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Old 24-12-2014, 13:45   #91
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Re: Capsized Atlantic 57 Salvaged

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Originally Posted by s/v Beth View Post
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. The mono will broach, then pop back up as soon as the wind abates.
This happens more often than people think. It has happened to me at least twice, but I sail around mountains a lot, were I think these types of winds seem to live...
BTW- I saw one of them coming (day) and one of them I didn't see (night, in fog)
Assuming boat boats survive the gust without serious damage, the force on the catamaran rigging is higher because when the mono rolls over, wind spills out the top.

Capsize vs knockdown & sink: This isn't really related to sizing of the rigging. No one designs the rigging to handle either of these conditions. If you go back to the graph posted earlier, the righting moment is for similar size vessles but you will notice the cat peaks much higher but is reached quickly and then it quickly drops off. This is why you reef a cat to the gusts and a mono to the steady wind.
- If you reef the cat to the steady wind and are pushing hard, the gust may exceed the peak righting moment and at that point even with the wind spilling off the top of the sail, there may be enough overturning moment to keep her going over.
- The mono on the other hand just heels over a bit more for a few seconds spilling the wind out until the gust passes. In the extreme, it heels over almost 90 degrees, spilling almost all the wind (but god forbid you have a hatch open or a port fails while under water)

Both are reasonably safe assuming they are sailed appropriately but the cat of similar size needs heavier rigging.
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Old 24-12-2014, 14:30   #92
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Re: Capsized Atlantic 57 Salvaged

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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...
Our experience having owned, lived on and cruised both types, is that we can average much higher speeds in the cat, while still sailing far more conservatively.

We always reduce sail at night. In any given wind strength we'd be carrying less sail on our cat than we would have on our mono.

Conditions which can cause a mono to be knocked down can be virtually a non event in a cat.

We were knocked down twice in our mono on day sailing into port stephens in a strong (25 knot) north easterly. Bullets of 35 knots plus off the headland hit us, and the boat rounded up and laid over.

On a stronger day we sailed the same course in our cat. When the bullets hit we simply accelerated. The higher boat speed reduced the apparent wind to easily manageable levels. Where our mono had been sailing at around 5 knots between the bullets, the cat was sailing closer to double that.

If these types of gusts were a real threat, you see far more cruising cats being blown over. It simply doesn't happen that often. It's not because cat sailors are some kind of supermen, or more highly skilled, or more attentive. In the Whitsundays you often have days of 30+ knot weather, and on those days you still see plenty of chartered cats, even quite small ones, out there sailing across the passage with wind against tide causing steep beam seas, and with full sail up.

If cat's were as dangerous as people (who almost universally have never sailed on one) in forums make out, they'd be capsizing in their droves. They aren't.

BTW the rigging wire on our 44' cat is the same size as we had on our 40' mono.
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Old 24-12-2014, 15:19   #93
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Re: Capsized Atlantic 57 Salvaged

Duly noted 44CC. As I said, once I stop sailing high lat locations, I will be in a multihull. Until then, Alaska calls this year.
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Old 24-12-2014, 15:28   #94
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Re: Capsized Atlantic 57 Salvaged

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As I said, once I stop sailing high lat locations, I will be in a multihull. Until then, Alaska calls this year.
Why wait?
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Old 25-12-2014, 08:46   #95
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Re: Capsized Atlantic 57 Salvaged

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It can be done, cheaply and easily. Attach the mainsheet block to the boom using spectra of a breaking strain that will fail before loads get to the point of capsize.
Good idea.
However, what about shock loads like an uncontrolled gybe? I imagine those could exceed the static loads of a wind gust. Sure wouldn't want the loose boom slamming into the rigging...


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Old 25-12-2014, 09:04   #96
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Re: Capsized Atlantic 57 Salvaged

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Good idea.
However, what about shock loads like an uncontrolled gybe? I imagine those could exceed the static loads of a wind gust. Sure wouldn't want the loose boom slamming into the rigging...
And there is the lee shore thing. There are times when you need or want to point as high as possible by pushing as hard as possible. An experienced cat sailor can be quite comfortable sailing near the capsize point under the right conditions, feathering and trimming as need be, with the windward hull rather light. Many of us cut our teeth racing beach cats, keeping the weather hull just skimming or flying low the entire windward leg. In strong winds, aggressive sailing can make the best VMG. A fuse would make this impossible, and that is another sort of safety problem. (This is not universally true--some will overload the foils and should reef earlier. Proper balance is also important when sailing at the limit and is often overlooked--the boat is said to have spun out of control due to rudder cavitation, when in fact she was not properly balanced for the conditions. If you have to manhandle the wheel, something is wrong.)
When it's gusty I keep the sheets and traveler out of the self tailers and in cam cleats, make certain the sheet tails are clear and at arms length, and the boat is hand steered. Feels safe to me.

