Fiberglass blistering - still a problem on modern boats?

[Rdubs]

Hi all,
Do newer boats (such as mine, a 2013 model year Jeanneau) suffer from blister problems if left in the water year-round the same way older boats do? Or has fiberglass technology improved over the past few decades so it isn't as big a problem as it used to be?

Right now my boat lives in the Bahamas, but for hurricane season, I have two options:

1) Put the boat up up on the hard strapped down for July to November. The advantage of this is that it gives a good 5 months or so for the hull to dry out, so if there is any water which has gotten into the fiberglass and would become a blister, that gives a chance to air out the fiberglass and hold off blistering.

2) Keep the boat in the water inside a protected canal at a friend's house. While relatively safe from hurricanes, the disadvantage is it leaves the boat in the water year-round and so never gives the hull a chance to dry out, so would increase the onset of blistering down the road.

Many thanks for any thoughts.

[roverhi]

Hopefully boat manufacturers have switched to vinylester or epoxy resins which are way less prone to blistering than Polyester. In any case, most of the blistering problems date from the OPEC fuel embargo of the mid '70s. Remember the Polyestermite. Because of a shortage of US made resin caused by the embargo, manufacturers switched to sources from out of country which were way more prone to blistering. There were also problems with fire resistant resins that effected a few boats like Valiant that used it for a short period. Good Polyester resins are not completely free of blister issues but it usually so small a problem that it's a small issue easily handled at bailout.

Wouldn't be all that concerned with leaving the boat in the water. My '76 and '69 boat have been in the water continuously for their entire lives with little to no blisters. Wouldn't worry about keeping the boat out of water if you've seen no signs of extensive blistering. The gel coat for the most part is a water barrier and the absorption of water for a normal polyester lay up is minimal at the worst.

[Suijin]

Originally Posted by roverhi

Wouldn't be all that concerned with leaving the boat in the water. My '76 and '69 boat have been in the water continuously for their entire lives with little to no blisters. Wouldn't worry about keeping the boat out of water if you've seen no signs of extensive blistering. The gel coat for the most part is a water barrier and the absorption of water for a normal polyester lay up is minimal at the worst.

Are your boats barrier coated, under the antifouling?

My understanding is that it is still a problem if your boat is not. Certainly it depends on what was sprayed in the mold.

Last time I hauled out, about a year ago, I was next to a late model Jeanneau that the owner was taking down to the gelcoat. It had nothing on it but antifouling and he had a blister problem. It was not terrible, but his philosophy was to fix it now before it got worse and barrier coat it. I don't recall the exact age or model. It was a boat coming out of charter that he had bought from the original owner.

It's probably worth contacting Jeanneau to get some specific information about how your hull was constructed.

[coopec43]

I agree with Suijin.


All boats that are left in the water have to be barrier coated to a certain (can't recall what it is) thickness. My barrier coat supplier specified 5 rolled on coats and it has to be put on in a special way. The first coat of the anti-fouling has to go on while the barrier coat is still "green" for example. If you leave it longer the anti -fouling will not adhere to the barrier coat (there must be a chemical reaction between the two?)

No way in the world will gelcoat stop osmosis.

I used Altex Epoxy Barrier coat and Altex No 5 Anti-fouling which does not require the yacht be put in the water within any specific time. The earlier barrier coats (probably banned these days) required the boat be put in the water within hours of the final coat of anti- fouling being applied

https://altexcoatings.co.nz/frontend...458&marketid=0

[Suijin]

Originally Posted by coopec43

I agree with Suijin.
My barrier coat supplier specified 5 rolled on coats and it has to be put on in a special way. The first coat of the anti-fouling has to go on while the barrier coat is still "green" for example. If you leave it longer the anti -fouling will not adhere to the barrier coat (there must be a chemical reaction between the two?)

No way in the world will gelcoat stop osmosis.

I used Altex Epoxy Barrier coat and Altex No 5 Anti-fouling which does not require the yacht be put in the water within any specific time. The earlier barrier coats (probably banned these days) required the boat be put in the water within hours of the final coat of anti- fouling being applied

https://altexcoatings.co.nz/frontend...458&marketid=0

Just to clarify some of this...

Barrier coat is epoxy, and best practice is to "hot coat" as many of the coats as possible. In actual practice, you put on all but the last coat before the previous coat has cured to hard, providing as you mention the chemical bond. Then you sand it fair, with enough tooth to provide a good mechanical bond with the last coat. The the first coat of anti fouling should be hot coated on the last coat of barrier to reduce the risk of it chipping off down the road.

No barrier coat ever required that the boat go in the water within a certain period. Most hard antifouling paints (as opposed to ablative paints), DO require the boat go in the water within a certain period or oxidation will degrade their performance.

I took my boat down to the old barrier coat a few years ago, to get 27 years of ablative paint build up off. For good measure I then applied 7 coats of of Sherwin Williams commercial marine barrier coat, all hot coated. Let it cure, sanded it fair, then put on a final layer of Pettit barrier coat and hot coated Pettit Trinidad on top of that. The SW barrier is 1/3 the cost of the Pettit barrier, but it's a good idea to have your last coat of barrier be the same brand as the antifouling you're putting on for the sake of compatibility.

