Proa Questions: Atlantic vs Pacific

Discussion in 'Multihulls' started by Inquisitor, Jun 22, 2010.

  1. KSONeill
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    KSONeill Junior Member

    This niggled at the back of my mind this morning, until I went back and searched up this message:

    http://groups.yahoo.com/group/proa_file/message/22545

    which says in part:

    1999 PRAO DE CAMPING COTIER
    Camp cruiser, rigged as a shooner, of 10m; can be desassembled for trailering; it is defined as "biamphidrome" ( it sails as a Pacific Proa in light winds, and Atlantic proa in strong winds). Designed and built by Denis Kergomar at Ballaruc les bains, France.

    This is from a web site in French by Vincent Besin, translated for us by Laurent Coquilleau. So, what you're describing is a "biamphidrome". Sadly, googling on the term only finds two hits, the original page and the translation above. Still, it appears to have been a real boat. Well done for thinking of it yourself.

    Kevin
     
  2. KSONeill
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    KSONeill Junior Member

    I guess we have to define things more carefully so we're all using the same terms. "Outrigger" to me means a boat that's paddled, an OC-N for N=1, 2, 4 or 6, or a tacking boat. Google on "tacking outrigger", you'll get lots of hits for single outrigger sailboats that tack rather than shunt, and so are not called "proas". Flaquita is a nice daysailor example in Austin, Tx.

    Regarding Atlantic proa capsizes, Nuget on Lady Godiva/Godiva Chocolatier/Saint Marc II/Funky But Chic (all the same boat) was capsized by a rogue wave, according to his accounts, not by going aback. Merlin/Azulao II/Fleury Michon II (all the same boat) and Eterna Royal Quartz both were damaged in collision. Rosiere lost a stay and folded up. Eka Grata went aground and was destroyed.

    I don't think there's a real history of lots of Atlantic proas going aback and flipping. If there is, I've never seen it.

    Regarding Pacific proas going aback, it's too broad a question, and my contention that they'll flip more easily is really not justified; I should say "flip or break something or drop the rig or something like that". Pacific proas can be any of several types. A traditional Micronesian boat like this:

    http://upload.wikimedia.org/wikipedia/commons/b/b9/Proa1.jpg

    if sent aback will have the rig fall down. If the rig didn't fall the ama would sink, it's a solid log.

    A more modern proa of a similar type like Gary Dierking's designs:

    http://homepages.paradise.net.nz/garyd/t2.html

    has more flotation in the ama, and has a fancy "pogo stick" which allows the rig to fall to a controlled 45 degrees or so, then pop back up when you scull the boat around again. I built a similar but bigger rig. The pogo stick will save you, but in a lot of wind it's a great strain on the boat. I came to think it was better to just let the rig fall down flat and then sort things out.

    Russ Brown's boats, like this one:

    http://www.wingo.com/proa/brown/jzero78.html

    are not at all forgiving of going aback. Mark Balogh, who crewed on the boat, said there:

    "We never really got caught hard aback. The mast wasn't stayed very strongly from the lee side so that was one thing you really tried to avoid. "

    I think pretty clearly the rig would fall down and stuff would break in any sort of wind.

    All these are more or less by design. If the rig doesn't fall down you'll either break a beam or capsize the boat. The amas are low volume; my boat has about as high a ratio of ama volume to main hull volume and sail area as you'll ever see on a pac proa, and if I go aback in a lot of wind the boat will go over pretty quickly. For one thing, if the rig doesn't fall down it's pinned against the stays, you start moving and the aft CE is trying to head the boat up. But the ama drag is trying to head the boat down. Very stable, rather hard to steer either up or down. Very powered up. Very little diagonal stability. Over you go.

    So sure, there's some ama volume to help you. But the beams often aren't intended to take much stress in that direction, look at Russ Brown's beams. The ama volume is small in relation to the rig size. So it seems to me that an Atlantic proa aback and flying a hull would have a better chance to recover than a Pacific proa aback and sinking an ama. But that's a generalization, there are lots of different rigs, beam designs, ama volumes, many variables.

