Capsized Atlantic 57 Salvaged

[thinwater]

Originally Posted by s/v Beth

In spite of all the above arguments, it becomes clear that if you take two similar sized boats going 5knts in wind and there is a microburst that brings 60 knts of wind within a minute, the cat is more likely to flip....

Actually, there is one reason this may not be true. I've watched many monos swamp while I was fine.

The reason is experienced cat sailors--particularly those that cut their teeth on tender cats--are very wary of microbursts within squalls. IF the wind is 5 knots and a storm is aproaching, all the sail comes in (at 5 knots you are drifting, not sailing), the deck is squared away, and the skipper is at the wheel. An expereinced skipper is never surprised; he expected the possibility and over prepared.

And under bare poles he has a nice wide, sheltered, 2-engine platform that he can easily point into any squall at very low speed. I've seen 50+ knots on the Chesapeake, and the crew remained in the salon, calmly watching the fury and reading. 40 knots they might not even look up. These were short term squalls with no important wave action.

[2Hulls]

Originally Posted by Polux

I believe you have not showed anything by the simple reason I believe you are wrong and I believe it will be easy to prove:

Just imagine two boats with an equal rig, a cat and a monohull, subjected to a gust that will knock down the monohull and will not capsize the cat. Obviously, being the monohull knocked down the wind is not making any effect on the sail or on the mast, but will be hitting with full force the sail on the cat that due to the bigger stability is able to counter act it with a relatively small angle of heel. The mast on the cat will be subjected to a much bigger effort than the one on the monohull.

Let me try again. I may have been wrong, but not for the reason you state. You're describing the forces after the knockdown has occurred, not when the forces are applied.

First, I was addressing the assertion that cat rigs sustain higher forces than monos because they don't heel as much - they have to "stand up" to the forces. This was not about knockdowns and capsizes, but I'll use your example anyway.

"Just imagine two boats with an equal rig, a cat and a monohull, subjected to a gust that will knock down the monohull and will not capsize the cat."

Assume the gust arrives as a step change in wind speed and increases no further.

OK, as the same gust hits the same size sail areas on both vessels - trimmed the same - the forces are the same, right? How can they not be?

Per your assumption, assume the mono will get knocked down. As the knockdown proceeds the forces on the mono rig obviously decrease. But they were there, equal to the forces on the multi rig when the gust arrived and continued. As the multi heels slightly but does not capsize - even if it doesn't heel at all - the forces on the rig cannot possibly increase further if the gust remains the same. How can they? (absent consideration of increased apparent wind as the multi accelerates) More simply stated, "not heeling" does not increase wind forces.

As for forces on the individual rigging components, that's another discussion. The forces on the multi rig components - at least some of them - can be less than the counterparts on the mono due to the multi's wider beam that allows greater angles from vertical and, thus, lesser tension.

2 Hulls Dave

[thinwater]

Discussing rig loads s rather like discussing whether a car or a pick-up is harder on axles; when each is designed properly, they both hold up just fine. Comparing them is fruitless, since there are too many variables in build and useage.

The Atlantic capsize was simple pilot error, compounded by a high performance design. If they had lost her on a reef due to deep draft and poor navigation, we wouldn't be tearing monohull design apart. Pilot error can happen to any of us, has happened to most of us, and we should try to learn from it. Boats of all types have been lost in short, brutal squals. I've listened to the mayday calls.

[s/v Beth]

Originally Posted by thinwater

The Atlantic capsize was simple pilot error, compounded by a high performance design. If they had lost her on a reef due to deep draft and poor navigation, we wouldn't be tearing monohull design apart. Pilot error can happen to any of us, has happened to most of us, and we should try to learn from it. Boats of all types have been lost in short, brutal squals. I've listened to the mayday calls.

I think this is the crux of the thread for me.
I have nothing against cats. I have owned them, and my next cruiser will probably be one. But I sail often solo, almost always shorthanded and around the clock. My impression is that monos such as my Valiant are much more forgiving of pilot error in the open ocean, ie I can sail with a fair amount of sail up at night with confidence that I can take down the sails if and when the winds pipe up.
I know I don't go as fast, especially when the wind pipes up and the swells are down.
And I really wish at times I had less draft.
But I can sleep with a newbie at the helm and we are in the north pacific. Well sometimes...
BTW :any ocean sailor who is as alert as mentioned above ought to do well in whatever he is sailing...

