thousands of bottom blisters

[Old fella]

Originally Posted by Jmstee

Thankyou for all the suggestions Im going simple; sand now then barrier coat in the spring and repaint. Then pretend there was never an issue and enjoy sailing.

That's it mate, you got nothing to worry about, the boat will out live you, cheers Brian.

[Cadence]

Originally Posted by Old fella

That's it mate, you got nothing to worry about, the boat will out live you, cheers Brian.

Amen!

[KASHMIR]

Originally Posted by Peter O

I feel for you having gone through the same issues recently.


I used 7 layers of barrier coat.and some of the tiny holes only started filling after 5 layers.
It is very important that you apply one layer of bottom coat immediately after the last layer of barrier coat while the barrier coat is still a little sticky. Once the barrier coat is dry the bottom paint will no longer stick.
Good luck!

I am at the same stage with my boat, I barrier coated it ten years ago after taking the gelcoat off. This slip the blister are back, and loads of them. I have once again stripped it back to glass layup. I am drilled out most of the blister and given the boat a few thorough wash downs that makes more show up. I will epoxy fill them and fair. I am not sure which way to go from there? Do I go with 5 layers of interprotect? Which I suspect is what I used last time or do I go with the west system method which I believe is about 7 or 8 layers? Then I suppose I let that cure, prime paint with something like International Primecon and anti foul. What have been people experience of the various methods?

[vic008]

Osmosis in yachts yeah, but have never heardof in launches. Why is this?

[admiral 31]

As a retired boatbuilder & repairer with nearly 30 years of experience (working mainly with fiberglass boats) Given the age & worth of your boat & the fact you do not want to spend a fortune on this.
I would suggest that you just sand the underwater hull smooth, then fill any blisters which break through with a polyester (not epoxy) filler, repaint & antifoul & have another look next time the boat is out of the water.
it is what I would do on my own (1980) boat
btw, in all my years I have never heard of a boat sinking of osmosis!
but no doubt someone on here will have!

[Uncle Bob]

Originally Posted by double u

“Maybe it's a little bit of knowledge is dangerous.“
Which “knowledge“? “Epoxy catalyst“?
I am increasingly irked by people writing their wild-assed assumptions as the gospel truth.

Love this comment. Sailing for Jesus and gospel truth.

[DeValency]

Originally Posted by Jmstee

I started sanding about 24 hour after haul out and found thousands of tiny blisters that start to show as the paint wears thin. I ground a few out and they don't seem to go past the gelcoat. there is only a trace of moisture in them as well. How would you recommend repairing this. its an old boat and the budget is small. I want to prevent further damage as much as possible. Part of me thinks I should leave it be and let it dry for the winter then barrier coat and repaint in the spring. It just doesn't seem possible or wirth the time to grind each spot. Thoughts?Attachment 202056

Sanding the entire bottom and recoating, considering the blisters are not under or inside the laminate but only the paint isn’t a pricy job. Sailors do it all the time even when there are zero blisters as a good housekeeping.

At any case you don’t want to carry with you the blisters and any boat need a good barrier/primer - follow the instructions related to the time between applying the barrier and the anti fouling- most brands require a very short time in between- hours or light sanding of the barrier/primer before applying the anti fouling. Keeping these instructions in mind should prevent future blisters.

[garyfrankovich]

Is it possible that it's an old barrier coat blistering, this is quite normal after 12-15 years, regardless, if it's an older boat, and your budget is tight, I recommend that you just ignore them, sand and bottom paint as usual, and go sailing. There is not a single case of a boat sinking due to blisters. If they're as numerous as you say the only Possible fix is to strip down to laminate, let dry, and then barrier coat. Prohibitively expensive for an older boat.

[jedocrat]

From previous similar experience a few years back with a Tralaren 8.4.
I sanded the hull using a rotary sander and 60 grit opening all the blisters. Left her to dry over the winter, about four months. Sanded again using 80 grit till it was reasonably smooth. Using a short haired 100mm roller Applied two coats epoxy primer and three barrier coats allowing a day between each coat. After all that it was two coats of ablative anti fouling. A good finish and still going strong. Peeling and reapplying the gel coat just isn’t an economically viable option and just doing a cosmetic touch up is like makeup on a wrinkly skin, nice from far but far from nice!

[Giro]

If it means anything to you, my boat was in dry dock for over twenty years and had the same blisters in the gelcoat. I had her gone through in a boatyard and spent more money than I care to admit to reach a near “restored” condition. The one thing the professionals told me was not to worry about the blisters in the gel oat. They buffed the entire hull, bottom painted it with two or three coats and called it good. I’m told that there should be no problem whatsoever. I guess only time will tell, but she looks like new.

[gulfislandfred]

Had this pretty much identical on an old Morgan Out Island 41. When I sold it, the buyers surveyor had me grind a small area so he could see what was underneath. I did that. He looked, and confirmed that the blisters were just into the gel coat and where it met the first matt. No problem. Paint it, and don't worry.
You get a chance to check it every year or two, when you haul out. If there is damage, it happens slowly.
Most glass hulls are more or less saturated with water. Newer boats, not so much, but lots of fine older boats are not barrier coated, and they last and have lasted a long time.
Slap on some paint to keep the hull smooth (from critters), pressure wash and examine at haulout, relax, and go sailing.