Thoughts on Blisters

Phil Fill said:

We pressure wash, sand and break/grind the blisters as we come across them. Most of the blisters are small dime size and a few quarter which are surface blisters. Pettit Trinidad is epoxy based so it dries hard to form a protective barrier. However, if left to thick the bottom paint will blister. That is why we lightly sand the hull. Same idea as sand between coats when varnishing/painting so the paint sticks.

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.....clearly the mad raving of an "internet heckler".

Besslb said:

We would powerwash, acid wash and do a decent job sanding and feathering in of flaking paint, getting a smooth-ish surface to paint on. Then three coats.

So, looking at this from a different angle....is there any reason to "not" sandblast all of that old - thick - layers and layers of paint off, get 2 coats of barrier epoxy and start with new paint? Having the biggest blisters ground out while they're visible.

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I was working on a bottom job once and a steel boat was next to me being sand blasted. I wondered about sand blasting my bottom and asked the guy to hit it with his sand blaster. Sorry I did that. He only did about a few square inches. It not only took the bottom paint of but to the gell coat and beyond. Soda blasting could be an option or crushed walnut shells or some other soft abrasive could work. Just don't use sand.

SD

skidgear said:

.....clearly the mad raving of an "internet heckler".

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Cute...my point is knowing the whole problem...people who put band aides on their bald heads sometimes die of melanoma...

You response is typical of just those I was referring to....

psneeld said:

Cute...my point is knowing the whole problem...people who put band aides on their bald heads sometimes die of melanoma...

You response is typical of just those I was referring to....

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Rest assured that most folks understood your point a long time ago.

do it right or leave it alone! half azzed patch jobs lead to greater problems later.

Just have her hauled and get to work. Cheapest and best way cause then u know eactly what was done. Hopefully your bottom has never been "repaired" by a know it all before and u can proceed. Get her down to the gel coat and start grinding out the blisters till there all opened. dry the hull with tarps and lamps. when you think its dry dry it some more then fill in the holes with a product compatable with the type of glass your boat was made of. Sand her down smooth then coat with at least four layers of a barrier coat exactly as specified by the manufacturer. Bottom paint and forget blisters forever. Ive used interlux before and that stuff is like iron but very hard to apply in a smooth coat because of its low solvent content.
I'm not a professional just had blister concerns a couplke of times over the years

Besslb said:

Hi TF People!

Everyone in Sandy's path stay safe. (not the question)

What are your thoughts on blisters? We know we have some. It's one of the reasons we haul and paint yearly. When we surveyed originally the bottom was very bumpy and the surveryor said that it would need doing eventually. PO hadn't painted the bottom in the 4 years he owned the boat. Since our yearly paint jobs, the bottom has improved quite a bit.

We're hauled at a new yard, and of course the yard manager wants to talk about our bottom. We're going tomorrow to see her and see if it really looks any worse than it has in the past couple of years. (Tom was in a little bit of a hurry when he delivered her there, and didn't make a point of taking notice other than the previous paint didn't look so bad)

The full peel is out of the question financially. But what about sandblasting back to gelcoat and an epoxy barrier coat? What are your thoughts on that job. Is it worth it? Does it fix the problems or is it just a stop gap on the road to the a peel?

Thanks ya'll!!

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bfloyd4445 said:

do it right or leave it alone! half azzed patch jobs lead to greater problems later.

Just have her hauled and get to work. Cheapest and best way cause then u know eactly what was done. Hopefully your bottom has never been "repaired" by a know it all before and u can proceed. Get her down to the gel coat and start grinding out the blisters till there all opened. dry the hull with tarps and lamps. when you think its dry dry it some more then fill in the holes with a product compatable with the type of glass your boat was made of. Sand her down smooth then coat with at least four layers of a barrier coat exactly as specified by the manufacturer. Bottom paint and forget blisters forever. Ive used interlux before and that stuff is like iron but very hard to apply in a smooth coat because of its low solvent content.
I'm not a professional just had blister concerns a couplke of times over the years

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only taking it down to gel may be a "half azz job" in itself without further investigation...

psneeld said:

only taking it down to gel may be a "half azz job" in itself without further investigation...