[a64pilot]

Dave,
What you say would be true if the gust was instantaneous, but they aren't. With the one I got hit with in the helicopter we had a data sample rate of out 10 per sec if I remember right, it took almost two sec for the wind to peak, may not seem like much, but two sec is a long time.

Doesn't matter in truth, I've not heard of a rash of dismastings of multi hulls, so they are obviously designed to take the loads, whatever those loads may be.
I don't own a multi so I have not been following them very closely, but unless I'm mistaken, the few that have been "blown' over have gone over, mast intact, so it would seem that the rig is more than strong enough, any additional strength would mean more weight and or expense? So it's kind of a mute point if they sustain higher loads or not, as they were obviously meant to take it, and service history has shown that if fact they can?

[clockwork orange]

[QUOTE=valhalla360;1706207]The force of the gust does exist but the mono bleeds it off by rolling. The cat tries to stand up to it.

It's similar to crumple zones on a car. A cat is like an old solid body on frame car. If you hit a brick wall, the entire car comes to a stop almost instantly imparting a huge amount of force on the occupants (F=ma and a is huge). In newer crumple zone cars, they spread that same load out over a longer time period and reduce the force applied (by spreading it out over time, a is drastically reduced and therefore the force is reduced).

When a gust first hits a mono that is fully upright, there is very little resistance to heeling so the initial force is converted mostly into rolling. Then it gradually loads up the rigging until it reaches equilibrium.

When a gust hits a cat, there is just the slightest amount of heeling and then the rigging must resist the full force of the wind.[/Q

Both the cat and the mono must absorb the initial gust, they just handle it differently, the mono bleeds it off by heeling over until less sail area is presented while the cat bleeds it off by accelerating forward, at least thats what happens with fast cats such as beach cats and net and tube cats but not necessarily so on condomarans. Another factor is rig design, many cats have essentially 3 stay rigs similar to beach cats so they have a single, massive side shroud/backstay while a similar sized monohull will have the loads divided between 3 or more stays per side plus a backstay so of course they can be smaller.

Steve.

[clockwork orange]

Hugo Meyers, one of the early designers of high performance cats used to sell a pendulum sheet release device over 30 years ago, it would not be difficult to make such a device. There have been a number of other very inexpensive sheet release devices sold over the years, I have a couple up in my attic that I picked up at a consignment store in Florida that involve a large clamcleat on a hinge board with a latch that is supposed to release when hit by a gust allowing the board which is hinged on the forward edge to flip up so the sheet releases out of the cleat. They were definitely a commercially made product that should work although I don't know what determines the release load to trip the latch. This device would obviously need to be installed ahead of the winch like a rope clutch would be and the line would need to be off the winch, flaked and free to run without getting tangled but this is just good rope management that should be practiced on any boat anyway. The simplest idea I have seen was simply using a black plastic clamcleat with a hole larger than the line drilled horizontally fore and aft just above the base, the idea is that it acts as a fuse, so when a shock load is applied to the line it is forced further down into the cleat by the angled teeth but the cheeks will flex apart and the rope will fall into the hole you drilled and be free to run, again, ahead of the winch and good housekeeping required, if the line gets tangled in something as it inevitably will this will not work but it is sure a cheap solution.


Steve.

[thinwater]

Originally Posted by s/v Beth

... But I sail often solo, almost always shorthanded and around the clock. My impression is that monos such as my Valiant are much more forgiving of pilot error in the open ocean, ie I can sail with a fair amount of sail up at night with confidence that I can take down the sails if and when the winds pipe up....

Yes. What he said. In general, cats require more attention to sail well, as there is less feedback. Good ones reward the sailor with speed all around the course, poor ones not so much.

My solution, the few times stopping for the night was not practical, was to reduce sail a little, cat nap through the day, and stay more alert during squalls and at night. However if I felt I needed extended sleep, I would probably just go bare poles, either with a sea anchor or adrift, depending on the wind direction and strength. I know better than to leave a cat to her own defense. A minor weakness at most, for a coastal sailor. If I were planning to cross oceans alone, I would give serious consideration to a mono. But for now, I would rather cross an ocean in an airplane.

