Model Forum / Radio Controlled / Water Models / June 2008

I would not advise using the spray foam from the hardware store. It
continues to expand for a long time and I have seen decks get blown
right off boats when it expands too much. It can also absorb water over
time and become very heavy. Most people use pool noodles. I usually use
the foam pipe insulation that you can buy at Home Depot or your
hardware store. It's basically the same stuff as the pool noodles. You
just have to be sure you use enough flotation to float your boat.  Doug

Like Doug said, stay well away from that spray foam stuff.  

Pool noodles are great and cheap but you need to seal any parts you
have cut with a heat gun or they will absorb water over time as well.
This isn't critical as it takes a year or so of use before they soak up
water and are easy to replace.  Just make sure you have enough stuffed
in the hull to make it float.  Do a float test in the shallow water.

Another foam to use is closed cell foam. Like what they use for those
thin camping sleeping rolls you see in Kmart - the ones hikers use.
These don't soak up water and are very buoyant.  I try to use this
stuff in my boats.

I use 2=3 coats of a craft sealer called Mod Podge for
sealing foam and wood.  It is a water based polyester
product that can be brushed, sprayed or poured.  It dries
quickly and , like polyurethane varnish, it is fuel proof -
http://www.dickblick.com/zz029/16/ .  They have an outdoor
version available, but I have always used the matte finish
version.

As for foam, I use the 2" white styrofoam building
insulation from Home Depot.  I use a band saw with a metal
cutting blade, a hot wire, and/or sandpaper to cut the foam
to fit into every unused open space under the deck.  The Mod
Podge seals the foam and holds it in place.  For insurance,
I may use balsa sheeting to close off the foamed areas, all
sealed with the Mod Podge.  You can also use brown wrapping
paper and Mod Podge in the same way one would laminate with
fiberglass cloth and resin to cover the foam and/or make
bulkheads to seal the foam from access by fuel or water.

Hope this helps.
Randy

"sea hawk westoz"
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