[upwind,] The reduced load on the centerboard now falls on the rudder as an increase in load. Therefore increase the rudder area, rudder balanced, in direct proportion to the increased load it now carries. Now the centerboard is happy and so is the rudder and lee helm with the spinnaker up has been solved...No more radical mast rake required and no more overloaded rudders with a hair trigger ready to stall sailing to windward.
Wait a minute Bill...you moved the board forward to counter lee helm induced by the spinnaker and agree that the rudder loading is increased upwind. To that point you can make the daggerboard smaller but the rudder bigger. Somehow you conclude that the forward daggerboard placement also helps prevent rudder stalling upwind. But you just said the rudder loads are higher upwind now as a result of the daggerboard placement - did I miss something?
Supose we took an I20 and moved the boards forward as you prescribe (this boat runs very little mast rake and it's forward beam is very far forward on the boat). This would only make the windward rudder stalling problem more severe.
