Multihull Capsize Prevention <split>

The cat that capsized off the PNW coast while on delivery from Africa came ashore intact floating high upside down. If the sailors had been able to remain inside they could have stepped ashore..... However there are instances of people remaining below suffocating because no provision was made for inverted air ventilation. While the inverted cat should be able to be worked on a "safe" compartment inside should be your life raft to stay with the vessel.

 

It's a good point Cav there are conditions where you would probably not want to leave an escape hatch open for ventilation either you almost need a snorkel or a dorade box that could attach inside the escape hatch frame for ventilation when waves are sweeping the boat. It doesnt sound like the cat you mentioned had an access hatch for inverted access either. Gavin suggests having a handsaw accessible when inverted to cut access holes in the hull skin but to keep the cutout to refit when conditions get rough, seems reasonable.

 

It's up to individuals to decide what level of safety they are willing to accept the important thing is that they be presented with fair and objective information on safety and know what risks they are taking. It's also important that they are equipped with the knowledge to sail with the maximum amount of safety in a given situation these points are important. A safety handbook as you first suggested is an excellent idea and perhaps drogues, parachute anchors and the like should be offered as standard equipment. Escape hatches are fitted to most production catamarans but there could be more of a focus on inverted safety.

The rest of your post doesn't really have much relevance to the thread most production modern cruising cats do not emphasise performance and are underrigged if anything their performance is sluggish at best so I dont see where your performance claims fit. The majority are more geared towards accomodation than performance. With many having a lot of auxilary diesel power installed.

 

I think Mike just did what he said others shouldn't. It is a fact that multis are more stable upside down and monos more stable on the bottom - if they are capsized or sunk respectively.

As for the quip about monos being safer - I don't know any facts that bear this out once we have gotten rid of all the examples of bad boats. Mike may get rid of some ocean racers, I could remove charter type cats and then we could try to make up some stats. Chris White and Farrier have done some stats. In Chris White's book he relates that falling overboard is one of the major areas of fatalities from boats - something that multis with their wide decks and lack of heel should be easier to stay on board.

Mike should probably read Chris White's book where he goes into Coast Guard stats that show that a multihuller has slightly less chance of being killed than a monohuller (P 41 The cruising multihull) But sweeping statements that a well designed mono is safer than all multis is obvious IF we include dodgy multis. The problem is that there may be more dodgy muktis than you think.

We know exactly what to do to make multis safer. In the Capsize Bugaboo Jan Gougeon laments that people do not put in inverted flotation into their multis. Chamberlin also commented to me that if he designs in inverted flotation and watertight bulkheads builders and owners often rip them out to make more room. I can't understand this. The escape hatch in Mike's last excerpt about the Lagoon off Bermuda was not especially helpful as there was nowhere to be safe outside. In the Chris White example in the Pacific the crew did not get into the safe area of the boat either.

I think if you were to ask designers like Brown, Newick, White etc they would be disappointed at the marketing that has builders reducing safety by saying the boats will not sink and are hard to capsize and then not building for this rare eventuality. Even the most secure mono that Mike could design would still have a liferaft and abandon ship bag. Yet why are many multis so deficient in inverted accommodation? It can always happen yet very few multis I have been on would be anything other than a terrible wave strewn platform if inverted.

This is where tris are so much better than cats. It's very hard to design a tri that won't float well inverted but easy to design a cat that has little in the way of safe zones upside down. On this I think Mike and I can agree - the average mono is far better prepared for the worst the boat can do - sink - than the average multi is prepared for capsize. I have been on quite a few cats with escape hatches but I can't think of any fellow multihullers who can tell me where they will huddle in bad weather upside down. One friend was worried and told my wife that I was deluded because I put non skid on the bridgedeck bottom - denial is wide spread in the multi field.

I asked Robin Chamberlin to design me a super safe cat. Kankama has inverted flotation, somewhere safe to break into with an axe up out of the water if inverted, water tanks that won't drain inverted, food hatches that kept their contents any way up, a couple of axes in specified locations, a small rig, nice high bows, wide decks, a wishbone to lower sheet loadings, an inner forestay to set a storm jib on, watertight bulkheads 3.5 metres back from each bow and 2 metres from each stern, good visibility and yet none of these compromise her livability. It is so easy yet almost no one sits down when building their cat and does what our mono friends do - accept that inherent lmiitations in the concept and build to minimize the risk. So I probably agree with Mike for most of the cruising cats out there but it doesn't have to be this way. A good cat can be really safe IF you build with its obvious downsides in mind.

A final aside on the tank testing quote - we couldn't capsize the model no matter what. Jim Brown did something similar with an exact model of the Searunner. He even towed it behind a ski boat until it jumped out of the water and it never capsized. I like Searunners very much but at least three have capsized in real life even though a model handled some very extreme stuff. I would prefer to see someone take a model into the surf and see how it goes there.

 

Thanks corley for adding some common sense to the thread.

Another book of some help could be Multihulls Offshore by Rob James if it can be located it covers multihull seamanship and various capsizes, although it is more aimed at trimarans.

 

Here are a few sobering reports:



and

 

No it's not a fact at all.
I put that statement in quite aware of it's importance to some people.

It is simply not a sensible paradigm. Look at the logic of is actually compared.

