Are these blisters

[Bdozz]

Are these blisters or just bad paint, and what's the best repair option

[kmacdonald]

OMG, slap a coat of anti-foul on it and unload it ASAP.

[Souzag818]

I think more information is needed. Where are these located?

[brianlara 3]

Bit hard to tell from the photos.
As a younger man I probably laid-up fifty fibreglass mouldings. And like a lot of people, I've also seen a lot of osmosis blisters.
From the reasonably undefined photos it seems to me that whatever it is you have it sure does not look like any proper blister I ever saw.
I am inclined to think that what you are looking at is simply air bubbles in the paint or the gelcoat or whatever it is we are looking at.
More info such as distance from the lens, lens angle ( e.g. 28mm focal length etc), just what this substrate actually is.....multiple colours and gelcoat is usually white.

Helps to understand just what osmosis actually is. When a moulding ( e.g. a hull) is laid up the mould is actually a female concave ( typically) surface onto which a release agent is first applied. The r/agent is often green brushable of sprayable plastic film in liquid form. As the name implies, the r/a enables the finally laid-up moulding to be easily refoved from the female mould. Sometimes wax is used in lieu of proper r/a. Either is fine.
Next step is: gelcoat is (typically) brushed into the mould ontop of the r/a. Understand now, that gelcoat is usually pretty crappy stuff which, whilst the medium is good polyester resin ( sometimes vinylester) what gives gelcoat it's thickness and opacity is usually TALC...yes, think unscented talcum powder. So gelcoat is good polyester resin with a pretty poor thickener....been happening since the sixties. Probably first used by Vander Stadt in Zer Netherlands.
95% never any problems.
BUT, if atmospheric moisture levels are high when the cloth/fabric/glass is laid-up onto the cured gelcoat then micro droplets of moisture become present as foreign bodies if you like, in between the gelcoat and glass.
Eventually, the moisture gets stressed in it's confinement and starts to expand pushing the gelcoat outwards into a bubble and also the moisture permeates the glass.
Because gelcoat is really only talc in suspension absorbtion of saltwater is common, resulting in blisters.
Beneteau played with tinting gelcoat into hull colours. Didn't work because talc and pigments are a poor mix and in any case, rapid ablation occurs. (Think it was Beneteau).
Using vinyl resin is good but more costly. Best gelcoat of all is self made with epoxy usually as "one -off's". Big dollars!
Many owners often leave their osmotic blisters to see how quickly they grow or don't grow.
I've had some, 2 inches in diameter and 3/32" proud in height for 7 years and the next owner can care but I don't.
What you see is probably absolutely nothing and if they were on my list of important things they'd be #100.
More info would help.
Been a rant, sorry.

[El Pinguino]

Those aren't blisters.... these are blisters..... two cases of severe osmosis.

Your boat has gelcoat pimples.

[kmacdonald]

Originally Posted by brianlara 3

From the reasonably undefined photos it seems to me that whatever it is you have it sure does not look like any proper blister I ever saw.

Specifically, what is a "proper" blister as apposed to an "improper" blister?

The photo above of the red bottom shows blisters. They are the small bulges or circular protrusions. You will only see them for a relatively short period of time after the boat is pulled and that is the best time to check the hull for blisters. You can also find them after it dries but takes a little skill. When you pop them a liquid will come out.

[brianlara 3]

"Proper blisters" and "improper blisters" are similar to syntax and pedantics. Capiche?:

[UNCIVILIZED]

There's nothing in the pics to give a sense of scale, so the images could be those of far off galaxy sized objects for all we know. And it would also help to see images that offer up a bit more optical contrast. In addition to some closeups of the 'blisters', with a ruler next to them. Ditto on ones which show their depth.

[El Pinguino]

Originally Posted by UNCIVILIZED

There's nothing in the pics to give a sense of scale, so the images could be those of far off galaxy sized objects for all we know. And it would also help to see images that offer up a bit more optical contrast. In addition to some closeups of the 'blisters', with a ruler next to them. Ditto on ones which show their depth.

A pic with a ruler to show scale would be nice but on the evidence so far presented I would take a punt on pimples in the gel coat.

The pics I posted were of blisters living deep in the lay up. Second pic was post blister where some onehas had them ground out and is about to do a bog and paint job rather than a proper repair.... buyer beware!... this is a common fix. Owner in question had been quoted about NZ$30K for a proper job.... had chosen a NZ$15K crappo fixo.....

[capt-couillon]

If you puncture a blister caused by osmosis, the fluid that comes out will smell of acetic acid (vinegar). Not so for paint blisters caused by poor prep or other bonding issues.

[Bdozz]

None of them are deeper then the gelcoat, most are smaller in diameter than a pencil and none larger than a dime. Assuming they are gelcoat 'pimples' , how do I fix them ?

[a64pilot]

How old is the boat?
I have "pox" on my boat, biggest are about .25". As crazy as this sounds there were more of them when I bought the boat than there were the last time I pulled it. I pull it again next month and will look again of course.
I was told by a few people that if it took 30 yrs to get some blisters that are .25" max, maybe in 20 more they may grow to dime size and may need to have something done then.
I have decided to fly it and watch it so to speak.
Mine are shallow and do not seem to go deeper than the gel coat, but do have the vinegar smell when you pop them.
PO had the boat stripped and epoxy coated when he had a bottom job done.
I do not believe it was allowed to dry before the epoxy was put on and moisture was then sealed in and these little blisters are from that, they seem to be diminishing, which confuses me, I would have thought they would have grown.

[Bdozz]

The boat is 36 years old, none of the blisters had fluid in them, it was on the hard for 8 years before I bought it early this year, I'm not really concerned about them causing any structural damage as it seems to me none are into the laminate, but I would like to do something with them while I have it in a good place to work on it, and before I put antifoul back on.

[weavis]

From my experience, these are not a concern. A nice rubdown and application of appropriate anti fouling will remove. Im assuming they are on the hull.

[Souzag818]

Are these under the water line or on the topsides? Can't tell...If the boats been out of the water for 8 years, that's good.