Show us your blisters

These are on a boat next to mine in the yard.

Dave, I'd move my boat just on the off chance that those ugly blisters are catching!

Based on the swiss cheese look of the gel coat...mine looked like that....

I would take off all the gel and matt underneath. Check for hydrolyzed laminates...then put on a new bottom.

Just filling those blister holes may do little or nothing for much more serious damage.

psneeld said:

Based on the swiss cheese look of the gel coat...mine looked like that....

I would take off all the gel and matt underneath. Check for hydrolyzed laminates...then put on a new bottom.

Just filling those blister holes may do little or nothing for much more serious damage.

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I’d think that’s a candidate for a “peel” some of those are a 1/4” deep.

That looks worse than 1978 uniflite made out of fire resistant gelcoat.

dhmeissner said:

These are on a boat next to mine in the yard.

View attachment 73008

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That looks like the wall behind the St. Valentine Day massacre. The one in Chicago.

tiltrider1 said:

That looks worse than 1978 uniflite made out of fire resistant gelcoat.

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That’s what our shipwright said.

I looked at a 42’ Uniflite that was worse than that. The broker said it had a minor blister problem...

It looks like it is infectious.

How old is your boat? Looks like a teenager lol

L

Yikes! What else can I say?
Jim

W30 Blisters

Every few years I need to tend to quite a number of blisters the size and number as you can see in the pics. I've done this several times taking less than a day to fix. I grind out each little blister w my small had grinder to a depth of about 1/8th". Then fill the depressions w Epoxy. Had trouble the last time w too much hardener. Only had a minute or two to work as the epoxy would start to smoke and get very hot. I picked the wrong hardener thinking "in Alaska I'm going to need fast acting stuff. I consider the blister "problem" far less annoying than the AF painting and fowling of the bottom. I do that twice as often and at greater expense. Before someone asks I haven't bothered to determine if the blisters occur in the same place upon each outbreak.

Three pics,
!. The typical blister
2. Most of the below the WL was about this concentration re numbers.
3. The completed job before AF paint.

Wow dhmeissner a chill just went down my spine. Looks like Beirut

Lou_tribal said:

How old is your boat? Looks like a teenager lol

L

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Not mine. I’d say the boat is between 30-40 years old. I’m not going to reveal the make. Some of those blisters are 3” in diameter.

Heck, looks like my 1988 Albin 40 did after I sanded the bottom paint off all the way.

Spent most of her life in S Florida in a warm canal...which doesnt help and never had a dryout period...didnt come out for many years between paint jobs.

Surveryor mentioned blisters, but also said most were probably bad paint as they got smalker at the end of the haul period.

He like most must not have understood hydrolysis.

Fiberglas blistering is somewhat of a mystery as some do and some don't. It's hard to go back 30 years and determine if it was the formulation of the reside, too much catalyst, etc.

I first ran into this on a small sailboat in 1981. The correct fix cost was more than the value of the boat.

Fiberglas hulls leak, just very slowly.

The above pics emphasize the need for a good hull stippling now and then (every ten years?) to check on the hull.

In my area a soda blasting costs about $80/ft.

The layers that have failed have to be ground off. That pic at the top shows more than gel coat failure.

The removed layers have to be replaced. Tricky doing on a hull bottom. Sometimes they lay the boat over on its side.

Then you still have a mess, as the new layers are not really that smooth, so the hull has to be faired out.

Once you have a smooth hull again, it's time for a 4 or 5 coats of epoxy sealer before bottom paint.

Around $12,000 for a 40 footer if you have minor holes or blistering. I suspect the OP pic would be substantially more.

the experts I believe that have the big picture, seem to think its the matt under the gel, on top of the rovings that is the evil spirit that wicks the water the fastest into a hull.

So I ground it all off before any repairs started.

I guess I have been lucky. A dozen fiberglass boats, and not a one with a serious blister problem. Worst was a Cape Dory that had three small ones, quarter sized, and one big one, about three or four inches in diameter. Last haulout, I had three or four, thumbnail sized.

my 1977 Cape Dory ketch, hull no5 IIRC, had blisters all over one side...

another South Florida boat all its life... hope someone is getting the picture.... most even in the boating industry dont.

I thought blistering became well understood many years ago.

Polyester resin commonly used in fiberglass construction is NOT impervious to water. Very small amounts work their way into the material via osmosis, hence the term osmotic blisters. The water reacts with the resins to create the blisters and the stinky goo in them. Time in the water vs time hauled is a factor in the degree of blistering, as is water temp. Warm water with year round in the water is the worst.

The solution in equally well understood. Use a truly water impervious outer layer on the hull. Epoxy resins, and others are not subject to osmotic uptake of water. Some builders layup the outer layers with such a material. And using an epoxy barrier coat on the bottom is always a good idea too.

psneeld said:

my 1977 Cape Dory ketch, hull no5 IIRC, had blisters all over one side...

.

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My '88 Cape Dory 28 was peeled and 14 coats (!!!) of Interlux applied back in 2004. (previous owner who spared little expense on the boat) . Dunno it's condition at the time of the peel, but assume it needed it at a cost of $8K ++. Fresh/Brackish water all it's life. All good now of course..

I believe vinylester is used for the final layers on some production boats and is claimed to be waterproof. Costs less than epoxy, and can also be used for repair work.
Recurrent blisters likely occur at fresh areas,I doubt the areas repaired with layers of f/g mat and epoxy or vinylester fail again.

nope...you can have a hull seriously hydrolyzing and delaminating without blisters.

thus my comments that it is still widely misunderstood....

epoxy and vinylester are not impervious and even those fortified with mica and whatever else is still not impervious.

then there is water absoption from inside the hull if wet caising hudrolysis and blistering.

psneeld said:

then there is water absoption from inside the hull if wet caising hudrolysis and blistering.

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Good point. Epoxying bilge areas where water might accumulate is prudent....bilge pump sumps, for example.

No one likes a girl with zits ,

but has there ever been a documented case of a boat being sunk by blisters?

In most "fixes" I have seen ,,I think far more damage is done to the hull structure from the cosmetic "repair".

blisters are not the problem....they are or not a sympton of hydrolysys and further delamination of layup.

no boat has sunk that I know of from it .

In my readings and research, I have read that more than a few boats haved failed survey, mine should have and probably would have on the next one.

Here is but one, multiply by thousands of surveyors.... so no, not a common problem.... but an issue if you miss it or ignore it.....

http://www.boatsurveyor.com/blistered-sister/

I have only looked at two vessels in the previous nineteen years of surveying that I told the prospective buyer had serious enough delamination problems to warrant invasive testing to ascertain and verify structural integrity before purchasing. Both vessel’s had severe blistering that had led to gross delamination affecting the structural integrity of the hull.