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yes, to be done before the first blister is popped

I owned a 73 Uniflite... just before Uni's blister problems really became a BIG deal throughout the brand. Owning a 1977 Tollycraft there is not a blister in sight and no other Tolly owners I know have any either. Good luck with blister repairs. Yea Tolly Boats!

Art

Not too fast now. Some years ago I made an offer on a 1988 Tolly 44. During survey over 100 blisters were found between a dime and quarter in size. Running from that vessel I had a 1992 Tolly 48 go through survey. There were about 20 good sized blisters around the struts. Walked from that one too not only due to blisters but FRP issues in the side decks. I love Tollycraft but they are not free of FRP issues..

sunchaser said:

Art

Not too fast now. Some years ago I made an offer on a 1988 Tolly 44. During survey over 100 blisters were found between a dime and quarter in size. Running from that vessel I had a 1992 Tolly 48 go through survey. There were about 20 good sized blisters around the struts. Walked from that one too not only due to blisters but FRP issues in the side decks. I love Tollycraft but they are not free of FRP issues..

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That may well be true for late 80’s and 90’s Tollycraft... reminds me of Uniflite boats; in that mine having been a 1973 model was the last year before Uni began to experience blisters from mid 1974 onward for many years due to resin mix alterations. So... our 1977 Tolly and other Tollys I know with no blisters are all in early 70’s to early 80’s. Might be that during later years Tollycraft build-outs also utilized FG materials that would eventually blister. But, our 77 Tolly and the other Tolly owners I chat with who own older Tollycrafts experience no accountable blisters that I know of.

Before 73 , when the Arabs and Jews had a tussle and the price of resin went from 13c a pound to almost a buck, a blister GRP was the result of a dirty shop ,or very poor workmanship.

Most resind became crappy and blister prone immediatly.

Due to the industry and USCG requirements FR (fire retardant) resin took a few more years to become crap.

So Uniflites and other boats built for inspected vessel service , or Unkle Sam were OK till 76 or 77.

so only old boats are good? i thought the problem had been pinned down to the use of to high a solvent content? solvent was added to make it easier to apply and a smoother finish. the modern epa standards for low voc plastics should result in very few blisters as long as the applicator dosent add solvent.

bfloyd4445 said:

the modern epa standards for low voc plastics

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The overwhelming majority of these boats are being built far away from the influence of the EPA.

CPseudonym said:

The overwhelming majority of these boats are being built far away from the influence of the EPA.

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and thats why half azzed repair specialists this with solvents. the finished products looks better but wont last

solvent was added to make it easier to apply and a smoother finish.

Resin is sold commercially by the pound , and retail by the gallon.

The solvent was added to take up space , instead of expensive resin.

Boats that were hand laid up by a small crew seldom had hull problems,

The use of a chopper gun to cover the fresh gel coat , to stop fabric bleed thru , is the cause of most surface blister problems , the thinner was trapped befoe it could evaporate.

Better shops used 3/4 oz CSM instead of chop, and had no problems.

bfloyd4445 said:

so only old boats are good? i thought the problem had been pinned down to the use of to high a solvent content? solvent was added to make it easier to apply and a smoother finish. the modern epa standards for low voc plastics should result in very few blisters as long as the applicator dosent add solvent.

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There's way more to the hydrolysis and blistering story than just bad resins and poor application...lot's of great reading out there outside the marine industry...

Search for GRP tank and piping issues...that industry has done some interesting research into the hydrolysis of GRP and what conditions accelerate it.

UPDATE - We visited Skinny Dippin' today to check on progress and deliver tools for refinishing the salon floors next weekend.

The media blasting has been finished ($1500) to remove all the years of old paint and open up the blisters. At first, it looked pretty bad, but most, if not all, of them are cosmetic. We knew that going in. None seem to be weeping and the hull looks pretty good. We are going to let it sit for another three weeks before applying three coats of Sea Hawk barrier coat and two coats of hard bottom paint.

