Polyurethane Foam install

[Ok J]

Hello all,
I am about to pour my newly reconstructed hull (stringers, floor, transom) and need a little advice on a few topics.

1. Diameter and spacing of holes in the floor for good distrubution of the closed cell material
2. amount to attempt at one time at 70 degrees F

3. best method to transfer the material into the cavity with (funnel?)

I do understand the basics of the material and will have help to pour, any advice from those in the know, would be appreciated.

Thanks,
-Ok J

[Ok J]

More info...The hull is an 18 ft FG OB of 1979 vintage, forgot to include that!
Thx.

[longliner45]

I know it expands a bit,and makes for nice floatable air tight compartments

[legendinownmind]

Drill as many holes as possible say every 18 inches and big enough for the foam to pour without spilling on to the floor. Try to elevate the front end so that the foam settles toward the back and start pouring the foam from the back.Also drill a half inch hole in the floor at the transom for air relief.Dont mix up over two quarts at a time of A and B until you get a handle on it. The biggest precation is to keep the foam from distorting running surface. It is preferrable that the boat be on a jig that supports the hull bottom. As new boats are foamed in the mold and yours is obviously not, warpage is possible.

[dereksireci]

A scale can be handy in this case. Assume the material will be about 2 pounds per cubic foot when expanded. Measure the area to be filled with each pour and mix up only the amount necessary to do the job. Have acetone handy because it will mar the gelcoat finish. If you just wipe it with a dry rag it will appear clean but a stain that can only be buffed out will appear later. Don't pour too much at a time because the material will exotherm (gets hot). I've used rolled up thick paper and taped it together to make disposable funnels. We foam with the boat out of the mold with no problem.

Recently there was a USCG publication posted on this forum recently called "SAFETY STANDARDS FOR BACKYARD BOAT BUILDERS" Read it over and avoid putting way more foam than is required. Correct placement is just as important as the amount you install. Often we leave the forward area in between the stringers void of foam. Foam in this area will tend to contribute to capsizing when swamped, if it is left empty it will flood and actually increase stability.

This is the page I use:

http://www.uscgboating.org/safety/boatbuilder/flotation_landing.htm

djs

[Ok J]

Thanks for the reply, your info helps me out quite a bit. My boat is sitting on a jig that supprts the transom and the very perimeter on the hull (off the trailer). I hope I don't encounter any distortion to the underside while pouring...trial and error...I hope not!

Thanks again

Ok J