Atlantic 57 Catamaran Capsized

[Training Wheels]

Ya think!

[StuM]

Originally Posted by boatman61

Ahah..!! ya must be a 'Mono-man' at heart

You are possibly missing a terminal "iac"

[Polux]

Originally Posted by neilpride

As a side note, in SA fórums are discusing some ideas about how to implement reléase devices in winches to dump the sails in a fuzz in case of a fliping scenario... and i dont know why this things if they exist are not mandatory in multihulls... seems a good idea no?

Racing ocean trimarans use them but they don't always work. Better than nothing but I would not be alarmist in what regards cat capsizes. The problem is only significant in what regards a very small proportion of the cats on the water, the more sportive ones.

[44'cruisingcat]

Originally Posted by boatman61

Ahah..!! ya must be a 'Mono-man' at heart

I said a BIT slow! No need to be rude!

[robert sailor]

Originally Posted by smj

Re read the thread and what the crew had to say. Aren't they the only ones who would know?


Sent from my iPhone using Cruisers Sailing Forum

Yes I agree with you but all I recall was the noise made from the wind and the boat going turtle, don't recall any description of actual wind speed, other than too much of course. R

[Polux]

Originally Posted by arsenelupiga

maybe french play more with wind tunnels. To my surprise, my fat lagoon tacks EVERY time without problem. This was not the case with some not that much older cruising/performance cats i was testing.

I had a look at the boats in question, performance cruising cats that have a big percentage of capsizes regarding the number of boats built: Atlantic 57, TS52 and Chamberlain 14 (45ft) and the ones with about the same size that have an incomparably smaller number of capsizes, or not at all, the Outremer 5x, the Catana 53 and the smaller Catana 42.

I agree partially with some that said that if a boat is easy to reef and has an adequate number of reefs and not a vastly exaggerated sail area, the problem is not probably there and it don't seems to be the case with any of these boats.

In what concerns the keels, even if it can have some influence regarding the Atlantic 57, on a capsize due to a big squall or any other phenomena with violent and sudden winds but no considerable waves, that influence would be much smaller than if waves were involved.

Don't having access to the stability curves I used the simplified formula that is referred by catsketcher

Originally Posted by catsketcher

... Stability is displacement x 0.5 the beam. ..

that on the cases of cats with not very different design (performance cats), will give results that can be used to have a general idea, since the boat's center of gravity will not be very different.

I believe that the results contribute to explain why Outremer and Catana experience much less problems. They are considerably heavier and as the displacement is two times more important than beam for stability (and the beam is similar), the stability of the boats is different, even if they have the same size. Maybe that in conjunction with the keel design.

An Outremer 5x or and a Catana 53 has more 18% and more 20% stability than a Atlantic 57.

Regarding the TS52.8 compared with the Catana 53 the diference is much bigger, having the TS52.8 about 2 times less stability.

Comparing the Chamberlain 14 (45ft) with a smaller Catana 42, the Catana has about more 65% stability.

Outremer starts his range of fast offshore catamarans with 45ft, Catana with 42 suggesting that those boats with that displacement is what the consider to have a suitable margin in what considered stability and safety.

Both brands had in time smaller offshore catamarans and they have discontinued them.

Using this formula the stability a Lagoon 560 would have almost 3 times (2.8) more stability than an Atlantic 57. Here that formula will not give accurate results because the Atlantic will have a lower CG, but the Lagoon will have probably more than two times the stability of an Atlantic 57.

That of course does not mean that an Atlantic 57 is not suitable for cruising but one needs to know that the risks of a capsize are a bit bigger than in other heavier performance cruising cats and uncomparatively bigger than the ones on a condo cat type Lagoon. Sometimes size can give a false idea of stability in what regards catamarans, if they are very light.

