teeeeny tiny blisters--above waterline

[defever]

i've got a 41 defever trawler (1983) which was laid up heavy w/ more than normal layers of glass. after 17 yrs i started getting thousands of tiny blisters along the fake-strake lines. 3 yrs later they started to ooze a rust-looking goo. only way to clean it is w/ oxylic acid---lasts 3 wks-3mos. assume it's styrene or something from the glass layup. anyone got any bright ideas??

[knottybuoyz]

Got any pictures defever? Sounds like typical osmosis problem if they're weeping. There was a similar age and size Marine Trader in our yard a few yrs ago with the same problem. Solution was to route out and fill each one then repaint. Not a small undertaking if the problem is widespread.

[defever]

assume it'll just be a cosmetic issue...haven't got the $$$ to pay to fix and w/ thousands of blisters ( and i'm 60) not enuf time...

[denmanislander]

Hard to say if these are the same but just had a survey done on my fibreglass 10 m Cooper Prowler and it had the same thing. The surveyor from Meadows Marine in Victoria, BC, said that he thought they were a reaction from the bottom being painted over a type of paint that was previously used to cure blisters. It sounds a little confusing but the official word on my blisters was cosmetic, don't fool with them unless they pop when sanding the bottom for new paint, then sand smooth and paint.

[Talbot]

if they pop, then you do need to do something, or you are letting water into the the area below the gelcoat. This can wick around the inside of the hull and create a massive osmosis problem. If the hull is a solid construct, this is no so significant as a cored hull, where it would lead to delamination. I prefered to grind out the blister, wash it clear of the styrene (or whatever) let it dry and then fill the hole with an epoxy filler.

[roblanford]

How far above the water line?

[defever]

from the scum line to the toe rail

[Pblais]

from the scum line to the toe rail

With 41 ft of a Defever you could have a lot of them. I suppose it has a chickenpox look.

They may not be significant other than the look. That alone may be enough to warrant curing the disease. I would do a test on an area that is the least obtrusive and perhaps exhibts the problem the worst and dig them out and go through the process of filling and see the results of how deep they go and how long it takes. Doing a few dozen is not hard but you sure wouldn't take on 1,000's without some idea of exactly how bad it is. The seriousnes is under the spots.

Fixing them all is a lot of labor. It's not hard but exceptionally tedious. It's expensive to pay for it by the hour and a very long period doing it yourself. If only cosmetic then you can make your own schedule for getting it done or doing it. Even cosmetic is tends to make a problem that makes it hard to sell the boat later.