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Old 20-08-2010, 10:10   #241
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Atlantic 55 Comments

While my family and I spent a year sailing our Atlantic 55 over 8500 miles, I consider myself a beginner on it and catamarans in general. I have sailed Hobies and charter cats a fair bit, but nothing offshore before this one. I have, however, sailed over 100,000 miles in mono-hulls (first Atlantic crossing in 1969).

For me, the old "saw" about setting your sails to the lowest expected wind speed in a mono-hull and to the highest expected wind speed in a catamaran says a lot about the differences in managing the boats. Given that the highest "expected" wind speed is both a guess (or, hopefully, a sound judgment) and without practical limit on the upside, setting the right sails was, for me, more of an uncertainty on a cat than on my mono-hulls. This is another way of saying that, for me, a mono-hull was more forgiving of an error in picking the right sail combination.

A person could increase his or her margin of error for a wind driven capsize (the “forgivingness”) on any catamaran by decreasing the size of its rig and vice versa. Obviously, this is a true statement for a mono-hull too, but, in my opinion, it is a more powerful lever on a catamaran.

On our trip from the Bras d'Or Lakes in Canada direct to Bermuda in September 2009, we chose to leave on the back of a front. Our winds were a steady 30 knots, which meant lulls to 20 and gusts to 40. We were reaching with double reefed main, staysail and the windward board down. The seas were not unusually big for these conditions, but very confused as we came out around Sable Island. The water is shallow (in the macro sense -- 75' to 250') causing the currents to swirl around. I felt very comfortable with this rig. Had the wind increased to over 60 knots in one of the squalls that we experienced, the boat would have handled it fine. I would have headed off some more, eased the main sheet, pulled another reef (which we could do just fine off the wind) and rolled in some staysail. I wouldn't have wanted a single reefed main and staysail up.

That said, I don't believe that Anna was over canvassed beating with one reef and the staysail up in 12 to 20 knots of apparent wind with squalls around (as I interpret his account). Nor do I find it inappropriate that they were on autopilot and in the wheel house.

It is so easy to be the Monday morning quarterback -- I really hesitate. This is just one point of view:

1) We wouldn't have left in these conditions unless for some odd reason we had to. My wife is an atmospheric scientist so we have excellent weather information and analysis. She (we) reviewed the data that we would have had before this trip and I base my comment on this review. Of course, I realize that it is easy for me to make this judgment here and now. This situation was different from the front we left Canada on. Our situation then was more "stable" in a way and we knew we were in for a lot of wind, so we were ready for it. Even with the much lower general wind speeds, I would describe this situation as more "unstable" or perhaps uncertain than ours was.

2) It is impossible to say how we would have reacted to the sky conditions at the time, but assuming that they were same as they had been for the last 24 hours, I might have left the boat in single reef/staysail/autopilot. The Anna folks mentioned that they were "wary." Maybe, we would have done something different. Maybe I would have been in the cockpit, maybe not. Maybe we would have been hand steering. Maybe we would have used the radar to avoid the core of the squall. Maybe we ... well, this is just too speculative for me to form an opinion.

So, assuming that we had stayed set up the way they were:

3) We focus on TRUE wind speed on our catamaran, not apparent, and set our sails based on this and what we expect it to be. This isn't to say that we are unaware of the effect of our boat speed on the wind, which for us has been eye popping with the A55 versus any mono-hull that I have sailed. In the Anna case, they were beating so the true wind was less than the apparent. When the wind gusted and went abeam, however, in our A55 anyway, the boat would have accelerated and the true wind would have been well aft of the beam. In our boat, the true wind would have read higher than the apparent wind, so they were probably already seeing higher winds than the 30 knots that made them jump into the cockpit.

4) Given the above, my first move, before I even left the pilot house, would have been to knock the autopilot down 30 to 40 degrees (three or four pushes of a button). In these specific circumstances with our boat -- e.g. with my sails flattened for beating but the wind coming abeam and increasing -- I would not head up into a squall; I would bear away.

5) Then, I would have eased the main sheet.

6) If was not alone and depending on how the boat was riding, I would take the helm (if my wife was with me, she would have taken it) and the other person would then start cleaning up -- first a reef (or two), then shorten the staysail.

