Since the advent of the Coronado series of over the horizon blue water
cruisers boats such as Donald Street's Iolare and his books on blue water
vessels have fallen out of favor. However out of favor, there's timeless
principles contained within his books.
One concern is rudder efficiency. If the bottom of the leading edge of the
rudder is located more forward than the top he claims it is the most
efficient. The vertical rudder is less efficient and the rudder where the
bottom leading edge trails the top is the least efficient. How is this
efficiency measured/defined? How does the cant (angle) affect the
efficiency?

Myron