Expanding foam filler

   Does anyone have any experience of using weatherproof expanding foam on boats?

I'm thinking of using it for packing rather than anything structural. If I cut/sand it, will it absord water? Can I paint to seal it?

Thanks for any advice. 

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GarethT Send Private Message Find Member's Posts Really should get out more Joined: 21 Apr 07 Online Status: Offline Posts: 714	Post Options Post Reply Quote GarethT Report Post Quote Reply Topic: Expanding foam filler Posted: 08 Oct 17 at 9:44am
	Does anyone have any experience of using weatherproof expanding foam on boats? I'm thinking of using it for packing rather than anything structural. If I cut/sand it, will it absord water? Can I paint to seal it? Thanks for any advice.

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: 6662	Post Options Post Reply Quote JimC Report Post Quote Reply Posted: 08 Oct 17 at 11:05am
	It will absorb water and its fairly heavy (well by foam standards. I suppose you could paint it. The biggest problem I'd have though, if you are using it to pack inside tanks, say, is that water will lie between it and the main structure. If the main structure is wood that means rot, and if the main structure is glass, that means osmosis.

423zero Send Private Message Find Member's Posts Really should get out more Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3420	Post Options Post Reply Quote 423zero Report Post Quote Reply Posted: 08 Oct 17 at 11:14am
	plus, it can generate pressure and cause bulges.

zippyRN Send Private Message Find Member's Posts Far too distracted from work Joined: 14 Sep 06 Online Status: Offline Posts: 437	Post Options Post Reply Quote zippyRN Report Post Quote Reply Posted: 08 Oct 17 at 4:34pm
	i think Jim C and 423 zero have covered the main issues

GarethT Send Private Message Find Member's Posts Really should get out more Joined: 21 Apr 07 Online Status: Offline Posts: 714	Post Options Post Reply Quote GarethT Report Post Quote Reply Posted: 08 Oct 17 at 4:46pm
	It’s for the bottom of a tasar daggerboard case, to give something that can be rubbed down/faired. The foam that’s in there is a bit ratty so I’m just looking for something quick and cheap to fill the bottom half inch. Any time spent working on it comes out of my sailing allowance so I don’t want to strip out all the existing packing and start from scratch. Edited by GarethT - 08 Oct 17 at 4:47pm

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: 6662	Post Options Post Reply Quote JimC Report Post Quote Reply Posted: 08 Oct 17 at 5:01pm
	I'd be inclined to blag some offcuts of proper boat building foam, shape them and glue them in with epoxy and filler. You need to be quite careful round daggerboard cases because its suprisingly easy to bend them in that fatal fraction of a millimetre that stops the board going up and down readily.

2547 Send Private Message Find Member's Posts Really should get out more Joined: 11 Aug 11 Online Status: Offline Posts: 1151	Post Options Post Reply Quote 2547 Report Post Quote Reply Posted: 08 Oct 17 at 5:24pm
	I think in Aus they are gluing in packers that actually match the profile of the board now rather than have a rectangular hole.

Do Different Send Private Message Find Member's Posts Visit Member's Homepage Really should get out more Joined: 26 Jan 12 Location: North Online Status: Offline Posts: 1312	Post Options Post Reply Quote Do Different Report Post Quote Reply Posted: 08 Oct 17 at 6:41pm
	You talking a smallish amount? Epoxy resin and micro balloons perhaps? Those cans of expanding foam are not cheap, pretty hard to control and I've not had much luck on revisiting them so end up a single use unless you're better than me at cleaning the nozzle.

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: 3401	Post Options Post Reply Quote Sam.Spoons Report Post Quote Reply Posted: 08 Oct 17 at 7:23pm
	Builders expanding foam is unsuitable for this job (and, like DD I've never had much success reusing a can after the first use). Two pack PU foam is good for larger voids, I have used it in the past to repair sailboards but even that has a somewhat variable cell size and is relatively heavy but it is pretty much closed cell so does not readily absorb water. But it is also very soft and not what I would use either. Depending on precisely what you are doing with it, epoxy and micro balloons would also be my suggestion, it is light and sands well but is properly impervious and hard wearing (which expanding foam is not). However, the exposed foam in your DB case, is it there to fair the case or is it that the DB has worn away the skin layer through to the foam core? if the latter you are probably going to have to do a more sophisticated repair or you'll simply be storing up problems for the future. Edited by Sam.Spoons - 08 Oct 17 at 7:24pm
	Spice 346 "Flat Broke" Blaze 671 "supersonic soap dish"

GarethT Send Private Message Find Member's Posts Really should get out more Joined: 21 Apr 07 Online Status: Offline Posts: 714	Post Options Post Reply Quote GarethT Report Post Quote Reply Posted: 08 Oct 17 at 7:41pm
	Is a big wide (fore and aft) case designed to allow the DB to pivot. Now everyone packs it out with foam to the db just goes up and down. I just want to tidy up the bottom end. I'm not sure if anything other than 'foam' is allowed for packing. Can't find anything specific in the class rules.