[arsenelupiga]

Originally Posted by Polux

I had a look at the boats in question, performance cruising cats that have a big percentage of capsizes regarding the number of boats built: Atlantic 57, TS52 and Chamberlain 14 (45ft) and the ones with about the same size that have an incomparably smaller number of capsizes, or not at all, the Outremer 5x, the Catana 53 and the smaller Catana 42.

I agree partially with some that said that if a boat is easy to reef and has an adequate number of reefs and not a vastly exaggerated sail area, the problem is not probably there and it don't seems to be the case with any of these boats.

In what concerns the keels, even if it can have some influence regarding the Atlantic 57, on a capsize due to a big squall or any other phenomena with violent and sudden winds but no considerable waves, that influence would be much smaller than if waves were involved.

Don't having access to the stability curves I used the simplified formula that is referred by catsketcher

that on the cases of cats with not very different design (performance cats), will give results that can be used to have a general idea, since the boat's center of gravity will not be very different.

I believe that the results contribute to explain why Outremer and Catana experience much less problems. They are considerably heavier and as the displacement is two times more important than beam for stability (and the beam is similar), the stability of the boats is different, even if they have the same size. Maybe that in conjunction with the keel design.

An Outremer 5x or and a Catana 53 has more 18% and more 20% stability than a Atlantic 57.

Regarding the TS52.8 compared with the Catana 53 the diference is much bigger, having the TS52.8 about 2 times less stability.

Comparing the Chamberlain 14 (45ft) with a smaller Catana 42, the Catana has about more 65% stability.

Outremer starts his range of fast offshore catamarans with 45ft, Catana with 42 suggesting that those boats with that displacement is what the consider to have a suitable margin in what considered stability and safety.

Both brands had in time smaller offshore catamarans and they have discontinued them.

Using this formula the stability a Lagoon 560 would have almost 3 times (2.8) more stability than an Atlantic 57. Here that formula will not give accurate results because the Atlantic will have a lower CG, but the Lagoon will have probably more than two times the stability of an Atlantic 57.

That of course does not mean that an Atlantic 57 is not suitable for cruising but one needs to know that the risks of a capsize are a bit bigger than in other heavier performance cruising cats and uncomparatively bigger than the ones on a condo cat type Lagoon. Sometimes size can give a false idea of stability in what regards catamarans, if they are very light.

this is certainly most important factor. However, wind and wave simulations (and massive feedback from cat users) can provide extra feedback how to improve stability. I believe waterline hull width improves stability further because minimizing immersion, but it is considered bad for performance.

People that buy performance cats must be prepared for (and never forget) iron discipline to keep boat light and be on watch more. No romantic dinners on front net allowed during sail.

[44'cruisingcat]

And the rubbish keeps piling up...

[arsenelupiga]

Originally Posted by 44'cruisingcat

And the rubbish keeps piling up...

we all get complacent here and there, reminders of our limitations should not be interpreted as impolite and should not be ignored.

[TeddyDiver]

Originally Posted by Polux

Sometimes size can give a false idea of stability in what regards catamarans, if they are very light.

Well said..

[44'cruisingcat]

You don't need iron discipline, and you don't need to keep your hand on the mainsheet 24/7.


Does every monohull (or heavyweight sinkable cat) sailor scan the water surface 24/7 on the lookout for semi-submerged shipping containers?


A bit of reality - yes I'd reef earlier than you would. And you'd start your engines sooner than I would. The extra performance is really just having another gear, which can be used in lighter winds.

[Jim Cate]

Back to the possibility of wind-only inversion:

I remembered an incident that may have some bearing on the discussion. Some years ago, early 90's I think, some friends of ours, cruising in a Bristol 29, went through a super typhoon direct hit in Guam. They were in the official safety lagoon (or whatever the title is), moored from 4 big blocks on the lagoon floor. The official wind velocities were reported in the vicinity of 200 knots (I don't remember exactly), and I don't know at what altitude those velocities were measured. However, I think we could agree that this represents an extreme case, one not likely to be exceeded by any cruiser.

