On Fri, Mar 4, 2011 at 12:36 PM, Gardner Pomper <gardner@networknow.org> wrote:
I have been trying to figure it out, but I just don't understand. Why would this design have lee helm? Because the rudders are further apart? I thought the further the better. Now I am just confused! x-(
My impression was that the drag from the ww hull would give the harry's an overall weather helm, which you had to counteract by moving the rudders as far "aft" as possible.Or is it because of the ballestron rig?How do you figure out where to put the rudders?- Gardner
MIkes reply is correct.
How do I figure out where to put the rudders? Experience, I suppose. 25% of the length seems to work. I always used to think that if the aft one was aft of the coe, plus an allowance for the windward hull causing weather helm, then the rudders could be balanced by locking and lifting the front rudder. However, on El it is a long way aft of coe, the boat steers ok with either or both rudders and whether the ww hull flies or not. On the other, bigger harrys I rarely got round to seeing what happens. They steered fine with both rudders. RB steers with one on a reach or a run (didn't try it upwind). I suspect that once you are up to speed you have a lot more latitude with foil location than when you are going slow. This could be to do with the long, shallow, rockerless hulls.
Where the rudders can make a difference is shunting, but if you shunt by luffing first (rather than sailing from reach to reach), and observe the flow over the sails and the rudders to make sure neither stalls, then I suspect it makes little difference where or how many rudders you have down. I will do some experiments when the new Sol goes in the water. Lw hull infusion on Monday. Launching next month, same as it has been since November.
rob
How do I figure out where to put the rudders? Experience, I suppose. 25% of the length seems to work. I always used to think that if the aft one was aft of the coe, plus an allowance for the windward hull causing weather helm, then the rudders could be balanced by locking and lifting the front rudder. However, on El it is a long way aft of coe, the boat steers ok with either or both rudders and whether the ww hull flies or not. On the other, bigger harrys I rarely got round to seeing what happens. They steered fine with both rudders. RB steers with one on a reach or a run (didn't try it upwind). I suspect that once you are up to speed you have a lot more latitude with foil location than when you are going slow. This could be to do with the long, shallow, rockerless hulls.
Where the rudders can make a difference is shunting, but if you shunt by luffing first (rather than sailing from reach to reach), and observe the flow over the sails and the rudders to make sure neither stalls, then I suspect it makes little difference where or how many rudders you have down. I will do some experiments when the new Sol goes in the water. Lw hull infusion on Monday. Launching next month, same as it has been since November.
rob
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