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Re: Off center fins and water flow
By:Mike Spence
Date: 7/9/1998, 5:56 pm
In Response To: Re: Off center fins and water flow (NPenney)

Did anybody answer Dave's original question? I'm curious about whether or not his suspicion has any validity.

Here's his question:

> This is my question. I suspect but do not know that water does
> not flow front to back under the hull of a kayak. If you just plop
> boat down into the water the displaced water would flow at a perpendicular
> angle to boats longitudinal axis - from midline to sides. I imagine
> that as speed increases the flow tends to straighten out but is never
> exactly front to back. The result of this for an off center fin that
> is under hull but not on midline would be that for any given speed
> there would be an angle of fin/skeg that would not apply corrective
> pressure because it would be in line with true direction of water
> flow. Conversely, a fin that ran parallel to boats direction of travel
> would have greater pressure on inboard side of fin and this would
> try and turn boat even though fin was straight. The least amount of
> drag would be at some angle to centerline, with the exact angle depending
> on the boats velocity. For best effect (least drag, most corrective
> action), I wonder if skeg should be angled for maximum performance
> at a specific speed (like 3 knots). On another list, I was also informed
> that current designs on sailboats and so on have an endplate at bottom
> of rudder or what have you to increase efficiency, presumably because
> this prevents water from "cheating" by sliding under rudder
> from the high pressure to the low pressure side. This simple idea
> adding a trim tab is getting complicated, although perhaps the impact
> of all these variables is negligible in reality.

>Dave

Mike Spence

Messages In This Thread

Mayday Mayday! boat goes left
David Walker -- 7/6/1998, 9:17 pm
Re: Try another paddler
Jay Babina -- 7/7/1998, 2:32 pm
Re: Mayday Mayday! boat goes left
Mark Kanzler -- 7/7/1998, 11:51 am
Re: rudders
NPenney -- 7/8/1998, 8:17 am
Re: Aspect ratio.
Mark Kanzler -- 7/8/1998, 11:21 am
Re: Aspect ratio.
NPenney -- 7/8/1998, 2:34 pm
Re: Aspect ratio.
Nick Schade -- 7/8/1998, 3:17 pm
Re: Higher Aspect ratio = No Steering
NPenney -- 7/9/1998, 7:49 am
Re: Higher Aspect ratio = No Steering
Mark Kanzler -- 7/9/1998, 10:38 am
Re: Higher Aspect ratio = No Steering
NPenney -- 7/9/1998, 11:50 am
Re: Old Textbooks, etc.
Mark Kanzler -- 7/11/1998, 12:52 am
Re: Old Textbooks, etc.
NPenney -- 7/10/1998, 2:53 pm
Re: Here's a sketch of one possible solution (as described in prev post)
Mark Kanzler -- 7/8/1998, 12:41 am
Image link still not working.
Mike Spence -- 7/7/1998, 1:28 pm
Re: Image link still not working. (Sorry)
Mark Kanzler -- 7/7/1998, 1:56 pm
Re: Image working.(?)
Mark Kanzler -- 7/8/1998, 1:26 am
Not yet. - Don't despair!
Mike Spence -- 7/8/1998, 1:19 pm
Re: Not yet. - Don't despair!
Mark Kanzler -- 7/8/1998, 2:18 pm
Re: Here it is! (Satisfaction Guaranteed)
Mark Kanzler -- 7/8/1998, 10:23 pm
Re: Here it is! (Satisfaction Guaranteed)
David Walker -- 7/10/1998, 10:28 am
Re: Surfbard skegs.
Mark Kanzler -- 7/10/1998, 11:58 am
Re: Surfbard skegs.
David Walker -- 7/10/1998, 1:49 pm
Re: Surfbard skegs.
David Walker -- 7/10/1998, 5:30 pm
Re: Surfbard skegs.
Mark Kanzler -- 7/12/1998, 11:08 am
Re: Surfbard skegs.
Paul Jacobson -- 7/12/1998, 7:18 pm
Re: Surfbard skegs site (try it again please).
Mark Kanzler -- 7/10/1998, 2:50 pm
Re: Surfbard skegs site (try it again please).
Mike Spence -- 7/10/1998, 6:51 pm
Re: Here it is! (Satisfaction Guaranteed)
Nick Schade -- 7/9/1998, 4:12 pm
Re: Here it is! (Satisfaction Guaranteed)
Mark Kanzler -- 7/11/1998, 12:37 am
Re: Mayday Mayday! boat goes left
Mark Kanzler -- 7/8/1998, 12:39 am
My $0.02
CHad -- 7/7/1998, 11:29 am
P.S.
CHad -- 7/7/1998, 11:56 am
Re: P.S.
Guy Wright -- 7/7/1998, 1:46 pm
Me Too!
Shawn Baker -- 7/8/1998, 11:01 am
Re: Mayday Mayday! boat goes left
NPenney -- 7/7/1998, 7:33 am
how I solved mine.
R. N. Sabolevsky -- 7/6/1998, 11:56 pm
Re: Mayday Mayday! boat goes left
Duane Strosaker -- 7/6/1998, 11:38 pm
Re: Mayday Mayday! boat goes left
Mike Spence -- 7/7/1998, 12:11 pm
Re: Mayday Mayday! boat goes left
Paul Jacobson -- 7/6/1998, 11:20 pm
Off center fins and water flow
David Walker -- 7/8/1998, 5:28 pm
Re: Off center fins and water flow
NPenney -- 7/9/1998, 11:57 am
Re: Off center fins and water flow
Mike Spence -- 7/9/1998, 5:56 pm
Re: Off center fins and water flow
Paul Jacobson -- 7/11/1998, 2:53 am
Re: Off center fins and water flow
Mark Kanzler -- 7/10/1998, 11:47 am
Re: Off center fins and water flow
NPenney -- 7/10/1998, 6:22 am
Re: Skegs and water flow.
Mark Kanzler -- 7/8/1998, 6:10 pm
Re: Skegs and water flow.
David Walker -- 7/8/1998, 6:42 pm
Re: Skegs and water flow.
Mark Kanzler -- 7/8/1998, 7:07 pm
Re: Skegs and water flow.
David Walker -- 7/10/1998, 10:37 am
Re: Skeg attachment w/ silicone.
Mark Kanzler -- 7/10/1998, 11:34 am
Re: Mayday Mayday! boat goes left
Wes Boyd -- 7/6/1998, 10:36 pm