Blisters - Advice Sought

[Target9000]

I know the subject has been discussed to death. I'm asking for someone to help me determine specifics in my situation which is this:

The yard called me and told me they'd have to re-evaluate our price on painting due to blisters. I was told the blisters don't penetrate the gel coat but ARE under a previous barrier coating.

I went and looked at the boat today. There are hundreds of spots where the blisters popped and paint is chipped away. Many more still not popped. They are fairly large. I prodded at what was under the paint trying to find soft spots but couldn't find any. Appears the damage is shallow.

The outer most part of the hull has blue paint that rubs off to touch. I'm assuming soft ablative paint. Under that is a layer of reddish paint that seems hard. I'm guessing this is a hard ablative paint that was painted over. Underneath that, it seems that in places there is some yellowish material but only in certain places. I'm guessing this is a layer of epoxy? Barrier coat possibly? In other places its just white, either smooth or not. I'm guessing this is the gelcoat. But I've never seen this stuff first hand. Looking for someone to help me understand what is going on here and not have the wool pulled over my eyes by the yard.

Please check out my photos of the situation.






Also here.
Engine Haul out day

[osirissail]

It appears from your photos that what you have is the failure of the barrier coat to adhere to the polyester resin hull. This is not uncommon when a "quickie" job is done barrier coating a hull. Getting epoxy to adhere to polyester resin is involved in that all grease, water, dirt, and other foreign contaminants can prevent the epoxy from getting a grip on the gelcoat/hull.
- - Barrier coats that are improperly done have been known to fall off the hull in quite large sheets taking the anti-fouling paint with them.
- - So the boatyard is looking at removing all of the old bottom paint and the old barrier coat. Then they would, most likely, want to put a proper barrier coat on the hull and then the bottom paint.
- - Depending upon the regulations in effect in the particular boatyard you are in - you can get the old paint and barrier coating - "blasted" off - and then properly prepare the hull's gelcoat/laminate to accept a new barrier coating. Then put the bottom paint on yourself. Or have the boatyard do the whole thing.

[Target9000]

So is removing the old barrier coat as severe as taking off the gelcoat? I've read a lot about blister repair and it appears when you take this stuff off there are hundreds of hours in fairing the hull and whatnot. I'm hoping this isn't as severe? Or is is six one way and half a dozen the other?

[bstreep]

Hmmm. This one is troubling.

Not sure the pix are showing the whole story. I see a couple of problems here - maybe not TOO bad.

1) You have an ablative paint over a hard bottom paint. That usually doesn't work out well. The good news is that the ablative paint can be removed with power washing.

2) It looks like you have a failure (blistering) of the hard paint that's under the ablative paint. Again, that's not the end of the world - it's blisters.

So, what I would do is this: I'd powerwash the ablative paint off of the bottom. Completely. This will give you a good look at the hard paint bottom. If you have less than a couple of hundred blisters from there, grind them out, fill them, and put a HARD paint over them. We're in Texas, and use Interlux Ultra with Biolux - it's lasted us 3 years, and we are putting a new bottom on next week (along with about 50 blister repairs).

If you have more than a few hundred blisters, it's time to look at that barrier coat. It may have to be removed.

Upon the advice of our surveyor when we bought the boat (the consensus is that he's the best on the Gulf Coast - Mike Firestone), we have taken the above approach to blisters. I honestly think that the hard paint really helps this process.

[sabray]

I agree Osiris. Possible that prior application was soda blasting or sandrhen barrier. Maybe didn't get deep enough didn't bond etc... Hard to say for sure but the laminate looks pretty good in the picture. Given I'm looking at a picture on a phone. Do it right this time and be dine with it.

[delmarrey]

I'm with the rest here. I don't see blisters, but de-lamination/flaking.

The cheap route would be to sand and clean real good, and just paint over it all. The bottom would be a little rough but it is a full keeler so not much speed loss.

A more preferred route would be to blast it all clean. Add another/new barrier coat. Sand and paint.

The white could be paint or gelcoat. If it's hard like glass then its gelcoat. If it's paint, it could be just an undercoat.

The red could be oxidized old bottom paint.

[westsail42]

Ditto with the others. Looks to be a bad barrier coat,

I would sand/strip the bottom paint and barrier coat down to the gelcoat. As it appears all blisters are shallow, I am not sure a barrier coat is necessary. Westsails have a pretty good record of little to no blisters.

If the hull laminate is dry (according to moisture meter), then that might be another reason to fore go the barrier coat.

