wrote:

What techniques should I research for changing the hard corners
where
two ply surfaces connect? How do I shape those round edges smoothly
to
have a professional looking curve?

Plywood seems to be a good core for the large surfaces. I may use
two
or three 1/4 ply layers glued with epoxy. 1/4 inch ply will allow
some
curve to the sides and top, and having multiple layers will provide
strength. This is a 50 foot boat, so 1/2 to 3/4 inch thickness would
not look too flimsy, and the boat can accommodate the weight.

You are going to end up making a male mold and then doing a classic
"one off" construction.

I definitely would NOT use plywood as a core material, but rather use
1/2" Divinycell foam.

Best guess is probably about $3/sq ft for full 4x8 sheets.

Probably get the job done with 2 sheets so estimate maybe $200 for
foam.

Foam can be cut into strips to go around corners, I've done it several
times.

You do realize that this will be at least a 2 year project and cost at
least $1K before you are done.

Lew