Re: Why does Tanzer 22 turn faster than Morgan 22?
Messing with a rudder is typically a bad idea without a lot of engineering behind it. Besides the foil shape aspect, you also have to deal with balance (both CE on the boat, and a balanced rudder), attachment issues, hull strength issues, ect.
Typically a deeper, thinner, narrow foil will be best, but there are a lot of trade off decisions that need to be made. For instance a thinner foil is faster, but more prone to stalling, while a narrower rudder has less wetted surface, but has less bite.