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Mayday Mayday! boat goes left
By:David Walker
Date: 7/6/1998, 9:17 pm

As indicated in my previous post, I have a new boat which is very nice in all respects except that it has a prediliction for going to the left when I want it to go straight. I believe, but am not sure, that this is due to a slight curvature in last 18 inches or so of keel. I have considered a number of options and would appreciate any input as to the merits or lunacy of any of these ideas.....or other thoughts or considerations.

Option 1 - live with it and paddle harder or with more sweep on one side. I really donít like this one.

Option 2 - Install a rudder. If I really have to but I am one of those types that is strongly predisposed to not having a rudder. I donít like the mechanical metal and wire moving part clutter of rudders.

Option 3 - a fixed rudder or fin that I would never have to think about after I put in on. I kind of like this. On Sunday, I attached to hull near stern, on one side, a piece of foam cut out into a wedge shape. I also took several pieces of 15 or so inch rope and taped them to bottom of hull at an angle such that they would hopefully tend to steer boat to right to compensate for the other leftwards tendency). This combination seemed to pretty much correct the problem (canít say yet how much either the wedge or the rope ridges contributed). What I see as an advantage to the wedge on side of hull, as opposed to a fin, is that it would never be in a position to get snapped off. If I go with this option, I would make a wooden wedge, kind of like a door jam and attach it near stern.

In thinking about all this, there are a number of things that I realize I donít know about but would like to know about. First, is there any reason why rudders tend to be tall up and down but not long front to back. My guess is that this is mostly because the rudder is more efficient the further aft it is and a long (horizontally) rudder would neccesarily have some of it more forwards, unless it projected outwards away from boat. I am wondering this vis-a-vis the efficiency of ridge lines or a long wedge type thing that would stick pretty close to the hull and would be pretty long but very short up and down. Second, would an asthetically more pleasing straight ridge /keel/skeg rather than angled ridge/ruddertake care of my problem. That is, something that just tries to add resistance to tendency of stern to rotate rather than something that actively counteracts this by pushing the other way. The straight skegs seem to work quite well for weathercocking, but in that case you are dealing with equal pressure on front and back of boat and you are only trying to equalize resistance of bow and stern to that pressure. My situation is a bit different and I worry that I might always get a fractional effect (something in between turning left and going straight, but never going totally straight). Still, this would look better and would add less drag I think. Third, if I have a fixed fin, ridge line whatever that makes boat go straight at a given speed and load (e.g., light day paddling) will it always go straight even at different speed and displacement? If not, this would be an argument for something more variable like a rudder, ugh. Fourth, do both sides of a rudder contribute about equally to the turning effect. If I put a wedge on the side of boat, I would effectively only have one side (i.e., the high pressure side). For fins, are there any rules as to how much they should angle away from line of travel for maximum efficiency (maximum effect with minimal drag).

Option Last - radical surgery. Cut away the offending last 18 inches of boat and have a kayak with a transom. Does this markedly increase drag or have any other untoward effects? I wish I had one of those naval architecture computer programs. Obviously, this is a major and irreversible step but its a possibility.

Sorry to be so long winded but there are many considerations. As I say, any input at all appreciated.

Thanks, Dave

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