From the steering oars employed by the earliest sailing vessels rudders have evolved into the centrally mounted foils we see today.
On a production boat you don’t usually have the option of specifying the rudder configuration – you get what you’re given – but the design of the rudder will certainly affect the suitability of a particular boat for your purposes.
Whether the boat is for competitive racing or for blue water cruising, the need to sail efficiently is a given and the primary aim of the rudder’s designer will always be to minimise wetted surface, minimise frontal area, and provide the most turning efficiency with the minimum drag.
A rudder is subjected to tremendous forces from the pressure of the water rushing past it – the designer has to get his sums right when deciding how to support the foil in this environment and then the builder has to be meticulous in implementing the design.
Where the requirements of the racer and the blue water cruiser will differ is in how much protection they demand for the rudder at the expense of speed and efficiency, and what priority they give to taking the ground without damage and to avoiding the snagging of lines.
At one end of the spectrum is the unsupported, balanced, skinny foil of the out and out racer; at the other end of the spectrum is the barn door bolted onto the aft end of a full keel. In between are full and partial skeg mounted rudders and transom hung rudders. Choose carefully.