I have this on my boat. The previous owner got a sheet of fiberglass, maybe 3/16" thick and fiberglassed it to the bottom of the rudder. It only sticks out about 3-4 inches all around the rudder (sides, front & back). I couldn't tell you if he used any screws or if it's just fiberglassed on, but it's plenty strong. I've had the boat 10 years and it never given me a problem in regards to catching things, we don't sail in lobster country, but we do get our share of crabpots.

The boat is an Irwin 10/4, so 25' with a >3' draft and about 8000lbs, not the size of yours. I have talked to other owners of these boats who say their rudder could use more bite, which is not something I've noticed, so I do think it makes a difference. In regards to strain it adds to the rudder bearings, I would think it adds some if you did a lot of hobbyhorsing as the rudder is less inclined to move vertically through the water. I can't see there being a lot of drag associated with it just from making headway as it's fairly thin.

Rob Johnston
Irwin 10/4
New Bern, NC