I really love boats, any boats -- power, mono, ship, cats, sail, oars, ice, kayak -- they all have something to offer. The Atlantic 55 was a terrific choice for our family. My wife and I (we sailed about 58,000 miles together during a wandering circumnavigation, plus some, in the early 1980s) are converts to catamarans for our cruising lifestyle. We love the stable platform. In the case of the A55, we love the speed, the space, the forward cockpit, and the pilot house/living room among many other things.

There are characteristics which we don't like too: the A55 has appendages to catch things on (two dagger boards, two sail drives and two rudders). We caught three fishing nets/lines during our one year. I realize that some mono-hulls do too, but they only have one hull to worry about and we have two .

Would I go around Cape Horn in a catamaran (as we did in 1981)? Yes. Would I go into the ice with one (in 1984, we went into ice at over 80 degrees north)? I am not so sure about that -- I would be worried about ice jamming between the hulls.

I have a lot to learn about multi-hulls, but for us, for our long-distance sailing, we won't be going back to a monohull. The Anna Story is a wonderful reminder for me; something to keep me on edge if I ever become complacent.

I am so happy that they were rescued safely and in such a short time. I have spent almost as much time thinking about what they did after they flipped as I have about the cause of it. Lots of lessons learned there too.

Sorry about the long post. Blame Evans and Tom for drawing me in -- I have found their deep experience and thoughtful comments fascinating to read.
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Old 20-08-2010, 10:45   #242
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Some of you may find the Multihull section of Offshore Cruising by the Dashews applicable to this discussion.

A small snippet:

"A week later we were beating up the coast toward Ensenada in the teeth of a northwesterly gale, common at that time of year. The crew was a bit under the weather, but, shortened down comfortably, Intermezzo was driving herself easily uphill. Occasionally a squall would bring gusts in the low 50s, and she would be momentarily overpowered. By this time I was worn out and had to let her fend for herself. I never could have done that in a multihull.

As a result of these two experiences we kept Intermezzo. I came to realize very quickly that in spite of all my previous experience in multihulls, if we were to go offshore in one I would have to stay continually alert and could not afford a mistake like turning the corner of Cedros Island."
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Old 20-08-2010, 10:55   #243
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The other part of managing the energy in a multi hull is the load. If its carrying to much in the wrong places the energy cant be unloaded efficiently.Not saying this had anything to do with this capsize just another factor.
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Old 20-08-2010, 11:00   #244
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The thing that would continue to worry me if I still had a cat, any cat, is that the weather is inherently unpredictable. When we sailed down to Colombia from the US we spent 6 days offshore, and we were nearly constantly dodging huge powerful thunderstorms. This is rather typical late spring weather down there, and in the black of the night we would be hit by ferocious blasts and wind direction changes that were completely unexpected. Several times, on that single passage, the on-watch person had to call up the off-watch person to suddenly drop, reef, or reset sail. Once we were caught completely aback with all sail set as we were running off, and then the wind switched to the nose and came in at 30. Even if you know the storm is coming you can't tell if it is packing the typical 30-40 knot gusts, or the less typical 60-knot gusts. I don't care how good your seamanship is, short of taking down all sail, it would be very hard to have the proper amount of canvas up at all times and to be vigilant enough to always be prepared for the unusual gust.
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Old 20-08-2010, 12:11   #245
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Originally Posted by estarzinger View Post
I am still trying to juggle the concept and safety trade-offs of a fuse (or other type of automatic release). It seems to me that perhaps the best technical answer would be to have a fuse on the clew of the mainsail (connection between clew and outhaul).

That would not cause all the potential safety factors that a fuse on the sheet/boom causes (possibly hitting a person or hitting that side stay). These sails will certainly have full battens so you will probably not even have a madly flapping sail - might just have a few broken battens to replace.

The clew fuse would only work with a full hoist mainsail, so you would probably also have to fuse the attachment points for at least the first reef clew (i presume these sails use clew reefing blocks and the lashing/attachment of that block to the sail could easily be a fuse).
Interesting idea.

