John Pierce has a cassette system where the rudders can be slip up and down in the casting vertically rather than pivoting. The advantage of this is that the rudder can be set partially down with good steering and no extra stain on the rudder or casting.

See: http://www.geocities.com/stealthmarine2002/t-foil.html

[Note the way the rudder can slide straight up or down within the castin--no pivoting. T-foils is a whole other issue...]

Downside is that they don't kick up. I think a system like John's but that can still kick up (as a safety feature) would be best for any sailing off the beach. I believe one of the new Farrier tris has such a system (but a lot bigger).