Toller wrote:

Is there anything inherently wrong with making a solid rudder, possibly
covered with fiberglass?

Well, we are considering replacing the rudder on our ship, and will
certainly go for solid wood (no glass, no plastic). The ship is from 1897,
and as far as I know, most of the rudder is from around the same time.
There has been a few repairs over the years, of course, and it is about
time to replace it all, but anyway, it has stood the test of time. I expect
the new one will be good for at least the next 30 years...

-H