We discovered a few previous repairs and they still look solid. The yard owners is also pleased with the results and says that the results we see are typical and we are still on time and on budget.

Here are the new pics:


P1020035 by GonzoF1, on Flickr


P1020033 by GonzoF1, on Flickr


P1020032 by GonzoF1, on Flickr


P1020031 by GonzoF1, on Flickr


P1020028 by GonzoF1, on Flickr


P1020034 by GonzoF1, on Flickr


P1020036 by GonzoF1, on Flickr


P1020044 by GonzoF1, on Flickr


P1020043 by GonzoF1, on Flickr

Gee...looks like my bottom did...brave enough to put a chisel to some of those deeper spots?????

I wound up pulling 3 layers laminates deep...if you are willing to dig further....

The lack of weeping is encouraging.You look like getting off lightly with a good result.
Mine wept,some until well ground back. I wept too when I got the bill.

Some severe damage doesn't even involve weeping...the laminates may be dry already but already hydrolyzed and separated.

So how can I tell and what questions should I ask now that we are this far into it? What basis and parameters do I make the next decision?

GonzoF1 said:

So how can I tell and what questions should I ask now that we are this far into it? What basis and parameters do I make the next decision?

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Tom: What's the yard say? How about giving Rob Eberie a call and ask him to take a look the next time he's at the yard. I wouldn't think it would cost much and his opion is one that I could trust.

double post

GonzoF1 said:

So how can I tell and what questions should I ask now that we are this far into it? What basis and parameters do I make the next decision?

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When your blisters are ground out, can you get a sharp chisel point into some of the layers?...if they separate / peel off with relative ease...I'd keep going...of ask an expert to take a look.

I kept going (at least 2 trash cans full of matt and roving I was able to peel/chisel off) before finding meat all around....if it all seems solid...you might be good to go. I sanded/ground past the gel coat on the whole boat to make sure my epoxy had a solid, clean surface to cling to. Most older gel coats are useless below the waterline as it does not restrict water migration as many think...it's just there for the showroom.

Greetings everyone!

I have been reading this thread and pretty much spent the last week on looking up osmosis and the remedies for it, since when I hauled out my boat there were about 20 or so bubbles on the bottom. I have just bought this boat so naturally I wanted to be sure.

In my case it seems that we had too many layers of bottompaint build-up and a mix of paint types that had formed the bubbles between paint layers. The blisters seem to have been "solvent blisters". The last layer was hard over soft...

There are pics on the blog but after I have scraped nearly the whole bottom and even sanded from where the bubbles were, everything is in perfect order. No gelcoat faults nothing alarming other than the idiotic layers of paint.

Up here We store our boats on the dry for nearly eight months of the year so the hulls have plenty of time to dry eventhough they are stored outside and its sometimes pretty cold here..

So, it's not always the worst case scenario although I already was convinced taht we had it.. Great forum, by the way..

Welcome tiku. Great looking boat!

Hi Tiku

A 1969 FRP vessel, one of the early ones for sure. Is it solid FRP up to the railings/gunwhales? I spent many fun filled days working and playing in Espoo. Great boating country and great people. How many cm of snow on ground?

Am I already hijacking the thread? (if so, sorry).

It is solid glass up to the deck which is made with 6 mm mahogany plywood that is covered with 15mm thick teak planking. The boat is from the first year when a FRP hull was an option. The FRP structure was made according to the standards issued by DNV (Det Norske Veritas).

Luckily there is no snow yet, but we are expecting some 20 cm to fall in the next few days.

Greetings,
Welcome Mr. tiku.

tiku said:

Am I already hijacking the thread? (if so, sorry).

It is solid glass up to the deck which is made with 6 mm mahogany plywood that is covered with 15mm thick teak planking. The boat is from the first year when a FRP hull was an option. The FRP structure was made according to the standards issued by DNV (Det Norske Veritas).

Luckily there is no snow yet, but we are expecting some 20 cm to fall in the next few days.

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Beautiful boat and you did the bottom job correctly. Thank you for cleaning up the scrappings instead of washing them down the drain as so many people do. I wish everyone would do the same.