Osmosis

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sudsy said..
Just had the broker ring me during the survey, the surveyor has found some osmosis on the catamaran that I have been trying to buy for the last 2 months. She's a 34' American production boat solid fiberglass hulls composite deck . There's a few blisters on the starboard side of both hulls around the centerboards cases and a few on one of the bows . Obviously I want him to confirm how many and if he thinks he has identified all of them. The boat is 155k and is almost the perfect boat for what we want . We are so disappointed . Osmosis can be fixed and I have the experience and the skills to do it . What I dont have is enough experience to know is if it will come back to haunt me later. Everything else about her is what we need. Appreciate anyone's ideas. Any fiberglass gurus out there?

I don't believe that osmosis has ever sunk a boat, negotiate a price considering the findings and repair (you have said that you have the skills) and enjoy the new to you enjoyment machine.

How old is the boat, has it always been in the water for this time or has it spent a significant time dry docked - if so hence a significant input as regards the potential for future blisters, what size are the blisters, assume the layup is polyester not vinyl ester. I have done a full hull osmosis repair on a Black Soo during a week's summer slipping at Woolwich in the mid 80s under cover in their shed - ground out the blisters, epoxy filled, epoxy dynel sheathed the whole underwater area. It worked.

Heaps of osmosis information on line including this useful summary;

www.compositesaustralia.com.au/pdfs/Chris%20Cranitch,%20ATL%20-%20Osmotic%20Blistering,%20Causes,%20Prevention,%20Correction.pdf

Agree with the above conclusions.

I repaired the osmosis in my 1979 UFO 34 myself approx 5 years ago. Sold it earlier this year and there were no issues. If the repairs are carried out properly you should be fine. If you really want the boat factor the repairs as a discount to the purchase price.

Ilenart

As an advocate of Aussie cats I would ask, why go US? I understand each to their own but Aussie cats sail so nicely compared to those produced overseas.

I thought American built boats were generally of very good quality.

Unusual that a relatively young, VE sheathed hull would have Osmosis.

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sudsy said..
There's a few blisters on the starboard side of both hulls around the centerboards cases and a few on one of the bows . Obviously I want him to confirm how many and if he thinks he has identified all of them.

Location of blistering is odd, only on one side of both hulls, If it was on both sides to the rear of the CB cases I would be looking for grounding repair with PE as a possible mechanism for water to enter the substrate.

Please keep us informed of the survey result as to the extent and size. A couple of pictures would be good also, there is a big difference in the repair needed for big oozing degraded laminate compared to gelcoat aeration voids.

I suppose what you are really concerned about is will more appear and how frequently. If the boat only has a few after 12 years ( and no previous blister repair ) then you could expect similar in the next 12 years, hard to say really as you have direct evidence of some deficiency in the barrier coating. Perhaps factor into your costing you may want to do a full barrier coating in 4-5 years time ( just before you sell it! ).

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lydia said..
There a pics on the what did you do to your boat today thread

Thanks lydia, any idea where in the 165 pages

I would be thinking, what's it worth to you to secure this boat? You have some 'strict' criteria (as you should) and after years of looking you have found One that ticks the boxes... You have also said you are capable of building a boat. I would think fixing this issue would be child's play for you and not particularly expensive. Do you want to spend a few more years looking, or get this at a good price, fix her to a standard you are happy with and go sailing sooner rather than later....

Thanks Toph , it's not exactly child's play , to properly fix osmosis if it's extensive you have to remove all the gel coat, **** of a job ,then basically reglass her in epoxy . It's not just that though , the boat was marketed to me as being fastidiously maintained and serviced , because of covid I haven't been able to look at her myself, which is no big deal because I've owned boats my whole life and have the excellent resource of a really knowledgeable forum in the States dedicated to these boats alone . As I said she ticked nearly all the boxes for me , but build quality and a couple of other things that weren't major weren't ticks. But buying a boat also has an emotional element, for a few reasons it's taken nearly 2 months to get her to the survey, during that time I have armchair sailed her all over Bass Strait and Tassie and had many great adventures. Then all of a sudden she's not what you were told and you're rational side kicks in, there is an element of disillusionment it all feels a little tainted . I know it's a first world problem.
Uncle Bob, yourself and couple of others are saying go for it after negotiating something fair and that's the way I'm leaning but these decisions aren't easy . I've been advised to stay off Forums because they can mess with your head, but I like to get lots of input before I make major decisions. Anyway I will keep you all in the loop

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stray said..
A mate of mine recently had to sandblast grind and add a layer of glass back on to a benno that looked a lot better than that does.

Thanks stray

we had to have some osmosis repaired a few years ago on our previous (aussie built) cat.

done professionally and wasn't all that expensive...although that is likely to be a matter of perception.

one issue is that you can only fix the spots that are apparent at the time. however more will develop over time unless you strip back the entire hull and re-coat...which is rarely worth doing.

we fixed the spots that had been found and sold the boat not long afterwards

cheers,

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PacificStar said..
we had to have some osmosis repaired a few years ago on our previous (aussie built) cat.

done professionally and wasn't all that expensive...although that is likely to be a matter of perception.

one issue is that you can only fix the spots that are apparent at the time. however more will develop over time unless you strip back the entire hull and re-coat...which is rarely worth doing.

we fixed the spots that had been found and sold the boat not long afterwards

cheers,

Thanks for your input, PacificStar
Cheers

In the next 12 months when the economy really hits there will be bargains everywhere, real bargains unfortunately desperate people