If you do go with the barrier coat, I recommend two coats of straight West Systems on a VERY CLEAN bottom (wiped with acetone), 80 grit sand, then two coats of Interlux 2000E, then 80 grit, then bottom paint.

VERY IMPORTANT to barrier coat with the hull as dry as possible according to the moisture meter.

YMMV of coure.

[Target9000]

Originally Posted by delmarrey

I'm with the rest here. I don't see blisters, but de-lamination/flaking.

The cheap route would be to sand and clean real good, and just paint over it all. The bottom would be a little rough but it is a full keeler so not much speed loss.

Do you see any long term detrimental effects from taking this cheaper route? The problem appears to be cosmetic and if we're only talking about eeking out a little more speed by paying for the whole enchilada, we'll pass. At least for now. The budget for this year is already stretched thin by our plans to repower.

[minaret]

Originally Posted by westsail42

Ditto with the others. Looks to be a bad barrier coat,

I would sand/strip the bottom paint and barrier coat down to the gelcoat. As it appears all blisters are shallow, I am not sure a barrier coat is necessary. Westsails have a pretty good record of little to no blisters.

If the hull laminate is dry (according to moisture meter), then that might be another reason to fore go the barrier coat.

If you do go with the barrier coat, I recommend two coats of straight West Systems on a VERY CLEAN bottom (wiped with acetone), 80 grit sand, then two coats of Interlux 2000E, then 80 grit, then bottom paint.

VERY IMPORTANT to barrier coat with the hull as dry as possible according to the moisture meter.

YMMV of coure.

Interlux Interprotect 2000e calls for a minimum Dry Film Thickness of 10 mils. This requires 5-6 coats to achieve with a candy striper roller cover, the recommended applicator. 2 coats is not enough to provide a barrier and you are essentially relying on the WEST at that point. Which is OK as WEST makes a decent barrier coat by itself, but you could just leave the 2000 off if you're doing it that way.

http://www.yachtpaint.com/MPYACMData...Y+20100614.pdf

Looks like it's not laminate blisters to me either, just needs a bottom paint removal and some dry time, followed by fresh barrier coat. 6 coats of it. Moisture meter should read 10% or less. Manuals all say 5% but you'll rarely see that in the real world. I've seen hulls take 6 months to dry out back in the old days before we got our Hotvac machine. The Hotvac uses the principle of water evaporation at lower temperatures under vacuum to remove the moisture from your hull. Essentially under a vacuum water boils around 180 deg. and so can be evaporated and pulled from your hull, using a series of heated vacuum pads. Anyone looking at a long dryout should try to find a yard equipped with one, I've dried hulls reading in the 50-60 range to less than 10 in a week. I've dried saturated cores with it too...

[minaret]

Originally Posted by Target9000

Do you see any long term detrimental effects from taking this cheaper route? The problem appears to be cosmetic and if we're only talking about eeking out a little more speed by paying for the whole enchilada, we'll pass. At least for now. The budget for this year is already stretched thin by our plans to repower.

If you're relatively hale and hearty do the job yourself. All you have to do is build a tent around the bottom, break out the 7" softpad sander and 36 grit, and sand all that old crap off your bottom. Once the tent is set up I could do your boat by myself in one day. One exhausting day. Then all you have to do is clean it up, stack on 6 coats of 2000e, chemical bonding each one ( no sanding), and then you can chemical bond the bottom paint as well. It actually sticks much better that way than if you sand the 2000. The yard will charge you a ton of money to do the job, but if you do it yourself you'll find it's surprisingly simple. Just hard work.

[Target9000]

Originally Posted by minaret

If you're relatively hale and hearty do the job yourself. All you have to do is build a tent around the bottom, break out the 7" softpad sander and 36 grit, and sand all that old crap off your bottom. Once the tent is set up I could do your boat by myself in one day. One exhausting day. Then all you have to do is clean it up, stack on 6 coats of 2000e, chemical bonding each one ( no sanding), and then you can chemical bond the bottom paint as well. It actually sticks much better that way than if you sand the 2000. The yard will charge you a ton of money to do the job, but if you do it yourself you'll find it's surprisingly simple. Just hard work.

You inspire me minaret. But my God, its going to take a lot of beer.

I understand that chemical bonding is putting on the "next" coat while the first coat hasn't fully set right? You say you can bond the bottom paint as well? Which bottom paints make a good candidate for that process?

Also do you build the 2000, let it dry, sand it and then go to paint, or do you put the first coat of paint on the last layer of 2000 before it is dried?

[minaret]

Originally Posted by Target9000

You inspire me minaret. But my God, its going to take a lot of beer.

