How common is Osmosis

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Kendal

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While looking for my first boat, I have come across the ideal one at the right price (1996 american 25ft cruiser). Only problem is, it has minor osmotic blistering. Having read various opinions on the subject, I was wondering how common this is. Should my search continue?
 
Carry on looking. The right price, American, osmosis, all terms to wary of. The rule of looking for a boat is the ideal boat is always too dear.
 
[ QUOTE ]
While looking for my first boat, I have come across the ideal one at the right price (1996 american 25ft cruiser). Only problem is, it has minor osmotic blistering. Having read various opinions on the subject, I was wondering how common this is. Should my search continue?

[/ QUOTE ]

It is very common, if you are sure it is what you want, and it is the"right price" knock another wedge off it to be sure and go ahead.of course only you can decide as you have not given us details of make or actual price!!
 
Blisters do not always mean osmosis ie. a breaking down of the fibreglass laminate, it may be wicking (moisture between matt coat and gel coat) however as its only 10 years old it does not sound too good.
 
Vertually all fibreglass built boats will have osmosis in one form or another.
Especially the older ones that were laid up in damp or uncontrolled conditions.
It is caused by the styrene that is used in the original layup process.
Styrene absorbes water by natural process and styrene is in the resin that is used in the layup.
It actually draws the moisture through into the weave of the hull.
This is then trapped behind the gelcoat and in pockets in the fibreglass, Causing a chemical reaction and the blistering that you see.
Sometimes it does not blister and just causes a high moisture count.
It can also cause all sorts of other problems too detailed to go into here.
Modern boats that have been laid up in controlled conditions or use newer more high tech gelcoats and resins fair much better but can still suffer.
Get a surveyor to check it out if in doubt.
Cheers
Joe
 
depends how you define old fibreglass boats. Actually the really old fibreglass boats are very unlikely to have osmosis. This was a feature following a major price hike of the resins, that saw the introduction of inferior resins into the boatbuilding trade. Most 10 year old craft dont sufer as much cause better resins are now being used, however you are less likely to get such a thick lay-up so the hull will be less able to withstand point impacts.
 
Lots of info about osmosis here.

I suspect a surveyor will recommend a gelcoat peel, dry off for several months then epoxy treatment, simply because if he says it's unlikely to be a big problem and it turns out to be he'll get sued, but if you spend gazillions putting it right and it doesn't cure it, it's the boatyard's fault.

I'm no expert - my 35 year-old boat didn't have any blisters last time I looked - but from what I can gather, lots of small blisters (<1cm dia) are less of a problem than one or two soup plate sized jobs. Generally, the biggest problem with blisters is that the surveyor will say an expensive treatment is necessary and your insurance co will insist that it's done before they'll cover you. Plus, a lot of potential buyers will walk away and those that are still interested will expect a LARGE drop in price. It's up to you which you are, but I think I'd walk away from that one unless you really can pick it up for a song. That's not an old boat and blistering tends to get worse as time goes on.
 
If it's showing blisters after 9 yrs then don't touch it with a barge pole. It's an extremely good indication of an incredibly bad lay up on such a young boat.

If you won't listen to reason then get a few yards to quote for the gel coat peel, drying out and relamination. Don't be fobbed off by asertions that polyester resin is ok for the repair. It must be done using epoxy and then have the epoxy barrier coat(s) applied to the bottom.
 
No boat ever sunk from osmosis as far as I know, but fibreglass boats are only 40 years old or so.

Its a bit of frightener really, the real problem is the above postings, no one wants to buy it.

It will seriously devalue the boat, but you may well get a good bargain if you are clever, and don't want to resell the boat in the near future.

Mj
 
Agree with Mark. When buying my boat 5 years ago I looked at another similarly priced, with osmosis and was scared off. Found out last year that it eventually sold for 60% of the price of mine - a saving twice the cost of osmosis treatment, and there was no guarantee that the boat I bought wouldn't start to blister the next day; after treatment you get a 10 yr warranty. The downside is the hassle of getting the work done.
Andy
 
Sorry,
By old i mean boats going back 40 odd years.
The really old ones suffer more than the newer better laid up ones with the more modern resins and lay up systems.
But they will all get some form or another in the end, If left for long period's in the water.
Salt water and fresh water boats also absorb at different rates.
Some old boats like Westerly's did go to some lengths to lay their boats up under controlled condition's and used only approved resin's recommended by Loyds but these still get Osmosis.
As mentioned the more modern boats are often very much thinner in the lay up and once the gelcoat is removed can leave the hull very weak.
Can't remember any baot sinking due to Osmosis but i have seen boat's destroyed by stripping the gelcoat off!
I would be very carefull of stripping a modern thin hull of it's gelcoat and effecting an epoxy repair to be honest.
The older thicker boats can generally cope well with a strip and dry out.
Joe
 
Got to disagree with you there Joe, gelcoat adds no stuctural strength to a laminate, so removing it will not weaken it.
 
I had a survey done on a boat that I did eventually buy - first surveyor said it had minor blistering on the bow caused by osmosis. got a second opinion who couldn't find any evidence of it at all. Before I bought it I got a quote for a strip and epoxy coat and haggled the price accordingly. Prices from south coast yards were more than double those quoted on east and west coast yards. two years later though there is still no evidence of osmosis or the various other causes of blister effects. also be wary of moisture content readings - highly dubious test method and often done incorrectly.
 
I did not say that it did, Did i?
The gelcoat is just a surface coating and not the strength part of the hull, However, What i was getting at is the fact that the gelcoat stripping process also takes of a layer of the glass fibre, Including the matting and resin.
On a thin hulled boat this can be a problem.
I have seen keels fold up into the hulls and boats belly out due to stripping.
It was just a note and no more.
Cheers
Joe
 
G'day David,

Some points to ponder:
IF you decide to go ahead with this your insurance company will need proof the problem has been attended to. This could take months, so you need to consider the time lag.

IF you have it treated, you need to ensure that only epoxy resins are used and, that a layer of glass is also applied after stripping, followed by fairing with closed cell balloons and only epoxy resin. Then at least 4 coats of epoxy resin followed by an epoxy intercoat prior to antifouling.

You should get some quotes to do the above work and present this to the seller and have the price reduced to cover the cost. If it's being sold cheap "as is", add the cost of the quote and see what you can get at that revised cost, if this figure is outside your budget then keep looking.

Finally, Osmosis is not a death sentence for any boat of any age. Think of as rust on a steel boat, it can be treated and prevented, but not forever. Any fibreglass boat built during or just after an oil shortage is suspect because the resins produced were less than perfect, last time I looked we only had 4 manufacturers in the world, yet we see over 50 suppliers, and each one adds their own potions to 'improve' the basic product.

I hope this helps.

Avagoodweekend......
 
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