Buoyant foam

   The clue is in the name, "styrofoam/polystyrene". The solvent in polyester resin is 'styrene' and will dissolve styrofoam with extreme prejudice.
Also polystyrene (and polyester resin based gap) absorb water to varying degrees.

Most early high performance sailboards were constructed with epoxy and polystyrene when surfboards and early/lower tech sailboards used PU foam and polyester resin.

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Sam.Spoons Send Private Message Find Member's Posts Really should get out more Joined: 07 Mar 12 Location: Manchester UK Online Status: Offline Posts: 3393	Post Options Post Reply Quote Sam.Spoons Report Post Quote Reply Topic: Buoyant foam Posted: 24 Aug 18 at 7:42pm
	The clue is in the name, "styrofoam/polystyrene". The solvent in polyester resin is 'styrene' and will dissolve styrofoam with extreme prejudice. Also polystyrene (and polyester resin based gap) absorb water to varying degrees. Most early high performance sailboards were constructed with epoxy and polystyrene when surfboards and early/lower tech sailboards used PU foam and polyester resin.
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423zero Send Private Message Find Member's Posts Really should get out more Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3399	Post Options Post Reply Quote 423zero Report Post Quote Reply Posted: 24 Aug 18 at 6:45pm
	Must have cut up 30 of these boards last time we had a skip, hardly any abandoned boats or anything else really, we have half a dozen large blue barrels full of sails and dozens of masts and booms.

iGRF Send Private Message Find Member's Posts Visit Member's Homepage Really should get out more Joined: 07 Mar 11 Location: Hythe Online Status: Offline Posts: 6496	Post Options Post Reply Quote iGRF Report Post Quote Reply Posted: 24 Aug 18 at 6:21pm
	Go down to the nettles in most clubs and you'll find an old sailboard or two, lots of them are filled with a good quality low density styrofoam. Mistral, F2, Fanatic are probably best of the old ones..
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423zero Send Private Message Find Member's Posts Really should get out more Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3399	Post Options Post Reply Quote 423zero Report Post Quote Reply Posted: 24 Aug 18 at 6:02pm
	May try to deck over, I have access to sheets of glossy white GRP. Have seen foam react, don't fancy spending hours shaping something to see it melt.

JimC Send Private Message Find Member's Posts Visit Member's Homepage Really should get out more Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6644	Post Options Post Reply Quote JimC Report Post Quote Reply Posted: 24 Aug 18 at 12:00pm
	Dow Floormate is styrofoam, so basically yes. However there are an awful lot of grades of styrofoam, and when I researched it they seemed to vary greatly in the amount of water they take up. I'm not sure to what extent you can get spec sheets from ebay vendors or even trust them to send what the spec sheet says. You can put an epoxy/glass layup on styrofoam, but I'm pretty sure polyester will reduce it to a sticky mess. Edited by JimC - 24 Aug 18 at 12:02pm

423zero Send Private Message Find Member's Posts Really should get out more Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3399	Post Options Post Reply Quote 423zero Report Post Quote Reply Posted: 24 Aug 18 at 10:06am
	Would this stuff do ? https://www.ebay.co.uk/sch/i.html?_sacat=0&_nkw=styrofoam+block&_frs=1 Would you be able to lay GRP straight on to this once you have required shape ? Looking to increase buoyancy at stern of Sprint, intend to fill both sides of deck, going forwards approx' 18", will put 2 ports through to maintain drainage, with flaps to prevent water ingress. Edited by 423zero - 24 Aug 18 at 10:33am

JimC Send Private Message Find Member's Posts Visit Member's Homepage Really should get out more Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6644	Post Options Post Reply Quote JimC Report Post Quote Reply Posted: 24 Aug 18 at 9:58am
	Dow Floormate doesn't take up much water. I've used it for boats.

423zero Send Private Message Find Member's Posts Really should get out more Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3399	Post Options Post Reply Quote 423zero Report Post Quote Reply Posted: 24 Aug 18 at 9:40am
	Is their a buoyant foam available that doesn't take up water ? Looking for something fairly rigid too and that can be shaped.