or less immune to capsizing. Now that the internet has brought us more frequent reports of multihull capsizes you dont seem to see such statements so often. How big does a multihull need to be these days before the marketing people dare tell you that it is uncapsizable? Well, a Dutch firm has started to build a twin hulled ship about 380 m long - I dont think that will capsize in a hurry.

Multihulls do capsize and reports quoted on this thread have provided examples. My impression is that we have been hearing such reports more frequently in the last few years but I dont know whether that is because there are more multihulls at sea or because the capsizes are more widley publicised via the internet, perhaps it is both.

The potential for capsize is just one of the factors to be considered when choosing what kind of boat you would like to buy or build, taking into acount the kind of sailing you want to do. Motor cars also sometimes capsize, but that doesnt seem to discourage many people from travelling in them. The sailing that I would hope to do would be relaxed coastal cruising plus occasional passages across the wide end of the English channel or the southern north sea. For me, the shallow draft and possibility of taking the ground in drying estuaries are big practical advantages that are somewhat harder to realise with a monohull design. I would admit that the possiblity of good performance when reaching in nice weather is also a draw, so is the lesser rolling on a mooring or at anchor. As a potential home builder I like the idea that I could build a good sized multihull as a demountable structure with all the individual parts weighing less than a ton. I could move that amount of weight around using rollers, trolleys and perhaps a small Tirfor winch. Indeed, that is almost a prereqisite for me since I couldnt get a hired mobile crane to the area I have available for boat building. Like most people, I dont actually need a new boat, but if I do build one, a multihull is my current favourite and I have even drawn up a preliminary design as the thread 'post your own design ideas'. But right now I am hoping to spend the rest of this summer cruising with my present small home made monohull. It doesnt have a very high ballast ratio, so it will not self right from much more than 90 degrees of roll, but it is effectively unsinkable with a dozen sealed compartments that will float much more than the weight of lead in the keel - so a bit like a good multihull.

Thanks for the links included in this thread, I found Corley's recent set of links particularly interesting.

 

Thank you John for your well balanced reply.
As a monohull sailor your comments were lacking the defensive attitude which most monohull sailors display and were constructive rather than the reverse.

I was a monohull sailor for years before I saw the Light and turned to the Dark Side.
For two of those years, with my wife and two small boys, we sailed a Hartley 18 (I think it was called a "Silhouette"). It had a small cabin but no closeable companionway and a very exposed cockpit.
It had twin thick sheet steel keels, a small inboard motor and if it had ever capsized it would have gone straight to the bottom. We sailed it accordingly and had no problems, even though we braved some serious squalls.

However right after that we had a Piver Nugget. There was no comparison and I have been sold on multihulls ever since.
I think you would be too.

 

It is a bit silly.....monohulls can be designed not to sink and multihulls can be designed to be righted. I own one of each, the monohull has flotation and the tri is being evaluated for capsize recovery. They both serve a purpose but hands down a multihull is a much nicer way to sail.