    Rob's WTW designs are intended to be foolproof, I think, and so probably handle going aback better than any others. No stays to pin the rig, for one thing. You might still run the risk of a diagonal capsize if you got moving fast when aback, but there's no reason to, since the rig isn't pinned.

    Kevin
     
  3. Alex.A
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    Alex.A Senior Member

    Biamphidrome....Sounds cool - BUT how easy could it be to do it quickly or at sea?
    How about 2 smaller ama's that slide across? The main hull would always have one tucked up against it.... but then the rig would have to be in the main hull.
    And then what do you do with the deck area.... ? :D
     
  4. KSONeill
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    KSONeill Junior Member

    Thank you!

    I'm sold on the schooner rig. I'd use it on any size boat. Des Jours Meilleurs is a much bigger boat with a similar rig, that's a great looking boat.

    The COE is lower. That's good in all but light air. We had a race recently, with the somewhat aggrandized title of Texas Proa Championships:

    http://wikiproa.pbworks.com/Texas-Proa-Championships-2009-Race-Report

    The white boat has a much higher AR than I do, clearly. In under ten knots I could actually keep up with him to windward (!!), and I shunt faster than he does, but he killed me downwind. I think in light air you want to get some area up high, there's more wind up there. And clearly once he gets his sail shape better sorted he'll beat me up to windward too, higher AR is better.

    Still, I have a 6' leeboard to a Speer proa profile, and the boat goes to windward quite well, I'm very happy with it on that count. I wish I could go wing and wing downwind, but I can't see a good way to manage it.

    The two big advantages of the schooner are: 1) the ability to control the CE of the sails when you're sailing out of a shunt. The rudders aren't working yet, it's a big advantage to be able to sheet the front sail first and get moving, then bring the aft sail on as your rudder powers up. Big, big advantage. The boat is very controllable now, I don't worry about sailing in a crowd or about pinching up too high or shunting in a lot of wind, it's all very easy. And 2) the rig is low, so the mass of the rig up high is reduced, so the boat pitches far less. The ends are very fine, of course, they're both bows, so the boat could be very pitchy. I think that's why you see schooners on so many of the French Atlantic proas. My boat is less pitchy than a H16, which has to be because of the lower rig.

    Disadvantages; it's two of everything to buy and rig, and two sheets to mess with, or three if I have the jib up. Clearly one person can't steer and have three sheets in his hand, so I cleat stuff off and drive the boat more than I was comfortable with from beachcat sailing. It is nice in a lot of wind to have one sheet on a big sail, rather than three on three smaller sails. But I manage. The tops of the masts are carbon windsurfer masts and the top 8' are unstayed, so they flex off in a lot of wind, that's a built in safety feature I didn't really plan for but will be happy to take the credit. I reef both mains at about 17 or 18 knots when going to windward, but keep the jib up. Going to windward in over 20 knots I hold the sheet of the front main; if I let it off the boat comes down fine but still keeps moving. Very different from sailing a beachcat, though.

    Kevin
     
  5. KSONeill
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    KSONeill Junior Member

    Just tack or jibe. How bad could it be? Sailing in light air and you have to come about, if it's still light you shunt, if it's picking up and you want the heavy ama to windward you jibe. If it stays heavy you shunt, if it dies you jibe. Assuming the boat's sorted out for both modes, that is.

    That's, uh... Crossbow? Or Crossbow II? One of the speedsailing boats. Dave Culp has a good page on them somewhere, google around and you'll find it. I think it sounds much, much slower and more dangerous than just shunting the boat, for anything intended to be a practical cruiser. Shunting is easy and fast, you don't have to avoid it.

    Kevin
     
  6. cavalier mk2
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    cavalier mk2 Senior Member

    The atlantic proas I was thinking of were Dick Newick's Cheers before he put the pod on and the one he did for Rory. To be safe it seems like a good idea to build proas that can handle anything. There are many areas that get unbelievable wind shifts so a cruising boat should be able to handle anything, because everything usually happens!
     
  7. KSONeill
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    KSONeill Junior Member

    Rob's freestanding masts and Newick's Atlantic proas with freestanding masts can't really be caught hard aback like a stayed Pacific proa can. I guess in that way they're safer, sure.

