Gardner,

  The lee helm is only if you have a single rudder, the aft rudder, in the water, and the front rudder lifted.  The una rig works better in this case because its center of effort is aft of the mast, and therefore closer to that aft rudder.  Between the rudder and the hull section itself, you can balance out.  If you have an easyrig instead, the jib puts the center of effort forward enough to create a lee helm with only the aft rudder down.

  The reason to move the rudders as far aft as is reasonable is that they will work better for turning the boat.  Rudders at the ends, which would be impractical, would create a huge turning moment with relatively little force on each foil.  Rudders that are two feet from the center would really have to be manhandled to turn the boat, especially while resisting leeway, and even then they'd quickly lose their bite and become useless.

  My guess is that your splayed beam idea might be a great compromise.  Rob has no issues with the beam-mounted rudders on the smaller boats, and you'll have rudders even farther apart than he does.

        - Mike

  

Gardner Pomper 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

On Wed, Mar 2, 2011 at 9:59 PM, Rob Denney <harryproa@gmail.com> wrote:

 

All pluses for the rudders splayed beams except
1) The front one will not kick up without hitting the ww hull.  I moved mine inboard to overcome that
2) It will have lee helm if you only sail with one rudder.  Big deal, at least it will steer with 2,  I hear you say.  And I agree, but once you have sailed with one, it becomes pretty compelling, particularly as the bows lift up rather than get depressed by the drag on the rudder. 
3) Not sure about this one, but arguably there will be more side force on the front rudder, maybe making it harder to steer.

Look forward to the details.  Should be a fun competition.  I have now seen 4 harryproa entries, plus mine.  Plus I bet there will be a bunch of non harry proas as well. 

rob