buoyancy foam

[SteveGorst]

I am thinking of buying an Etap with built in buoyancy foam. I have had an opinion expressed to me that should a minor leak occur through the external hull the foam could become waterlogged and obviously cause problems.

I must admit I am a bit sceptical about this myself as the foam is supposed to be closed cell foam but I thought I better check out the experiences of others to see if there is any truth to this before I make an expensive mistake.

Am I right to be sceptical?

Cheers
Steve

 

[SimonD]

I had a look at a Sadler 34 with a view to buy a few months ago. There had been some damage to the hull at some time which had let water into the foam-filled gap. I also suspect that the foam had lost adhesion with the GRP.

The surveyor found high moisture levels at various places above the waterline and signs of blistering on the topsides(!) I conclude that the foam trapped water and held it against the inside of the hull (bare GRP, no gelcoat). The effect looked pretty horrendous.

Now there are those who say that this is not a problem, but it struck me as a serious design hazard and it's rather put me off foam filled boats.

 

[vyv_cox]

The foam used to fill both Etaps and Sadlers is closed-cell poyurethane that is almost totally impervious to water. The same stuff is used as buoyancy for lifeboats, but as separate blocks, not built in. When controlled in industrial conditions its closed cell content will be well over 95%. By contrast, the foam available for DIY use cannot be controlled in anything like the same way and it does become waterlogged.

Where problems occur, and the post about the Sadler 34 is one, is where impact damage causes a loss of adhesion between the hull and the foam. Water can then accumulate between the two, where it can lead to absorption into the GRP. If the foam fragments, it will allow water further into the structure, but this does not mean that it will absorb water.

I suggest you speak to Etap and look at <A target="_blank" HREF=http://www.etapyachting.com/index.cfm?Part=Yachts&Page=Unsinkability>http://www.etapyachting.com/index.cfm?Part=Yachts&Page=Unsinkability</A> for some more reassurance.

 

[aztec]

sod all to do with boats, but the insulation on the top and sides of my freezer, was waterlogged and condensation was forming on the outside!

i stripped off the top and removed the offending wet foam, replacing it with the poy stuff from B&Q. cheating...yes, but it worked a treat, and i am going to use it on my fibreglass dingy which has been re-laminated after it was damaged.

the freezer works better than before, but i didn't think it would work, so worth a try.

so i'm a tight arse? best wishes, steve.

 

[SteveGorst]

Thanks for the advice, I guess if I look out for any damage to the hull and make sure the surveyors report doesn't show up any suspiciously damp patches I should be ok. This is my first yacht and I have been reading stories in the magazines such as yachts nearly sinking through damaged rudder pins and minor details like that. My last boat was an unsinkabe fishing boat, a SeaHog, so I am attracted to the same principles being applied to a yacht, especially with my family on board!
Regards
Steve

 

[SimonD]

I entirely empathise with your concerns over families and sinking boats. I'm sure a half decent surveyor would do this on a faom filled boat, but I would just check that he takes moisture readings from the topsides and deck as well as below the waterline. Also, Vyv is right - the boat I looked at had suffered serious impact damage. Mind you, I think flexing could have the same result, although this would be OK so long as water didn't get in.