For non-cat sailors, one advantage of full batten mains is that they feather very well and do not flog. The typical cat main can take some very strong gusts feathered without acting up, so long as the wind is forward of the beam. They are also cake to reef, as they stack very easily. Reefing early is still better.
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Old 25-12-2014, 10:44   #97
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Re: Capsized Atlantic 57 Salvaged

This thread is great- and really illustrates compromises inherent in each boat type.
To get the real speed difference cats need to be light and powerful. Means risk of capsize is greater, placing more of a premium on safety and also reducing sail early. That's a lot of work with large sails, but made easier by electric winches, etc
Performance oriented monos can do very well on passage, and if good seakeeping habits are followed, like closing hatches, are probably safer in sudden freak microbursts as they will only be knocked down. With hatches closed, no downflooding or swamping.
Cruising cats are heavier, with smaller sail areas. They will be decently fast on passage in good breeze, but will often wallow in light airs. Some of this is due to no heel in light winds to help fill the sails. Minimal capsize risk though, but speed difference compared to monos is minimal or negative.


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Old 25-12-2014, 17:41   #98
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Re: Capsized Atlantic 57 Salvaged

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... A responsible multihull skipper would never sail through a squall on autopilot with significant sail up. I've sailed cats though lots of squalls, and you just don't do that. Autopilot is for settled conditions. Thus, capsize will only happen when the waves are wild, in which case a float only INCREASES the likelyhood of capsize (weight and windage) and insure the rig is coming off.
...
I don't want to go this way but you continue with that strange theory that capsizes only happens on cats when waves are wild and that is simply not true. I have been following through the years boat accidents and capsizes in cats and monohulls and in what regards cats most capsizes happened on normal seas due to very strong gusts. I have heard of many more, some does not come to the net but here you have just some examples on cruising cats:

Here you can see a movie (on the link below) with a capsized big French cruising cat. As you can see the sea is calm:

"Two women and five men were trapped inside the yacht after it upturned suddenly, they managed to escape onto the hull.
The incident unfolded so quickly that the crew were unable to call for help on their radio or release a distress flare."


Video: Seven French sailors rescued off the Isle of Skye - Telegraph

"The craft's emergency beacon raised the alarm at about 21:00 on Wednesday. A sudden gust of wind was thought to have tipped the yacht over.
None of the catamaran's crew was injured and they spent the night at the Fishermen's Mission in Mallaig. The yacht was towed to Skye.
The RNLI said the capsize was so sudden that all onboard the yacht were trapped in the hull.
They managed to escape onto the upturned hull."


BBC News - Seven rescued after yacht capsized off Skye

And here you can see a capsized 47ft crewed charter cat:



As you can see the conditions (3 hours later) were far to constitute any risk to any cruising boat (F7/8) when:

".... The sails were raised halfway and the boat set off again.. at 2:15 p.m., a strong gust blasted the boat and Brenda Smithee said she saw her husband fall overboard. "We tipped over really fast. There was absolutely no time to react," she said....
Weather Service small-craft advisory was in effect with winds of 20 mph to 30 mph.
"

I could post more about similar accidents, some with very experienced sailors but my point is not to say that cats are unsafe neither that these accidents are frequent (in fact they are rare), my point regards only saying that you are wrong when you say that ""capsize will only happen when the waves are wild"". Capsizes on cats, including heavy cruising cats can happen (has reality shows) even in almost flat seas due to very strong unpredictable gusts.
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Old 25-12-2014, 17:49   #99
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Re: Capsized Atlantic 57 Salvaged

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Cruising cats are heavier, with smaller sail areas. They will be decently fast on passage in good breeze, but will often wallow in light airs. Some of this is due to no heel in light winds to help fill the sails. Minimal capsize risk though, but speed difference compared to monos is minimal or negative.
Just be careful which cat you pick a fight with. Let me know when you're ready....

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Old 25-12-2014, 18:05   #100
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Re: Capsized Atlantic 57 Salvaged

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.. 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? ....
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The wind force on the sails will be the same by a small fraction of a second and then the monohull will spill the wind by heeling while the cat will take all the force on the rig, not during a small fraction of a second but for all the time the wind blows, it may be for hours. Certainly you can see that there is a difference between the consequences of a force applied on a mast for 1/100 of second, for minutes or hours?