I understand that chemical bonding is putting on the "next" coat while the first coat hasn't fully set right? You say you can bond the bottom paint as well? Which bottom paints make a good candidate for that process?

Also do you build the 2000, let it dry, sand it and then go to paint, or do you put the first coat of paint on the last layer of 2000 before it is dried?

You got it on the chemical bond. Dry time for 2000 depends on temp, but in your neck of the woods you should be able to do 2 coats a day no problem. One coat first thing in the morning, second coat in the evening. The window for chemical bonding 2000 used to be 24 hrs, but I believe the newer formula gives you something ridiculous like two weeks.
The place most people screw up on this job is the sanding. Dont let anyone talk you into using anything but 36 grit. Anything finer is a waste of time, as is a vac sander, or DA arraingement of any kind. Makita buffer/sander with a 7" soft pad and 36 grit imperial stikit disks. You'll need a Tyvek suit, a fullface respirator, a roll of 12'x 100' Visqueen to make the tent, and a good vacuum. Bag off the whole bottom with the plastic, taping to the hull several feet above the waterline. Put in a bunch of scrap lumber pokes to hold the plastic out and wait for a day thats not too hot or windy. Then blast it out and clean up well. Weekends when noone is around are good. Spectators are bad, some degree of dust plume is inevitable. Once youve got a nice clean 36 grit profile on your botoom, check it with a meter, dry it out, and start in with the 2000. People will tell you to sand to a finer grit before coating but ignore them. By the time youve stacked on 6 coats of 2000 you wont be able to see the 36 grit scratches at all, unless you hacked it up real bad with the soft pad. Then chemical bond the bottom paint, 2 coats at least. If you use a candy striper roller cover throughout and lay it off nice when rolling you'll have a nice even texture to your bottom that looks very proffesional. I like Trinidad SR for bottom paint. If you dont want to pay for SR (Slime Resistant) use the regular Trinidad, it likes epoxy. If you get all your coats of 2000 on and dont like the way it looks you can sand it with a finer grit before painting. But you shouldn't have to, it's a waste of expensive 2000.
Hope that helps...oh and check the link in my previous post for info on 2000...

[delmarrey]

Originally Posted by Target9000

Do you see any long term detrimental effects from taking this cheaper route? The problem appears to be cosmetic and if we're only talking about eeking out a little more speed by paying for the whole enchilada, we'll pass. At least for now. The budget for this year is already stretched thin by our plans to repower.

Without being there and putting my hands on it, I wouldn't commit myself just off of what I see on the net. But I would confide in some locals there that have the experience to know what they're looking at, that are not seeing $$$.

Find someone in the yard working on their own boat bottom. An older guy, that looks like he knows what he's doing.

Otherwise, scrape or sand a little more and post some more pictures until we can see the real status.

BTW was the bottom pressure washed?

[Target9000]

Originally Posted by delmarrey

Without being there and putting my hands on it, I wouldn't commit myself just off of what I see on the net. But I would confide in some locals there that have the experience to know what they're looking at, that are not seeing $$$.

Find someone in the yard working on their own boat bottom. An older guy, that looks like he knows what he's doing.

Otherwise, scrape or sand a little more and post some more pictures until we can see the real status.

BTW was the bottom pressure washed?

Yes it was when they hauled it out. Unfortunately I wasn't notified when they were pulling it out so I wasn't there.

I'd try to find someone but the yard I'm in is... Well I don't know that I'd trust any of the folks I've seen around here to tell me whats what. That is why I've turned to you guys.

I'll try to sand down some spots in the coming weeks and post photos of whats going on.

[doug86]

Lets see.... a bunch of paint failing on top of fiberglass. Adhesion problems, incompatible products, incorrect application techniques and preparation failures has all led to where you are right not.

Just a guess, but perhaps the trouble all began with do-it-yourselfer attempting to take the cheap alternative and taking advice from strangers of unproven skill levels, of just asking the old guys around a yard... as if age had anything to do with product knowledge.

Be very careful how you proceed from here, else you end up in the same circumstance at your next haulout. I'm not suggesting that you can't do this job yourself, but make sure you understand the various paint/epoxy products and application processes before you begin. Talk to a rep at the paint company.

Grinding the old stuff off with 36 grit may not be the answer, as you will be grinding all those incompatible products (old paints, epoxies, even wax god forbid) deep into the pours of the fiberglass or gelcoat. A soda blasting or even a wet sand blasting actually removes the old paints and crap and is a better alternative to using heavy grit disk sanding.

A successful paint job is all about the prep.