Let's think about drag, too. If steering authority was a single consideration in rudder design, then we would see rudders with huge chord lengths. On larger boats, with the expense of creating a foil shape that has the right thickness to length ratio, the prevailing design type IS a thin-ish barn door dragging behind the boat. Different amounts of material ahead of- and behind the center of rotation of the rudder head affect the effort needed to control the rudder, but drag is not taken into account or it is ignored in favor of counteracting weather helm and not allowing the pressures on the rig to overcome the steering authority. These rudders cause huge wakes and create a lot of drag.
So maybe adding surface area alone is not the best rudder design, and I am now speaking of the trailer sailers we all drag behind our vehicles. Because of the relatively diminuative size of our boats and rigs, can a rudder be designed that is efficient enough to have steering authority, and minimize drag? We often find that the stock rudder found on production boats under 27 feet LOA are at best a compromise, and sometimes even laughable. The owners of such craft sail for years with rudders whose drag or lack of steering authority would be immediately corrected if their automobiles display such poor handling characteristics. Belive me when I say that these crude designs are featured on many sailboat brands, this being the rule instead of the occasional exception. I see a lot of rudders, by the way.
So if you could start over and build a rudder from scratch, use a proven airfoil shape, situate the design in relation the vertical pivot centerline to reduce tiller effort, what would it look like?