I've blown the clew out of the the main and had a shackle break on the boom. Kinda simulating some different release methods. Both take the power off very quickly and with a full battened sail you don't get damaging flogging. And, IME the battens are very durable so I don't think you'd need to worry all that much about busting them. The recovery from a blown clew/reef is to tuck in the next reef which is typically quick, easy and familiar. Recovery from a lost sheet attachment is to get a preventer on the boom to stabilize it and then reattach the main sheet which is slow, distracting and doesn't typically get practiced. And the falling down rig as a safety feature doesn't make me happy at all. We recently had a fatality here when a rig was dropped and I know of another very bad injury as a result of another rig going down and have heard several pretty scary near miss stories... Of the ideas on this I've heard lately (sheet release, boom/mainsheet attachment fuse, clew/reef fuse) I think the clew/reef release has some potential advantages -- it dumps the power faster than the sheet release and unlike the other ways presents little danger to people standing in the way of the boom.

I'm not sure how easy the analysis of the clew loading would be -- sheet tension can be very high to weather in cats for instance. And I'd want to test a whole lot of fuses to be confident that they'd break consistently. I've noticed that different batches of spectra line from the same manufacturer seem to have noticeably different UV, wear and I suspect strength differences... Thoughts?

Tom
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Old 20-08-2010, 14:36   #246
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Quote:
Originally Posted by estarzinger View Post




.................1
  • Where :
  • D = displacement (lbs).
  • CE = height of the center of effort above the center of gravity (C.G.) in feet.
  • SF = windspeed in MPH that the boat has to reduce sail.
  • SA = sail area in square feet.
  • B = beam between the cenerlines of the outer hulls in feet.
This formula has always bothered me due to the number used for CE. This number is found by measuring the distance from the CG to the CE. The higher the CE, the lower the SF will be and conversely, as the CE is lowered the SF becomes greater. So far so good, but if the CG is raised, the number used for CE is lowered and the SF is raised. This does not make sense to me since as the center of gravity is raised, the boat should become less stable, not more stable. It seems to me the formula could be made more accurate by measuring CE from the waterline and maybe adding CG above waterline to the number. That way as CG is raised, the number for CE is rased as well.

Does anyone else see this or should I just stick to things I may know something about?

Mike
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Old 20-08-2010, 16:30   #247
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An update on the capsized cat Anna appears in today's 'Lectronic Latitude:

* * *

Flipped Cat Anna Washes Up on Tonga

August 20, 2010 South Pacific

(Click on the
photo to enlarge it.)
There are many false rumors flying around Tonga in relation to the capsizing of Anna.
2010 Scott Stolnitz

"Anna, the Atlantic 57 catamaran owned by Kelly Wright of Santa Fe, New Mexico, that flipped 125 miles from Niue in the South Pacific the first weekend in August, somehow managed to make her way unscathed through the East Reef passage of the outer reef at Vava'u, Tonga, then washed up against an island and was badly damaged," report Scott and Cindy Stolnitz of the Marina del Rey-based Switch 51 cat Beach House. "She's now tied to a mooring in Neiafu, where she looks like "parallel submarines at Disneyland."

* * *

For the rest of the update, go to:

Latitude 38 - 'Lectronic Latitude

TaoJones
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Old 20-08-2010, 17:26   #248
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Originally Posted by gosstyla View Post
Some of you may find the Multihull section of Offshore Cruising by the Dashews applicable to this discussion.

A small snippet:

"A week later we were beating up the coast toward Ensenada in the teeth of a northwesterly gale, common at that time of year. The crew was a bit under the weather, but, shortened down comfortably, Intermezzo was driving herself easily uphill. Occasionally a squall would bring gusts in the low 50s, and she would be momentarily overpowered. By this time I was worn out and had to let her fend for herself. I never could have done that in a multihull.

As a result of these two experiences we kept Intermezzo. I came to realize very quickly that in spite of all my previous experience in multihulls, if we were to go offshore in one I would have to stay continually alert and could not afford a mistake like turning the corner of Cedros Island."
Could someone please explain this statement. It seems to fly in the face of fact.
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Old 20-08-2010, 17:57   #249
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Ithink the just is that as performce goes up the level of energy used also increases. This can become exhausting paying close attention and being exhausted Is more exhausting. The mire forgiving a boat the chances fir rest increase. Don't thunk that is why this boat flipped though.I can really screw up on my Peterson in the f27 I really really can screw up
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Old 20-08-2010, 19:29   #250
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There's no argument that sleek hull design and dagger boards increase performance. Most people interested in cruising catamarans pour over these numbers, they even discuss and argue them. If the need for speed trumps conservative sailing, we will see a photo like the one above every now and then, as cats with boards have been known to occasionally trip over them, when the crew is less than alert.

