Building a new ruder for Footprints resulted in much easier helming, a big reduction in weather helm and I am sure more speed. The changes made to the rudder were a reduction in chord length by 10cm to provide a higher aspect blade, a doubling in the balance area forward in the bottom section of the rudder to reduce helm loads, and proper profiling to an NACA foil. Total chord thickness is only 7cm. Draft of the rudder is one meter, chord width of 40cm at the unbalanced section and I think 55cm in the balanced area.

Certainly profiling a rudder to a proper foil shape will give significant improvements in rudder effective, but if you were to go to a chord thickness of 14cm I would think that you could introduce a lot of drag.

Paul's La Chica had a dramatic improvement in performance by changing his rudder. LC now sails faster to windward than Zebedee despite a lower sail to weight ratio and a propeller. Zebedee's rudder is cambered but is only about 5cm thick for about 100 cm from leading to trailing edges.(the shoal draft version of the Benford 34 sailing dory as described in Voyaging on a small income).  Does anyone think that increasing the thickness to 14 cm with the appropriate camber would make a difference? It occurs to me that this modification might be fairly straightforward to do, and the result would be measurable when sailing with LC