water logged foam

[StephenSails]

Hi,

I am doing up an old Foxcub 18, she is pretty sound but there are a few problem areas. The closed cell foam in the forward tank is water logged as the fore hatch has been leaking.

I have drilled a few holes in the hull to drain water which I will make good later, but the foam is still pretty wet, I think the only answer is to get the foam out and replace with new stuff. My mate said I could try pouring acetone over it which would melt it, I could then let it drain out my existing holes and bail out the remaining soup. Sounds like it could get too messy, does anyone else have any better ideas?

Also, does anyone know any thing about the Foxcub 18, information seems short on the net. Any ideas on how it will sail etc etc would be gratefully received.

Cheers

Stephen

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[oldsaltoz]

G'day Stephen,

If this stuff dissolves it sure isn't closed cell balloons, it's rubbish and black enamel basket weavers who builds boats using this stuff should be shot. Or better yet set adrift in their own work.

The problem is that the foam supports the inner and outer layers of glass, if it turns to mush [and it does] the hull, deck or whatever is weakened to the point that it is very dangerous indeed.
Even areas that show no sign of moisture are often no longer attached to the skin, and movement grinds it to a dust.

You should remove all of it; not a viable outcome on an older craft as you will never recover the time and money spent.

Even if you manage to get the crap out, you have no way of knowing the remaining surface is clean enough to get a proper bond when injecting new filler.

Walk away now, or swim away later if you can...........

Avagoodweekend.



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[snowleopard]

the common foam used to fill compartments is REP (rigid expanded polyurethane) which is formed by mixing 2 liquids. it has very low structural strength and is not truly closed cell as it can, as you know, become waterlogged.

once saturated there is no cure and it must be removed. the usual way is to hack it out with a sharp instrument but if it dissolves in acetone that might do the trick. you won't do much harm to cured GRP as long as you don't leave the acetone in there long-term.

the good news is that the mouldings are unlikely to depend on the foam for strength.

if you want to re-fill afterwards, the one-pack aerosol foam sold by builders' merchants is more flexible and less likely to fail.

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[tcm]

if using the builders foam - be careful, cos it is very powerful and could easily defom of perhaps damage two pieces of grp if over-confined. I wd use a series of 8mm holes, and just try one with some foam and leave overnight to expand fully, which will allow you to see how much to use from there.

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[aitchw]

You have my sympathy,Stephen, not least because I am facing some of your issues myself with a 16' Seasafe Dandy. Like you I can find little or no info and hate starting to apply surgery when I don't know what's underneath.

I have had some success drying out foam buoyancy in dinghies though it takes a long time. I don't know the volume of the block you are talking about nor whether the foam has degraded to the point it's not worth bothering with but if you carve out a hole in it clear through to the GRP as near the lowest point as poss you should find it tends to puddle at the bottom of the hole. By endlessly mopping this out, allowing air to circulate when practical and preventing further ingress it will slowly dry out. Over a summer I got rid of about 40lbs (4 gallons) of water from a hull with a design weight of 140lbs.

If you do decide to remove it I wouldn't use acetone or anything else to dissolve it. You'll end up with a horrible noxious mess in confined spaces. Just carve and scrape it out. It won't be as bad as it sounds.

Good luck

Howard

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[StephenSails]

Thanks for all the posts, I decided to start hacking in earnest today and all seems ok so far, lots more to hack out yet but its just an elbow grease job. I think I am going to clean it right out and then wash the tank with degreasing solvent and then paint a couple of coats of resin over the bare glass, after that I am tempted just to fill the thing with polystyrene blocks cut to fit, this must be a better form of buoyancy than the sponge type foam that is now water logged, I used to own a Silhouette MK3 and that had no foam in it at all so me thinks that if I were to be compromised by a severe water ingress it would probably be abandon ship anyway as the current foam obviously would not offer much buoyancy where it is positioned. Someone mentioned structural strength, well I do not think this is a big issue as it only a small area and the lay up is quite thick, if I had to stiffen it that would not be problem either but I think it is ok.

Thanks for all the advise so far.

Cheers

Stephen

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[aitchw]

If you use polysterene try wrapping your blocks in clingfilm. Polystyrene goes brittle and crumbly exposed to the atmosphere. The clingfilm excludes the air from it and keeps the loose bits from getting everywhere.

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[StephenSails]

Good tip, thanks.



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[Rick]

A few observations:
(i) the acetone idea only applies to polystyrene, not ployurethne or pvc foams
(ii) anyone who suggests it haas never tried it themselves! you end up with a much worse cleanup than just hacking it out.

I've found an assortment of tools will make the job farily easy - some broad, very sharp chisels (used to seperate foam from glass), a hacksaw blade with some tape wrapped at one end to use as a saw, and a good claw hammer - whack it in, twist 90 degrees, and pull some foam out.


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