rudder design for my proa..
here are a couple of exploded jpegs of the rudder design i am building for my proa. This rudder is beam mounted, and the rudders (two, one in each bow), hang off of lower bolts to swivel out of the way after shunting. There are control lines not shown that tie the two rudder systems together so that the water pressure of one rudder being active pulls the other rudder even further up out of the water (by swiveling, not lifting the foil). The foils are foam/glass/resin and slide in a cassette made of glass/carbon/resin that attaches via continous hinge/pintle to glass/resin'd stock that is swiveled on a bolt into place against the rudder mounting beam by lines.
These pictures are a bit crude as i do not know Sketchup well (yet, fun program). Still the pictures provide the idea.