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50219RE: RE: Re: [boatdesign] RE: Storm Petrel (Bolger's)

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  • nutty_boats
    Dec 5, 2013
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      What is in a word? When I was young, a knock-down was when a gust of wind pushed a boat over on its side, about 90 degrees. A capsize was when a boat was waving its keel in the air. But now it appears that people try to impress their drinking buddies by calling even less than a 90 degree knock-down a capsize. Then later other people pick up the same word usage just because the people around them are using the words in that manner. I think you and other people on this list are in the latter group.

      On narrow boats like yours, I have heard of 90 degree knock-downs from wind gusts, but I have not heard of capsizes (waving a keel upwards) except where the boat was badly top-heavy. You may want to put an aerodynamic float at the top of your mast, then it will be almost impossible to capsize the boat, even after a 90 degree knock-down.

      I once had a low, sleek boat similar to Marsh Duck, a little bit smaller, but it did not have a keel or a dagger board. In strong winds, it was the wind that caught it, I could tell because even in flat waters it was almost impossible to control. In waves where the wind varied along its length thanks to wave action, it was worse. I stopped using it precisely because it was so hard to control, and we often had strong winds. After that boat was stolen, I designed and build another boat that had a keel, and that keel made a big difference in its controlability in wind in both flat waters as well as waves. The keel that seems to have the greatest effectiveness is one from stem to stern. Because you have a daggerboard, your boat will not skitter sideways in the wind as fast as the waves, or faster like mine did, but is still sensitive to differences in the wind pressure as waves change its shape to the wind. It is these experiences that make me suspect that you biggest problems are ultimately caused by the wind.

      T. Lee.

      ---In boatdesign@yahoogroups.com, <scotdomergue@...> wrote:

      The Marsh Duck handles wind just fine, perhaps because her shape is low and sleek, combined with good sail/foil balance.  She has a dagger-board extending to about 3 feet below waterline, and a rudder extending about 16 inches below waterline.  Both are airfoil shaped.  I quite enjoy sailing her in all wind conditions.  She's quite steady sailing as long as waves aren't an issue - somewhat like a racing dinghy which is my favorite style of sailing.  With 107 square feet of sail on a light canoe, she's fast and fun, and sail needs to be reefed when winds get strong (3 reefs down to under 25 square feet currently).


      Waves aren't really a problem either, but do make for an active sail.  When running before the wind, particularly in quartering waves of a certain size (3 to 4 feet height, shorter than the boat peak to peak, waves will pick up the stern and push it; with strong winds I'll be surfing down the front of the waves.  Depending on what's happening with the bow (pushing into or riding up the wave in front), there can be some rocking side to side and tendency to turn involved.  I've experienced this a couple of times.  It's not really a problem, but it is quite active since my weight is what balances things and I need to move the rudder to maintain desired course.


      Regarding capsize:


      When sailing I generally find it easy enough to avoid capsize.  Other than doing capsize testing (intentional capsize), I've only gone over once.  That involved some squirrely currents and gusts that I wasn't expecting - all of a sudden she was over 90 degrees with sail in the water.  I dropped in, worked around the stern, pushed down on the dagger-board and was back in and sailing in a very short time (less than a minute in the water).  There wasn't even any water to speak of in the cockpit.


      On the other hand, in any long, narrow, un-ballasted, light weight boat, capsize in rough conditions is always a possibility.  Ocean rowing boats go through Hurricanes, and they capsize, but they are designed to self-right.  I wouldn't want to be inside the cabin of the Marsh Duck or an ocean rowing boat that stayed upside down!  With sail and spars in the water, the Marsh Duck would NOT self-right.  Even with sails and spars stowed below decks she'd be unlikely to self-right.  I'm quite comfortable sleeping inside in the places I anchor her, and would be fine out on open water if it wasn't too rough, but in really rough conditions capsize is a possibility, so I wouldn't hole up inside where I could be trapped upside down.



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