The lagoon prevented the buildup of really big seas, but I imagine it was a "bit lumpy". Our friends, on the boat "Lokalani" were held heeled to around 70 degrees for long periods by these winds. It was terrifying, and at that heel angle, their sink was well below the WL, and was busy trying to flood the boat... and they could not reach the seacock with the boat in that attitude... really scary!

But the point is that even in winds of that strength, they did not invert. They had been advised to leave the mooring lines quite slack to allow for wave action. It is possible that nonetheless it was the lines that limited their heel, but they did not believe that to be the case. I was not there and do not have an opinion on that aspect.

The argument that the reason that there are no reports of wind-alone inversions is that the boats all sank with all hands is kinda specious. There are plenty of reports from boat that were inverted by combined wind and sea...why would the crews of all those done by wind alone perish?

Of course, none of this has much bearing upon the fate of the Atlantic 57s, so I'm prepared to drop the issue and hope to learn something about catamaran stability and the Chris White designs in particular.

Jim

[PhiSig1071]

The talk about the Chamberlain not being a race boat because it doesn't have an interior as sparse as an IMOCA is disingenuous at best. The IMOCA boats have their ballast in the keel, and excess ballast in the hull (in the form of features) negatively impacts performance. Cats need a certain amount of ballast for stability, but due to the design that ballast can take the form of beds, heads, stoves, etc. If they have a gen set and AC, that's questionable as a race boat, but the design of cats allows a boat of significant performance to have features you wouldn't find on a mono.

[downunder]

Originally Posted by PhiSig1071

The talk about the Chamberlain not being a race boat because it doesn't have an interior as sparse as an IMOCA is disingenuous at best. The IMOCA boats have their ballast in the keel, and excess ballast in the hull (in the form of features) negatively impacts performance. Cats need a certain amount of ballast for stability, but due to the design that ballast can take the form of beds, heads, stoves, etc. If they have a gen set and AC, that's questionable as a race boat, but the design of cats allows a boat of significant performance to have features you wouldn't find on a mono.

[Polux]

Originally Posted by PhiSig1071

The talk about the Chamberlain not being a race boat because it doesn't have an interior as sparse as an IMOCA is disingenuous at best. The IMOCA boats have their ballast in the keel, and excess ballast in the hull (in the form of features) negatively impacts performance. Cats need a certain amount of ballast for stability, but due to the design that ballast can take the form of beds, heads, stoves, etc. If they have a gen set and AC, that's questionable as a race boat, but the design of cats allows a boat of significant performance to have features you wouldn't find on a mono.

That is very naive. A racing boat is as light as it can be, being it a monohull or a multihull.

It is not only IMOCA that have a bare interior, incredibly spartan, with the minimum to live aboard for ocean passages, all racing boats do, including multihulls. Look at the interior of some racing multihulls:

Here you have the interior of a 100ft racing multihull adapted for short handed sailing. Look at the galley (on the floor and "cabins")


This is the interieur of Macif, Gabart's racing maxi multihull


Another two interiors of racing multihulls:




But you have a point there regarding the risk of capsizing and the need of stability but that does not result in making multihulls slower adding weight, but limiting the useful size a truly racing multihull can have for really ofshore races like transats. That size is about 50ft and even those are really a handful to handle and very spectacular boats.

But the fact that none of them (50ft) has risked a circumnavigation tells about the limitations of racing multihulls of that size regarding unlimited offshore sailing, on places where high winds and huge boats are to be expected.

Off course you can race heavier and smaller performance cruisers or cruiser racer like the Chamberlain 14 offshore (45ft), as you can race a performance monohull but that does not make then racing boats. It is not the use that is given to a boat that defines is type but the design criteria that has been on its origin.

A racing boat is designed only for racing and optimized in any aspect regarding speed optimization. A performance cruising boat like the Chamberlain 14 is a compromise between performance and cruising amenities.