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foam flotation questions

1694 Views 14 Replies 6 Participants Last post by  DuckNut
I've started on replacing the deck (3/8" ply) in the 17 ft Sea Nymph aluminum.

The height (center of the v hull to deck) varies from about 4 inches near the transom to about 12 inches forward. The aluminum ribs are spaced at 12 inches and the current deck support attached to the ribs (every other one) spaced at 24 inches.

flotation foam:
I not sure if I like the idea that the urethane foam will adhere to the hull and deck supports.
Should I ever want to inspect the inside of the hull the foam would be a pain to remove so I'm thinking to line the hull with aluminum foil so it sticks to that and would be easy to remove.
(I don't foresee having to remove the foam but don't see how it could hurt)

Any argument for/against?
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· Brandon, FL
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If you put the two part foam under there in a few years your boat will weigh an extra several hundred pounds because of all the water it absorbed.

Find a source for the type of foam that pool noodles are made from (in sheet form). That plastic/rubber feeling stuff. Cut to fit and glue a few spacers to the hull to keep it off the hull and water can drain out and it can dry under the deck.

I think I saw the rebuild thread on this...where is it?
 

· Brandon, FL
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12,696 Posts
At least half the Styrofoam I took out I plan to reuse but had thought to fill in any open spaces with the two part around the Styrofoam to make it "fit perfectly" :) under the deck, no space between the plywood and foam. If i can find a source for larger pieces of Styrofoam I might just do that.

The two part foam is supposed to be 90+ % "closed cell". If it starts absorbing water in just a few years F that... I don't expect any leaks but I do go out in the rain.
The foam WILL start absorbing the moment it gets wet. Then it only gets worse. When the wet foam is in contact with the aluminum hull it will corrode holes in it.

In the past some boat builders foamed in their fuel tanks and they all leak because of this, but they have learned their lesson. Aluminum is a tough material but it needs to get air.
 

· Brandon, FL
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12,696 Posts
TheFoamfactory.com has 1"x48"x108" for $63. If they would cut it to the width between supports you would be in business. Buoyancy is a little more than 60lbs and one sheet would add about 270 lbs of buoyancy.
 
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