Besides that, when the mono is knocked down the wind is passing over the hull and an increase on the wind will have no influence on the pressure on the mast, while on the cat that increase in wind force will correspond to an increase on the pressure sustained by the cat mast.

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Old 25-12-2014, 18:08   #101
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Re: Capsized Atlantic 57 Salvaged

^^ I stand by what I said. You skipped right through my caveat "responsible." Even experienced sailors become lulled by the security of a large boat into really poor decisions. Each of the sailors mentioned was momentarily irresponsible, carrying more sail than needed and not reacting correctly.


The notion that force 7/8 is not enough to cause concern, once gust are considered, proves my point. That is absolutely enough that gusty wind precautions should be in place. The attitude proves my point. I've never seen a boat-flattening gust that the helmsman could not have seen on the water or felt, had he been attentive. hidden away in a protected pilothouse... not so much.

So long as the sailor remembers the limits of the boat and the reactions required on more tender cats, this will not happen. In every case, someone was asleep at the switch. Perhaps I am timid or overly careful in the eyes of some, but I have NEVER felt endangered by gusts, whatever the strength. Only breaking waves are truly scary.

There is no defense against inattention. Yes, cats are more demanding in this way. That is a part of the design compromise. Anyone who says otherwise is selling something.


My concern with a "fuse" is that it cannot sense changes in wind direction, which may be important to the correct response. But it is an interesting area for development.
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Old 25-12-2014, 18:15   #102
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Re: Capsized Atlantic 57 Salvaged

Correct me if I am wrong, but it seems like Cats need less force to turtle than a tri. I am thinking because most of the weight is in the two hulls, and when a cat starts to turn over literally half of the weight is in the hull that is the pivot point and thus not a force in keeping the Cat upright. Tri's have most of the weight in the middle, thus when flipping it has most of the weight trying to keep it upright until 90 degrees or so is reached. Also are tri's wider per lenght than the 1:2 ratio that we hear so much about?
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Old 25-12-2014, 18:23   #103
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Re: Capsized Atlantic 57 Salvaged

OK, forget the "fuse"
Why not a winch with an adjustable "drag" just like a good fishing reel, if it starts to creep out, add a little drag, get hit with a big gust of wind, just like a the fishing reel, it lets out line? I'd like that on my mono hull.
My Penn SW30's are even two speed, couldn't be hard to scale it up?
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Old 25-12-2014, 18:26   #104
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Re: Capsized Atlantic 57 Salvaged

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Correct me if I am wrong, but it seems like Cats need less force to turtle than a tri. I am thinking because most of the weight is in the two hulls, and when a cat starts to turn over literally half of the weight is in the hull that is the pivot point and thus not a force in keeping the Cat upright. Tri's have most of the weight in the middle, thus when flipping it has most of the weight trying to keep it upright until 90 degrees or so is reached. Also are tri's wider per lenght than the 1:2 ratio that we hear so much about?

From what I've heard, a catamaran is more likely to capsize due to wind, where a tri is more likely to trip over its ama and capsize due to wave.
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Old 25-12-2014, 18:42   #105
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Re: Capsized Atlantic 57 Salvaged

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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.
For what is worth I have been following on the ARC for several years the performance of boats, with particular interest the performance of cats, performance cats and condo cats versus monohulls and I have reached some conclusions, that may be right or not but that has as basis the observation of many hundreds of sailboats while doing a transat on the trade winds.

I believe you are wrong in assuming a modern cat of about the same size will not have a considerably better performance regarding your boat, and for that I mean several days on a Transat (condo cats or performance cats).

I think you are right in assuming that to sail a cat very fast it will be needed very experienced sailors and a crew that allows a constant vigilance over the
wind conditions and that is much more racing then cruising. That's why on the ARC average cats of about the same size are just slightly faster than mass market monohulls and considering performance cats, about as fast as performance monohulls of the same size while cruising loaded on the ARC. Off course the ARC is a downwind ride and while going upwind things would turn better for monohulls than for multihulls.

Off course we can see from time to time multihulls being sailed, or raced at a very high level and then they can be faster downwind than similarly sized performance multihulls but that level of skill (and needed crew) is so rare that this year on the 2 ARC you have saw only a performance cat sailed like that, this one:

a 45f boat that made equal game with a fast 61ft monohull while all the other (many) theoretical has fast or faster performance cats just made equal game with similarly sized performance monohulls of the same size.
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