You can see the sequence I'm using at
http://home.earthlink.net/~derbyrm/Chebacco.html

The keel goes on after the bottom is epoxied to the bulkheads (but,
hopefully, not to the molds).

"Stitch and glue" is another scheme. It requires no building forms/molds
and any keel is added later.

Most plywood construction does have a layer of fiberglass on the outside
these days, but the glass reinforces the epoxy to preserve watertightness of
the wood, not the hull. It doesn't add any significant structural strength
to the hull. (To reinforce against mostly submerged logs and jetsam from
the container ships, one would have to add it to the inside of the hull.)

Roger

http://home.insightbb.com/~derbyrm

"Wayne.B" wrote in message
...
On Wed, 28 Dec 2005 18:51:08 GMT, "Thomas Wentworth"
wrote:

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

Not necessarily since there are many different ways of
building a boat, but building a backbone and frame/mold
is certainly a time honored method.


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

You can but you end up with a relatively heavy boat by
modern standards.