Externet Posted May 4, 2009 Posted May 4, 2009 A sailboat tilts considerably with strong wind. Could a sailboat fitted with an inverted T keel, the horizontal 'wings' capable of independently adjusting pitch, force the hull to stay level ?
Martin Posted May 4, 2009 Posted May 4, 2009 A sailboat tilts considerably with strong wind. Could a sailboat fitted with an inverted T keel, the horizontal 'wings' capable of independently adjusting pitch, force the hull to stay level ? wouldn't that increase drag? if you don't like heeling over, the easy solution is a twin hull sailboat ---socalled catamaran
Sisyphus Posted May 4, 2009 Posted May 4, 2009 Possibly, but yeah, that would hugely increase drag, I'm thinking. Water, obviously, is a lot denser than air, and drag has a much bigger effect (which is why the keel can keep it moving straight in the first place, despite being much smaller than the sails). Even steering, on racing vessels, is accomplished as much as possible by shifting weight and trimming sails, because turning the rudder is like putting on the brakes. They keep level (or as level as possible, to get the most power from their sails) by redistributing weight above decks, and that works just fine. On some racing boats you'll see the whole crew out on scaffolding off the windward side. [/sisyphus reveals that he knows about sailing]
Externet Posted May 4, 2009 Author Posted May 4, 2009 (edited) Partially agree with the drag, but the question was about counteracting the tilt Partially, because the huge, huge ballast in a non-catamaran sailboat keel could be then highly reduced, which would decrease draft and consequently drag. Martin: http://www.cs.unc.edu/%7Ekeller/catamaran.jpg http://farm1.static.flickr.com/101/266091389_a41ac7525c.jpg Edited May 4, 2009 by Externet Added phrase
ishmael Posted May 5, 2009 Posted May 5, 2009 There are some experimental sailboats that have been built using a tilting keel, adjusted with a powerful hydraulic ram inside the boat. I don't think any of these have wings on the keel, but they do have a ballast bulb at the tip of the keel. It works better than a fixed keel to keep the boat upright, but is very expensive and complex, and much more prone to problems than a simple fixed keel.
J.C.MacSwell Posted May 5, 2009 Posted May 5, 2009 (edited) Partially agree with the drag, but the question was about counteracting the tilt Partially, because the huge, huge ballast in a non-catamaran sailboat keel could be then highly reduced, which would decrease draft and consequently drag. Martin: http://www.cs.unc.edu/%7Ekeller/catamaran.jpg http://farm1.static.flickr.com/101/266091389_a41ac7525c.jpg You can certainly produce lift ( force perpendicular to the flow), at the expense of drag, with an underwater appendage. If positioned and oriented properly it will counteract heel. The problem is with positioning and orienting it so that it does not produce additional leeway or excessive drag, and at the same time act at sufficient distance from the center of buoyancy or center of gravity to produce the leverage required to counteract a reasonable amount of heel for the drag the additional structure will create. Other concerns would be the stability and control of the system and the minimization of it's affect at low speed. At say, half speed while accelerating it would produce only one quarter of the counteracting of the heel. Edited May 5, 2009 by J.C.MacSwell
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