osmosis

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mj81

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is it really that bad to buy an old boat that has osmosis? say for example a boat from the mid seventies which has some blistering?would it not be ok to sand off and fill the blisters and apply suitable epoxy?
 
yeah thats what i was thinking but if im planning to keep the boat for a number of years and getting her at the right price its difficult to know what to do!!?
 
Blisters are not always osmotic, may be best to get a surveyor to do a litmus test on the blisters, or do it yourself. Often people mistake blisters for osmosis when it is not.
 
All grp boats suffer from "osmosis" (related to moisture content of the hull) to some extent or another so don't worry. Get a surveyor to have a look and be guided by him. Even if the blistering is "osmotic" it is not the end of the world. There are many yards that can cure the problem (at a price). As many have said "I have never heard of a boat sinking due to osmosis"

A gel coat strip followed by a few months on the hard "drying out" and washing (maybe with the application of heat lamps) followed by epoxy coating seems to be the answer. Depends on how extensive the blistering is and how much the boat would be worth if no blistering and how much you pay for it in the first instance.

The best advice you can get is be guided by your surveyor and if you are not happy "walk away" although if you get it for the "right price" then it might be worth having it repaired.
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The whole osmosis thing is over hyped. How many boats have sunk because of osmosis? Zero. Osmosis affects value and appearance, so if you buy an osmosis boat at a low price, treat the hull, then selling it is not going to be any greater a problem. (eg professional osmosis treatment costing say 15k on a 40ft motor boat and you buy for 20k less than market value for a clean hulled equivelent).

The main problem with osmosis are incompetent or rogue yards who do not have the right equipment or skills to deal with it thoroughly or properly. DIY treatment IMHO is not an option.
 
the one thing you shouldnt do is sand off and apply epoxy - you would just be wasting dosh and likely the epoxy would blister off fairly quickly.

by all means buy a boat with osmosis subject to the advice of a surveyor. but make sure the price is right, and be prepared to lose a lot of time out of the water if you have it treated.
 
Agree 100%, the gel coat needs to be removed, dried out, and the hull treated to remove the chemicals and moisture using a heated vacum pad system over an extended period, then re-coat after testing the treatment was 100% sucessful. It is very labour intensive and needs the right equipment, but it works.

BEWARE - There are very few specialist yards that can do this proberly
 
The quick answer is no it is not that bad, and if the blistering is minimal it can be a good bargaining point in your favour. If you can reduce the price you may indeed get a bargain. Without getting technical about "Osmosis" the term is abused considerably. What we should be discussing is the blistering of the gelcoat, and very often the laminate beneath it which is sometimes partly caused by water ingress. If the area is small and covered by small blisters in one area only it is indeed valid to treat locally. More extensive "pox" over large areas are perhaps a candidate for gelcoat peeling and full treatment but this can be expensive and sometimes only partially effective. The cost therefore has to be considered relative to the value of the boat. If you bought a very old cheap boat for £5,000 and it cost £2,000 to repair you may never get your money back, but you could well patch it up and get a good deal of fun out of it and still sell it later for what you paid for it without doing a thing. On the other hand a boat woth £100,000 needing £2,000 spent on it is a different consideration entirely.
 
One of the problems is that once osmosis has been identified the insurance companies insist that it is rectified.
 
I bought a boat with a few blisters 3 years ago. The surveyor recommended a peel and epox. When I took it out the boat yard drilled the blisters with a flat bottomed bit about the size of a 10p. They said the matt coat and laminate were in exellent condition, and I would be wasting my money having it peeled, she was left to dry out for the winter then filled with wests epoxy. The boat is now 22 years old so she comes out every winter, and so far I have not seen a single blister since.
More help here http://www.turbolink.co.uk/jlasurveys/osmosis.html#wicking
 
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