[coopec43]

Suijin

I said "The earlier barrier coats (probably banned these days) required the boat be put in the water within hours of the final coat of anti- fouling being applied"

I should have said the earlier anti-fouling coats....

I did mention to an experienced yachtsman that the Altex anti-fouling I was using was "multi seasonal" meaning it lasted longer than one year. He said "you are pushing your luck because the yacht should come out every year"

Cheers

[scallowayuk]

it was caused partly by the binder used in the glass mat. pva was used and moisture wicked up the strands because pva is not waterproof.i believe they still use it .also caused by bubbles caused by not penetrating well when building.clear hulls below the waterline help eliminate this

[Happydrv]

My '95 Catalina had a lot of blisters last winter. PO said he had hauled twice and both time they fixed "a few" but I suspect they didn't look too damn close...
I didn't barrier coat the hull because I could not verify it was dry enough. I did the keel and rudder. Watch out for yards doing that work as I watched them put on as few as 3 coats so they met the owner's budget but it was only about half the correct coats. Mils are more important that number of coats but err on the safe side if you can't measure.

[Mike Banks]

One mistake some people make is to finish the inside of a polyester hull with an epoxy or vinylester finish which is pretty much impervious to anything. That forces any molecules of water in the hull, or of any other un-linked chemistry, to exit via the gel coat in the form of blisters.

Hulls built using chopper guns and mixing the resin and catalyst as they go were notorious for including atmospheric moisture as the spray passed from the gun to the mould.

My take on it--I have seen the results first hand on a boat they was moored alongside. It was covered above and below the waterline in small blisters, which contained liquid when broken open and sanding off.

[goodoldvega]

Funny how all those old boats which have been around for 40+ years suddenly need to be completely re-engineered, isn't it? How on earth have they survived this long without all these experts and their wonderful new (expensive!) fixes?

[ferrailleur]

my boat is not new (1985 Catalina 27) - cheaply built production boat using inferior material -
Anyway, I discovered tons of blisters after hauling out and soda blasting. I grinded probably 95 % of the blisters.... some are still minuscule inside the laminate. I hope they die (!) or I'll get them next year.
After all this very hard work and hoping the hull is dry (7 months on the hard) I finally did the following:

- apply five coats of Interlux Interprotect 2000 (following the instructions)
- apply two coats of Interlux Micron CSC (as above)

I hope that my hull will thank me someday for the effort!

[ferrailleur]

Originally Posted by Mike Banks

One mistake some people make is to finish the inside of a polyester hull with an epoxy or vinylester finish which is pretty much impervious to anything. That forces any molecules of water in the hull, or of any other un-linked chemistry, to exit via the gel coat in the form of blisters.

Hulls built using chopper guns and mixing the resin and catalyst as they go were notorious for including atmospheric moisture as the spray passed from the gun to the mould.

My take on it--I have seen the results first hand on a boat they was moored alongside. It was covered above and below the waterline in small blisters, which contained liquid when broken open and sanding off.

Please comment on my post below.... did I do it right? Don't hesitate to criticize!!

[ferrailleur]

Originally Posted by Happydrv

My '95 Catalina had a lot of blisters last winter. PO said he had hauled twice and both time they fixed "a few" but I suspect they didn't look too damn close...
I didn't barrier coat the hull because I could not verify it was dry enough. I did the keel and rudder. Watch out for yards doing that work as I watched them put on as few as 3 coats so they met the owner's budget but it was only about half the correct coats. Mils are more important that number of coats but err on the safe side if you can't measure.

That's why I went on five coats! Plus extra brushing here and there... Please comment on my post below.... don't be shy... if you don't like what I've done.. Say it! Thanks

[mowerandy]

My hull is a 1974 Australian build (by Seahorse Yachts - Sydney), has not been well looked after by any means (hauled out every 2-5 years) but has no blistering whatsoever. I have seen plenty of other boats of similar age riddled with blisters. It may be that Seahorse sourced a better quality resin, but I lean towards the quality of the lay-up environment as the most likely reason - when I was on the back end of a chopper gun daily in a previous life, the boss was always fastidious about temperature and humidity....


The guys from the fit-up shed next door used to carry the jacuzzi shells we were building through the lay-up bay as we worked...and we would lay up their legs as they went past trying to hide behind the finished shells (then lock the back door before they could put down their load - we learned some cool new words from those guys)….

[BruceS]

mowerandy if your boat has been "down South" most of it's life it most likely will never have a problem.
I bought a boat thatr lived most of it's life up in rhe Witsunday region (warm waters) and it had to have the same treatment as that boat in the pics above.
I'm not saying it wasn't done properly (the one above) but I removed all gelcoat and ground out EVERY bubble I could find/detect. Many hundreds!
I filled & faired with epoxy resin mixed with balloons to a paste (several times!).
Warmer waters will speed up any osmosis as will lack of barrier coat.

Osmosis is not terminal .... just hard work. Bought at the right price & it's a good buy!