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Hi,

A number of weeks ago, I posted a question on this group about building
a composite hot tub by "borrowing" some boatbuilding methods. I've been
looking at cold-molding vs sheathed strip (is this synonymous with wood
cored glass?).

snip

My question is this: If you are planning on using this type of "cold
molding", and plan on encasing everything in glass in the end, what
type of glue/epoxy can you get away with for the layers of wood in
between?

Epoxy.

I've read that a lot of the sheathed strip kayak builders get
away with using yellow wood glue (some even say they've used hot glue),
knowing that the fiberglass is going to provide a moisture barrier.

With sheathed strip, there is only one single layer of wood, which is kept
together by the glass on both sides. Glueing the strips together is only
necessary to keep them together until the glass goes on. Nails could be used
as well.

However, with could moulded, you have more layers of wood which will only
keep their shape when glued together very rigid. So in this case you MUST
bond the layers together very well.The glass is not providing any or much
help to retain the shape. Could moulded can even be used without glass
sheathing, as Paul Gartside does.
And since it is impossible to privide the necessary clamping force needed by
ordinary glues to get a decent bond, you'll simply have to use epoxy for
this which does not need any clamping force at all.

And as said earlier, don't go blind on the cost of epoxy, it will only be a
fraction of the total cost of the boat.

Meindert