I prescribe to the safety and comfort school. Admittedly, that's a personal choice.
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Old 20-08-2010, 20:24   #251
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This formula has always bothered me due to the number used for CE. This number is found by measuring the distance from the CG to the CE. The higher the CE, the lower the SF will be and conversely, as the CE is lowered the SF becomes greater. So far so good, but if the CG is raised, the number used for CE is lowered and the SF is raised. This does not make sense to me since as the center of gravity is raised, the boat should become less stable, not more stable. It seems to me the formula could be made more accurate by measuring CE from the waterline and maybe adding CG above waterline to the number. That way as CG is raised, the number for CE is rased as well.

Does anyone else see this or should I just stick to things I may know something about?

Mike
Yes I think the qualification of what CE represents is incorrect. It should be the distance between the CE and CLR which determines the length of the lever arm.
See....

Other multi designers also appear to take this view.
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Old 20-08-2010, 20:26   #252
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I don't have a cat (ha) in this fight but there is a theme about the boat and the sailor that I am confused about.

"Most" boats can have too much sail up for given conditions. In reading 250 posts about this I still fall back on the indications of the weather.

Understanding, or predicting/calculating, what your particular boat (mono or multi) can carry sail-wise for given conditions is part and parcel of learning your boat.

Exploding weak links, when the sail is most powered, seems a pretty drastic and unpredictable method.

What happened to reefing early?

I recently sailed on a boat with in mast furling for the first time (many thanks skipper, you know who you are).

Argue about "real sailors" all you want. The ability to shorten sail, almost immediately and effortlessly (with the electric winch), is an amazing feature. It makes looking at the dark horizon and debating whether to reef a no brainer in my opinion.

"Let's get 50% of the sail (main and jib) in until we see what these squalls are going to do."

On a 42'+ catamaran, where a lot of money has already been spent, that will be sailed short handed by a couple, I think this is a great feature and one I will be looking for.

Once the sails are short enough, sailing unattended becomes a better prospect.

I understand the difficulties based on the sail shapes carried by most cats but when you are reefing there is plenty of power in the wind and sail shape actually becomes less important for efficiency. Also sail shape/type may have to be sacrificed or reconsidered when considering safety/performance trade offs. Once again trade offs are a way of life in almost any human endeavor.

Please note I am not talking about penetrating big weather systems, which should be known about with today's weather gear and information. I am talking about penetrating dispersed thunderstorms as we have all too frequently in the tropics.

I'll go back to sleep now...
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Old 20-08-2010, 20:38   #253
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They didn't reef early in fact they. Errr being aggresive as they wanted to make time. There it is they wanted needed to make time weren't giving up performance for time. That was the choice I hope they understood the performance bs risk idea. I'm good with their being okay I am confident they made bad choices for what ever reason.
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Old 20-08-2010, 20:51   #254
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If one goes down the path of fuseable links, then the question arises, is the cure more dangerous than the illness?
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Old 21-08-2010, 05:00   #255
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Quote:
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the three options: (1) letting the clew blow, (2) letting the boom fly, and (3) capsizing. #1 seems to me to be the least worst. I don't see any other options - am I missing one?
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I have huge concerns with fusable type systems. Do you want to be anywhere near 1000 sq ft of uncontrolled sail, .
You two youngsters just don't listen to moi!

With my Emergency Release Button post earlier I suggested putting it to a product engineer. The reason for that is one can say what they want and don't want. You tell the engineer you don't want 1,000 ft uncontrolled sail, or 'blowing' clews etc.

What I think the fuse needs to be is some type of controlled release system, maybe highly engineered. So when the button is pressed the [whatever] is released a certain amount. Then more if the mechanism decides more needs to be released, quickly but controllably.

I would have thought a winch run out 5 feet per second then half second pauses as the pressure is recalculated then release again; till a programmed safe pressure is achieved.

I don't know, but surely an expert, properly instructed can come up with a controlled safety release that doesnt need just 'blowing' sheets or clews etc.



Their use may well be good on monohulls where the mainsheet is forward of the helm. The Emergency Release button is on the helm and in a broach/squall etc hitting it lets the sheet out at a controlled rate.

How about a Button in the nav station? A short handed crew throwen out of bed can just hit the button! No need to get spray in the face.





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