Thread: How to use spray in foam for more flotation

If you use the spray foam in the floor you are almost guarenteed to block off a way for the water in the front of the boat to escape.

Here's a tip on the "sheet" foam. If you find that the foam isn't the exact thickness you can take a wire (piano wire or something similar) and heat it with a torch and use the cross bracing as a guide and then "fillet" the excess foam off. You may have to heat it several times and when you feel it getting "stiff" or harder to pull through the foam just come straight up and use the last of the heat in the wire to cut out what you've already done. It works really well and you can go with a thinner guage aluminum sheeting for the flooring, reducing some weight. As for the sides between the braces, I have a great idea for that area but, I don't want to tell just yet. I want to get it done and then post pictures of it.

The boat already has an aluminum floor with foam under it but very little elsewhere. This boat is a commercial boat and it does not have a coast guard certification of any type. It does not even have a label as to how much hp or weight on it. The cross-bracing is completely covered, there will have to be holes drilled in the side bracing covers and front end to get anything down in there. Thanks for all the advise!

I know West Marine sells that pour-in foam, But I too would be leary of blocking drainage to back of boat ( not seeing what your have) .
( not being a smart azz and for good of all here) boat can be replaced- you can't. Life vest? even inflatable kind..

Do you have a copy of the Coast Guard Booklet that covers flotation requirements and the calculation formulas? Try to get your hands on a copy and sharpen your pencil. Don't take it for granted that you're protecting yourself with adding foam wherever you have a void. If you're serious about your safety (or your family's) you should at least try to install foam in the amounts that will protect you. There are two formulas. One is basic flotation. This will keep the boat from sinking if swamped. The other is "Upright" flotation, which keeps the boat afloat and in an upright and level position of swamped.

I was an aluminum boat manufacturer for 40 years.

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I agree with wjw above. Check your existing situation thoroughly. Be sure you need it and
that what you add will help you out.

If you go the pour in 2 part foam, your best $$ deal is to buy it from Fiberglass , Epoxy , Composites, Carbon Fiber - U.S. Composites, Inc. I would go with the 3 pound per cubic foot specification.
There is a good FAQ page on their website. There are installation videos of various quality on YouTube.
I learned a lot of what NOT to do as well as what to do watching these.

Take some time to understand this product. Especially the installation. You are only going
to get one shot at doing it right. But with a little understanding you will do it easily.

best, dxr

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Do you have a copy of the Coast Guard Booklet that covers flotation requirements and the calculation formulas. Thanks for the info I found a copy on line and saved it. That is a great way to know exactly where to put the foam for maximum level flotation.

U.S. Composites is the best $$ value with the best information of anywhere I have looked.

I sure appreciate you guys taking the time to respond with all of the info above.

It should not be a problem plugging the water channels as I intend to put it in the very front of the boat and in the sides on the back.

Zrdc28 the spray foam works good my boat is a 17.5 Alum.bass tracker 1988, my wife and I got hit on a river, it was in the water for 14 hours before we got it out of the water, After the boat went under the barge it was still floating upside down, so the manufacture spray foam does work.

Originally Posted by crappiekiller2

urethane foam is what you need for boats.
Here is 1 site for it. There are other sites and you may be able to buy it local. This type of foam works great.

Urethane Foam , Expanding Marine Polyurethane Foam

Okay crappiekiller2, I have just order some of this stuff, is there anything I should know about the do's and don'ts of this application?