Re: question about building sailboat hull ...

Bolger's "Instant Boats" (books and plans available from H.H. Payson,
http://www.instantboats.com) offer an easy construction method that does
not require lofting (Look into this if you plan to build a traditional
boat -- means drawing the plans full scale so that  you can find the
mistakes in the measurements given in the published plans and so that
you can make patterns for actually building. Many first time builders
get so discouraged in the lofting phase that they never get to the
actual building phase.) or a strongback (the cross-piece frame).

BTW, traditionally, what you are calling a frame is usually called
"molds" (or "moulds"). In traditional terminology, frames are a
permanent part of the boat.

I was looking at a site that showed a home builder's sailboat.  He had some
plans, set up a frame on the ground and made a cross piece frame ..

He used plywood to sheath the boat.  Epoxy on the plywood.

Two things ...  when building a hull, do you first need a backbone,,,
keel,,, or whatever??

Another ,,,   if you use plywood, can you glass over the ply and the ply
becomes a core?