Osmosis- the truth

[cimo]

From long past converstaions on the subject, I found the risks somewhat overstated in certain circles.

Then I read this.

http://www.yachtsnet.co.uk/osmosis.htm

Gave me the confidence to perform my own "survey" when I viewed my 1979 hull before buying. Certainly put my mind at rest.

 

[bikedaft]

All 1970s boats will have some blistering. Not a problem. Simples.

not tru for ours either - 1973 halcyon clipper 27, rarely out for the winter (maybe 3 winters out of 39!)

 

[30boat]

What people sometimes don't realize is that a hull can be blister free and still suffer from osmosis.All that's needed is a poor quality permeable gelcoat.
My boat has millions of tiny blisters. When a sample of gelcoat is removed the underlying laminate is in top condition so until they go further down the laminate I won't worry about it.

 

[BobnLesley]

By Luck or foresight?

"...1973 Albin Vega owner here, no osmosis..."

Good reason number 143 for buying an Albin Vega: Fom the very first, Vegas were built using transparent isophthalic resins; despite there being over 3500 built, I doubt if the number which have suffered osmosis beyond 'an odd blister' runs into double figures.

 

[single]

From long past converstaions on the subject, I found the risks somewhat overstated in certain circles.

Then I read this.

http://www.yachtsnet.co.uk/osmosis.htm

Gave me the confidence to perform my own "survey" when I viewed my 1979 hull before buying. Certainly put my mind at rest.

Very interesting write up, thanks.

 

[Marsupial]

Osmosis is a problem that varies in severity, often its a couple of blisters on the surface of a well laid-up grp in which case there is little to worry about. The worst cases are where the GRP has little or no resin or the resin has not cured or is not mixed properly (the definition of osmosis) the thickness of the layup makes no difference in this case. osmosis does not respect marque; any boat can suffer and examples of all have fallen victim to it. The solutions offered by the industry are often overkill and this has spoiled their pitch. If the boat is floating then obviously osmosis hasn't sunk it so evidence of it sinking boats is hard to find. When the gel coat is removed you may often find a resin free laminate which could have caused the boat to sink if the blister had burst.

 

[Avocet]

I can't answer the poll because there's no option for "depends how bad it is" - which is what I'd go for. As has been said, they can vary from a few tiny little pinprick blisters, right up to big egg-sized (fried!) lumps with lots of fluid behind them, and extending quite deep into the laminate. The former wouldn't bother me, the latter MIGHT not bother me (depending on how cheap the boat was). Also, I'd like to add that Avocet is a 1972 fibreglass boat and I've not found any blisters yet,