[cal40john]

Originally Posted by thinwater

Actually, there is one reason this may not be true. I've watched many monos swamp while I was fine.

The reason is experienced cat sailors--particularly those that cut their teeth on tender cats--are very wary of microbursts within squalls. IF the wind is 5 knots and a storm is aproaching, all the sail comes in (at 5 knots you are drifting, not sailing), the deck is squared away, and the skipper is at the wheel. An expereinced skipper is never surprised; he expected the possibility and over prepared.

And under bare poles he has a nice wide, sheltered, 2-engine platform that he can easily point into any squall at very low speed. I've seen 50+ knots on the Chesapeake, and the crew remained in the salon, calmly watching the fury and reading. 40 knots they might not even look up. These were short term squalls with no important wave action.

What do you do at night? I've been hit by a squall at night with no warning (on a monohull). It took a couple of minutes to get the sails down. We had a little less sail up than we would have had in daylight so we wouldn't have to deal with a sail change at night if the wind came up some, but it was way too much for the 15 minute squall that hit us. To be prepared seems to require a radar or motoring with the sails down at night.

[s/v Beth]

I agree with the above. It is perhaps why Cat cruisers do not do much over 200 mile days, even though they should just blow the doors off monos.
This has been an interesting discussion because people have not resorted to hyperbole and unfounded opinions. I am grateful. I learned a lot.

[2Hulls]

Originally Posted by cal40john

What do you do at night?

Same as the day with an extra reef (usually).

Having done many multiple-day, offshore passages, a reasonable approach to nights is to, first, know the weather forecast. Then plan accordingly. Pretty straightforward. Having said that, I don't solo offshore and don't like to solo anyplace. I don't have to as The Admiral is involved whole hog, for which I feel fortunate. And we take one or two extra crew on long passages. Much easier and more fun.

Mr. Newt, I don't understand this statement: "It is perhaps why Cat cruisers do not do much over 200 mile days, even though they should just blow the doors off monos." Care to clarify?

Just about all large cruising cats are capable of 200nm days, and I've done my share (as well as leaving mono buddy boats far behind ), but this is more a function of weather than the boat. And a 200nm pace is often not very comfortable. An exception is the 25 knot + downwind run with large rollers for carefree surfing under headsail alone and boards up. A very comfortable sleigh ride with no threat of broaching. The AP loves it...

2 Hulls Dave

[Sand crab]

I'm the OP, remember me? This thread has drifted as many do and I'm certainly guilty of that like most here but I'll try to steer it back on target.
Now that we know the boat was salvaged anybody know anything about it? I suspect it probably went to New Zealand because Tonga's not really a cat refit center. Where would it be in either country? Where exactly does that ship put in? And do we have any members there?




BTW the link in my first post had questions about the insurance payout. He was paid in full for Anna and quite happy about it. That is in the link in my next post.

[s/v Beth]

2 Hulls, don't misunderstand me. I am just saying with a cat going 15-20 knots they aught to do much better than 200 mile days (300 + maybe?) but I do not see them turn in those type of numbers because of speed and potential problems seem to be related. You answered that yourself. I turn in 150+ mile days on a boat worth one third yours, and I am comfortable.
I understand what I am saying, I think. ( I guess that is all that matters )

[2Hulls]

Originally Posted by s/v Beth

I am just saying with a cat going 15-20 knots they aught to do much better than 200 mile days (300 + maybe?) but I do not see them turn in those type of numbers because of speed and potential problems seem to be related.

And you won't see any mortal cruising cat turning in those numbers. 15 kts would be 360nm. The fastest I've ever sailed my boat (not surfing) was about 14.5 kts for a minute or so. The fastest multiple day offshore passage we ever turned was an average speed of 7.5 kts, St. Thomas to Ches Bay. A typical multiple day passage for us averages about 6.5 kts. It's not the boat, it's the weather.

2 Hulls Dave

[s/v Beth]

Agreed Dave. Here in the PNW offshore I rarely average above 5 knots. Its the weather, and we both respect what it can do to our boats. I think this was just a revelation for me, because I always though cats would just blow the doors of my boat in any conditions, but she can hold her own when going to windward and the swells come up.