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Re: Great Stuff Expanding Foam under Seat
By:John Monfoe
Date: 5/18/2001, 5:09 am
In Response To: Re: Great Stuff Expanding Foam under Seat (Paul G. Jacobson)

: Just be careful that you don't use that stuff in a confined, or closed area
: of the boat. It needs room to expand.

: My old clark Craft catalog shows the proper aplication of expanding foams in
: sealed areas: make the area in the hull without a top. Fill the area with
: foam, which will probably overflow. After the foam has cured, level it
: off. Then fit the deck on top. Otherwise, the force of expansion can cause
: the hull or deck to bulge, and possibly loosen or break a seam.

: if you use the less expensive sheets of build foam you can shape them to fit
: the curvature of the hull eaasily. Use spots of rubber cement to tack down
: a sheet or two of coarse sandpaper to the area you want to fit. With
: slight pressure on the sheet of foam (lean on it a bit) slide the block of
: foam back and forth until the sandpaper removes the extraneous material.
: Lift up the sandpaper and rub off the rubber cement.

: It is a good idea to seal the foam inside a layer of fiberglass cloth and
: epoxy resin, as this strengthens the foam and keeps it from flaking into
: little pieces. Be sure the resin layer is complete so no water or water
: vapor gets into the foam.

: PGJ

Hi Paul,

I really like your sandpaper idea and I will use it. Originally I was going to fit layers of foam in the stern and bow before I mated the deck and hull, but because my deck was curling and cracking so bad I had to quickly put them together before anymore damage occurred. Now my plan is to blow up an air matress to put the kayak on to relieve hull stress while I craw inside and shape the foam in layers and glue them together. When I get to the edges where shaping is just too difficult I thought I would use the foam to fill in the last fit to the bow and stern. I certainly don't want to put pressure on the ends to cause dammage. I don't think this will happen if you give the foam a tapered hole that gets bigger as the foam expands outward without any semi-boxed in areas for the foam to get trapped in. In my experience, I once built an 18" box of plywood in around an epoxy coated model and I put in several 2" holes in the sides and back to let the two part foam expand through so the box didn't warp. It didn't work and the really strong box bulged on all sides. But the paper 1/2 gal container that contained the left over foam looked like an ice cream cone after the foam set up. The fragile container wasn't hurt at all and all of the force came upward out of the tapered bucket. If you look at the seat you will see I have 30 lbs of weight on it and the seat didn't lift and the excess foam came out the escape area in front. This is what I picture happening in the bow and stern fill area's with the foam. If it doesn't work we will learn something.

Take care,
John

Messages In This Thread

Great Stuff Expanding Foam under Seat *Pic*
John Monfoe -- 5/17/2001, 5:32 pm
Re: Great Stuff Expanding Foam under Seat
Rick -- 5/20/2001, 11:33 am
Paul & Rick.
John Monfoe -- 5/21/2001, 6:50 am
A: Build boat; B: Try it out; C: Add flotation?
Paul G. Jacobson -- 5/21/2001, 10:18 pm
Re: A: Build boat; B: Try it out; C: Add flotation
John Monfoe -- 5/22/2001, 10:39 am
A: Build boat; B: See A :)
Paul G. Jacobson -- 5/22/2001, 11:31 pm
Re: A: Build boat; B: See A :) *Pic*
John Monfoe -- 5/23/2001, 6:25 am
Re: Great Stuff Expanding Foam under Seat
Paul G. Jacobson -- 5/17/2001, 11:55 pm
Re: Great Stuff Expanding Foam under Seat
John Monfoe -- 5/18/2001, 5:09 am
Expanding Foam elsewhere
Paul G. Jacobson -- 5/20/2001, 11:38 pm