Advice on expanding foam
 

A friend is restoring an old fiberglass Moth sailboat. The side decks/
floatation tanks are very thin and flexible, and he wants to give them more
support by filling the tanks with expanding foam.
He has both 4 lb/cu ft and 8 lb/ cu ft foam liquids, and plans on standing
the boat on the stern and pouring the mixture in several stages, so the
expansion doesn't get out of hand.

I've not used this stuff before, so can't help. Is there anything he should
be aware of before he starts? How large a hole should he have for expansion
of the last batch ? Can he mix component "A" of the two densities to yield 6
lb/cu ft? Any other advice?

On Tue, 19 Apr 2005 20:55:34 -0400, "Garland Gray II"
wrote:

A friend is restoring an old fiberglass Moth sailboat. The side decks/
floatation tanks are very thin and flexible, and he wants to give them more
support by filling the tanks with expanding foam.
He has both 4 lb/cu ft and 8 lb/ cu ft foam liquids, and plans on standing
the boat on the stern and pouring the mixture in several stages, so the
expansion doesn't get out of hand.

I've not used this stuff before, so can't help. Is there anything he should
be aware of before he starts? How large a hole should he have for expansion
of the last batch ? Can he mix component "A" of the two densities to yield 6
lb/cu ft? Any other advice?



Polyurethane foam bulges long term after heating.

Brian Whatcott Altus, OK

Thanks Brian, I wasn't aware of that. I assume you mean heat from air
temperature and sunlight. Is it a significant amount, and would the less
dense foam have less force? I'm wondering if he could somehow pour a limited
amount of the liquid into the inverted boat so foam would adhere to the deck
to give support yet not fill the tank. But I doubt the bond would be
sufficient to do this, especially over time.
My other concern was any problem of the foam eventually soaking up water
from the inevitable leak.

"Brian Whatcott" wrote in message
...
On Tue, 19 Apr 2005 20:55:34 -0400, "Garland Gray II"
wrote:

Polyurethane foam bulges long term after heating.

Brian Whatcott Altus, OK

Come to think this problem crops up in the notes of aircraft
home-builders where skin thicknesses are as small as possible.
Perhaps the effect could even be advantageous under thick skins?

It is noticed after parking in hot sun.

Brian W

On Wed, 20 Apr 2005 06:18:23 -0400, "Garland Gray II"
wrote:

Thanks Brian, I wasn't aware of that. I assume you mean heat from air
temperature and sunlight. Is it a significant amount, and would the less
dense foam have less force? I'm wondering if he could somehow pour a limited
amount of the liquid into the inverted boat so foam would adhere to the deck
to give support yet not fill the tank. But I doubt the bond would be
sufficient to do this, especially over time.
My other concern was any problem of the foam eventually soaking up water
from the inevitable leak.

"Brian Whatcott" wrote in message
.. .
On Tue, 19 Apr 2005 20:55:34 -0400, "Garland Gray II"
wrote:

Polyurethane foam bulges long term after heating.

Brian Whatcott Altus, OK

So I guess you are thinking this might not be a problem if this floatation
tank/deck has a thick enough skin?

"Brian Whatcott" wrote in message
...
Come to think this problem crops up in the notes of aircraft
home-builders where skin thicknesses are as small as possible.
Perhaps the effect could even be advantageous under thick skins?

It is noticed after parking in hot sun.

Brian W

On Wed, 20 Apr 2005 06:18:23 -0400, "Garland Gray II"
wrote:

Thanks Brian, I wasn't aware of that. I assume you mean heat from air
temperature and sunlight. Is it a significant amount, and would the less
dense foam have less force? I'm wondering if he could somehow pour a
limited
amount of the liquid into the inverted boat so foam would adhere to the
deck
to give support yet not fill the tank. But I doubt the bond would be
sufficient to do this, especially over time.
My other concern was any problem of the foam eventually soaking up water
from the inevitable leak.

"Brian Whatcott" wrote in message
.. .
On Tue, 19 Apr 2005 20:55:34 -0400, "Garland Gray II"
wrote:

Polyurethane foam bulges long term after heating.

Brian Whatcott Altus, OK