So now consider and compare "Intact Stability" and then "damaged stability" and all that lies within that set of design options. You cannot mix them and cherry pick as a design comparison. A monohull can have positive floatationand a Catamaran without subdivision can sink quite quickly with no more than damage to one hull. They need positive floatation too.

The statement is one of ignorance of Naval Architecture and shows an inventive misunderstanding of stability.

 

Thanks for the advice Mike,

I do have some grasp on the concepts of psychology & agree that personal attacks are pretty uncool... that's why I called CB out over his misrepresentation of Ad Hocs discussion on another thread & was similar to another previous members skills at cut & paste with some very selective editing thrown in. That doesn't of course mean that all of CB's views should be discredited, the points made in regards to seamanship being a very important factor to safety being one, that seams to be the basis of discussion now, which is terrific. Here's a link to a "prominent" designers take on "Professional Licence" ... scroll down a little for it http://multihullblog.com/page/9/ from this I must be inept as I love stamped plans!.With all this stuff we have to consider the stance & motives of people & the application of "Learned Behaviour" that we all apply, lucky we have the Engineers logic to set the rules for important stuff in civilized countries. All the best from Jeff.

 

Great that in these scenarios that all were saved & the lessons learned, these look like fun http://www.dart18.com/ Jeff

 

The Round The island Race this year was blustery and several of the multihulls inverted . There's a great sequence of photo's of a trimaran going over.

 

Jeff
Here the PE is criminally liable if someone gets hurt and it relates to inadequate design. When we sign off on our design we accept that we can go to prison for manslaughter for no more than an oversight.

The same doesn't hold for a 'Yacht Designer' here, outside of the commercial arena anything goes for a 'yacht designer'. So a design that has been approved by class or flag offers some security. Otherwise that PE stamp does offer some valuable assurance.

 

Heres some shots of Rambler upside down in the Fastnet race for a bit of balance afterall you want to bring up racing accidents and capsizes on multihulls. Just as well it happened close to shore or there could have been fatalities. Lets look at some recent events.

http://www.sail-world.com/UK/Rambler-100-capsized-in-Fastnet---all-crew-safe/87337

Heres another where a Beneteau sank.

http://www.standard.net.au/news/local/news/general/six-men-rescued-after-yacht-sinks-near-port-campbell/2514331.aspx

 

Actually Mike it makes sense.

If you and I were to sink our respective boats - you pepper your mono and let it sink and I will pepper my cat and it will not. I have to take a few rocks and weigh it down to sink it. The at rest condition of my reasonably light weight cat with thick skins will be awash but on the surface - it will want to float if I remove the rocks. That is where it will want to lie - I think this is no real stretch to say the boat has found a stable condition - awash. (Couple of examples of multi awash with ripped out bottoms - Piver tri in Melbourne 1972, Bagatelle, Searunner in Brown's book) Like the mono in a stable condition on the bottom. The thing is the mono could be perfectly structurally sound - like Waikikamukau - the Farr 707 that killed three people when it sank off Sydney with two waves overwhelming it.

Even damaged flotation is a good thing. I met a person who lost their entire family when their mono sank after a collision. It was a very sobering experience and doesn't condemn monos - just makes me more quiet about the important things in life and makes me remember how lucky I am to be here.

I also met a guy whose mono was so slow that it got run down by a ship. I asked him why he didn't see the ship and he said he did - his mono was just too slow to get out of the way! (Hartley Ferro)

What about the other bloke I met cruising who got run down in his steel mono and so bought a little cat as a safer option.

So does that condemn monos? Of course not. It just shows that you should be careful when using them as with all boats. Ian Short dies when his maxi hits a reef with its deep keel. Bad mono? It didn't help that the low boom swept across the rocking deck but bad navigation was a more important factor. For every nasty thing that happens on a cat I can find bad events on monos. What does that prove? Nothing but BOTH types of boats have their problems and so you need to design to cater for the problems inherent in each design.

It would be silly of me to try and convert you Mike but at least have a sail on a few multis. If you get out on a few good versions you may change your mind about them. The boats talk far louder than my posts ever could.

cheers

Phil

 

What is supposed to be a thread about multihull capsize prevention is possibly again going in the direction of camps fighting each other. Doesn't some of it sound familiar? It sure does to me!
Its a non issue, it's useless comparing multihulls and monohulls because they are suppose to be different, they are supplementing each other.
Like having a bath or taking a shower.

Mike, please stop drinking that vinegar. Although serious, sailing is fun.

And for those who haven't seen it already; Lia Ditton on a memorable trip http://www.youtube.com/watch?v=1PzptVxE8is

Cheers,

Hielan

 

I thought thee round the island race was off some interest since it was blustery but the sea state was not dangerous. Several of the multihull fleet inverted. None of the monohulls did. Being a salient point that squally conditions are not conducive to flying large amounts of sail and monohulls are a lot more forgiving when overcanvassed. That's all.

As for fatigue failures of anorexic keels or lack of watertight subdivision .......of course we could fill the thread with sunken and overturned boats boats.

But this was the crux;
If we consider that A well built and properly designed multihull ( which I would count as necessarily having watertight subdivision) with a monohull with the same features.

It's as easy to make a monohull unsinkable as it is a catamaran.

My argument wasn't condemning multihulls as unsafe, it was condemning the sort pf misleading statements that get dished up.