    The thing is, though, lots of monohulls would be in trouble if you were suddenly tacked or jibed without warning, because of backstays or canting keels or whatever. No one seems to think they're a menace because of that. So if a boat with backstays could lose the rig from an unexpected jibe, and a proa could lose the rig from an unexpected jibe, which is what going aback is, then what's the difference?

    Kevin
     
  8. cavalier mk2
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    cavalier mk2 Senior Member

    Not much difference for racing or the trade winds, for cruising it is good seamanship to have the rig strong enough to cope with the wind from either direction, though it only needs to be maximized for one. Just a personal preference, around land masses the wind can do unexpected things and I'd rather be sailing than dragging the rig back onboard. It is hard to imagine that proas will ever be standardized, like many things there is not one "best" approach to the concept.
     
  9. Alex.A
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    Alex.A Senior Member

    Sorry to be cross purpose here - but... for a tacking outrigger - how eqaul would the hulls have to be for the good tack/bad tack to be lessened? Would it be worth it or are we talking catamaran?
    Asymetric catamaran - how asymetric can it go?
     
  10. terhohalme
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    terhohalme BEng Boat Technology

    Something like this?
     

    Attached Files:

  11. Alex.A
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    Alex.A Senior Member

    Yes - like your styling! Why the schooner rig tho? I liked ping-pong's more....:D
     
  12. terhohalme
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    terhohalme BEng Boat Technology

    When the free standing masts are located at beams, the structure is easier to engineer light and strong. I modelled this to Rob's customer few years ago (before global money mess) and as I remember, two mast was asked.
     
  13. KSONeill
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    KSONeill Junior Member

    It also lets you control where the CE is right after the shunt, which gives you better control at low speeds and lets you get by with smaller rudders. I have a sailing buddy with an A-cat rig on his proa, who has also sailed on my schooner rigged proa. Having sailed them both for a few years, he said if he had a bigger boat he would use a schooner rig.

    K O'N
     
  14. ThomD
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    ThomD Senior Member

    "I don't think there's a real history of lots of Atlantic proas going aback and flipping. If there is, I've never seen it."

    There isn't a real history of APs for the most part. Cheers was caught aback and the problem was addressed with a pod. Russ's pacific proas have taken that to the point where they are self righting. If I recall Mark was on the early proa? Russ has been way out there in both the Atlantic and the Pacific, and I have his father on tape saying the boat is self-righting, though Russ doesn't like to talk it up much. This is dynamically self-righting in that it pops back up, and keeps on going, as opposed to needing to do a whole bunch of stuff as on the G32, for instance.

    The problem with Russ' boat is that it works, but it doesn't really seem to be a solution to any problem other than the desire to sail a pacific proa that is very easy on the eyes. It is a particular individual's boat that works for him. Not sure it gets anyone without the emotional investment anywhere. And I say that with decades of admiration.

    The harry proa really seems like the only game that ads up, and it comes with several strictures, and complexities. Also, it looks terribly wet in the video I have seen. Getting the stearing right seems terribly complex. And you need a free standing carbon mast. I have plans and will probably build one if I ever get seriously close to a cheap mast.


    I don't see any reason for atlantic proas. Amas just don't add that much to weight, cost, or time budgets, and two of them have massive advantages. The atlantic idea has been around for a long time with not a lot of success. Cheers being the main exception. Hard to say what would have happened if a similar sized boat had had two light weight amas, and one stayed spar, and put the weight of the two free standing wood spars into the new ama. An equally radical idea could have been plywood folded amas of lightish construction. They might not have made it, but them the proa was hardly a certainty either. The rig could have been much more efficient ona tri, battened rotating, etc.... Want to handicap that race run a 100 times?
     

  15. KSONeill
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    KSONeill Junior Member

    There have been more Atlantic proas built and sailing than you would think. I collected some images of some Newick and French proas and put them on three pages, starting here:

    http://wikiproa.pbworks.com/Images from the Proa_file archives

    I count ten or eleven big Atlantic proas. Just because we don't see much about something on the internet doesn't mean it's not being done, or that it doesn't work. Someone built those boats, one after the other, which means to me that they had some idea that they worked.

    K O'N
     
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