hull materials

I remember reading back before world war 2 several companies were making
wood aircraft ( lockheed, Timm, deHavalin ect.) by using thin wood sandwitched onto an inside plug - and maybe an outside mold too. I think
some used a heat curing resin and autoclaved the whole thing. Lockheed
used concrete for their molds somehow.
Are there ways to make a plywood inside plug which would have formers
and plywood skin maybe coated with jell-coat and sanded slick. Then
start adding long strips of thin wood using epoxy or recorsonal and laminate
the thing up about 5 layers thick overlapping the joints and crossing the
grain directions. Would this still be doable for the 15- 25 foot long range?
Maybe somehow use a vacuum bag to hold the layers down while they cure.

Just thinking out loud .....
Tim

 

The technique is called cold-molding.

Glen-l.com/methods

You could make the hull laminate on station molds, but you'll need framing inside the hull in most cases anyway so laminating over the framing probably makes more sense.

Lurvio

 

also my personal favorite building material.
Beauty with CMP is that you can get all the bulkheads, dividers and most of the furniture installed with the frames before laminating the plywood hull...

 

Check out the Gougeon brothers book. Titled appropriately: The Gougeon Brothers On Boat Construction. There is enough information there to keep you off the streets and out of bars for years. Plenty of text, pix, and proven advice about cold molding. The book is worth more than its cost. ....and no I am not connected with these guys in any way except in recognition of their craftsmanship and knowledge.

 

Don't pay any attention to Messabout, he's been getting a 20 dollar bill once a month for years, to plug their stuff . . .

In all seriousness, cold molding is a fine way to get a hull, though I find it a bit fiddly for the novice builder. You're much better off building over a male jig, built from station molds and fairly closely spaced stringers (depends on how thick the first veneer is).

In WW II (and prior) they used resorcinol (phenol) and urea formaldehyde formulations as the adhesives, which replaced the fish guts or mammal milk glues employed until WW I.

It's a well covered subject with many texts available. Check out the book store here.

 

"In all seriousness, cold molding is a fine way to get a hull, though I find it a bit fiddly for the novice builder."

However the advantage for the novice is a piece of hull is fitted one at a time.

So even tho the piece may be trimmed 5 - 10 times , it will finally fit , so the $crap box stays small.

In addition with modern epoxies and a good staple gun the amount of hull built at one time can be 15 min or 12 hours , great for the novice!

FF