Blisters - Spot repair or do whole bottom job

dtfeld

dtfeld

Water Contrails
GOLD Sponsor
Jun 5, 2016
5,551
Milton, GA
Boat Info
410 Sundancer
2001
12" Axiom and 9" Axiom+ MFD
Engines
Cat 3126 V-Drives
I short hauled the boat last week for a power wash and general inspection. Everything in pretty good shape but making a list of things to do in the off season and will be re hauling and blocking for a week or two. The one issue that was not expected was to find about 18 small osmotic blisters mostly about 1" in diameter. Pretty typical for this era Sea Ray and our location.

Can these wait 5-6 months until I'm ready to haul for several other items, or is this an emergency do it now deal?

Then the question becomes spot treatment, vs a complete bottom job. Spot treatment is $800-$900, a complete strip, barrier coat, and repaint is $4500. Current bottom paint is adequate for the lake I'm in, and would likely go several more years at which time I would do a complete bottom job.

I'm currently leaning towards spot treatment, knowing i may have a few more blisters when I do a complete bottom job.
 
DT, what year/model boat? SR (and a lot of others especially sailboats Jenneau, Benetau) had the blister problem in 86 87, but not heard of it since then.
What we heard back then it was a boom time for boat manufacturers, they were rushing through production without proper cure time. I had a few on an 87 268 covered warranty.
 
Pirate Lady said:
DT, what year/model boat? SR (and a lot of others especially sailboats Jenneau, Benetau) had the blister problem in 86 87, but not heard of it since then.
What we heard back then it was a boom time for boat manufacturers, they were rushing through production without proper cure time. I had a few on an 87 268 covered warranty.
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2001 - I have several neighbors with the 2000-2004 boats and it seems to be an issue for these years lately. For the most part they have been small (about 1" diamter) and not too numerous.. a dozen or 2 on a 38-41 ft boat. I think its a matter of how long the boats are in the water and temps around here. Our boats on the lake are usually not hauled but every couple years and the water does get pretty warm.
 
No rush. If you're sure it's just a few as you mentioned, I'd do the spot treatment. Check again in a year - if you're getting more, then do the whole thing.
 
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I think it depends on your approach to preventive maintenance. A spot treatment will give you some piece of mind. So you will pay the $900 and maybe get by until you need to do the entire bottom, in which case you will then pay the larger bill plus the $900 you are about to spend. My philosophy has always been to do the whole repair once and be done with it. Postponing the inevitable is usually more costly due to inflationary price increases in labor and materials, and this comes after you have paid for an incomplete repair. You might also have other issues that are hidden beneath layers of paint that will become more expensive to fix later. Just my two cents from a person who was compulsive about fixing every little thing that came up before they became costly headaches. I always felt my boat was in great shap and knew that it would be good to go on an extended cruise without letting me down. That is a good feeling.
 
Spot repair followed with a barrier coat, petit 4700, is what I did on a 1990 regal.So far so good.
 
The problem with a spot repair is can you leave the blisters open long enough to fully dry the fiberglass/resin in the blister to thoroughly dry. If you cannot, then a spot repair is a waste of time. 1" blisters are not a terminal event. What needs to happen is to haul out and block the boat up, then grind out the blisters (while you can see them; they will shrink and be difficult to find in a day or so). when the blisters are thoroughly dry, fill them with Polyester resin or epoxy with layers of fiberglass cloth. Then the repairs need to be faired and the entire bottom of the boat sanded and primed with an epoxy barrier coat and fresh bottom paint applied.
 
I’m not a fan of temporary fixes. You’re facing a full bottom job anyway. Skip the $900 spend and gitrdone right.
 
fwebster said:
The problem with a spot repair is can you leave the blisters open long enough to fully dry the fiberglass/resin in the blister to thoroughly dry. If you cannot, then a spot repair is a waste of time. 1" blisters are not a terminal event. What needs to happen is to haul out and block the boat up, then grind out the blisters (while you can see them; they will shrink and be difficult to find in a day or so). when the blisters are thoroughly dry, fill them with Polyester resin or epoxy with layers of fiberglass cloth. Then the repairs need to be faired and the entire bottom of the boat sanded and primed with an epoxy barrier coat and fresh bottom paint applied.
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The SR dealer would drape the whole boat with plastic sheet from water line to ground after grinding open the blisters then run a heater in the ‘tent’ for a week to dry it out. One of those gas torpedo heaters.
 
1" diameter blisters are not going to be that deep, so if you pick your weather window well, they should dry naturally in a few days. But the longer you wait, the deeper the blisters will be.
 
fwebster said:
The problem with a spot repair is can you leave the blisters open long enough to fully dry the fiberglass/resin in the blister to thoroughly dry. If you cannot, then a spot repair is a waste of time. 1" blisters are not a terminal event. What needs to happen is to haul out and block the boat up, then grind out the blisters (while you can see them; they will shrink and be difficult to find in a day or so). when the blisters are thoroughly dry, fill them with Polyester resin or epoxy with layers of fiberglass cloth. Then the repairs need to be faired and the entire bottom of the boat sanded and primed with an epoxy barrier coat and fresh bottom paint applied.
Click to expand...
fwebster said:
1" diameter blisters are not going to be that deep, so if you pick your weather window well, they should dry naturally in a few days. But the longer you wait, the deeper the blisters will be.
Click to expand...

Picking the weather window is my most immediate issue. The yards/manpower around here are full and wait times are several weeks to a couple months. I prefer sooner than later, so if I can get in the yard while its warm enough, I'll do it yet this year. If things don't work out weather or schedule wise, worst case I'm looking at March/April. I have several bottom related jobs to do including new cutless bearings, prop tune, anodes, some underwater light repairs etc.

As to the question of spot treatment vs full bottom job, I've been reading up on it and there are lot of useful opinions online from various sources. West Systems has a pretty extensive write up that takes a lot of factors into consideration. For minor isolated blisters, their take is spot treatment and monitoring for a couple of years may make sense ,and this was also an option in a piece done in Practical Boat Owner. Another point was that striping and barrier coating may or may not be the right thing to do (again a lot of factors to consider). One take away for me is this is blisters are slow to develop, so this isn't a "right now like today emergency", but needs to be addressed in the near term for sure.

Since I have what I consider a minor case of blisters, I think I'm more comfortable taking a measured approach to this for the time being, getting the spot treatment done and monitoring for a year or two. I had the most respected bottom guy on the lake with about 35 years experience look at it and he's the one to do the work, so I'm pretty confident it will be done right and with good materials (there's a reason he's booked up for several months).

If things turn south, a more aggressive approach will be warranted.

Links to a couple of things I found informative.

https://www.westsystem.com/wp-content/uploads/Gelcoat-Blisters-Diagnosis-Repair-and-Prevention.pdf

https://www.pbo.co.uk/expert-advice/diy-osmosis-repair-26475
 
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I agree with Frank…

Here is my opinion, if you have a few then the bottom is susceptible to blisters and if there is a barrier coat it is failing. You need to fix the source of the issue which is the lack of or failed barrier coat. Then fix the symptoms which are the blisters. If you do a temporary fix you will have another temporary fix in the future. Fix it once and be done but it’s not an emergency today.
 
Getting boat hauled and tackling the blisters myself for a lack of anybody able to get to it (lack of manpower)?. Following the BoatUS guide and using West Systems 105/205/406. I've got the time and a great weather window (70's all week), and I've got all the supplies ready to dig into it. Fiberglass is not my favorite, but looks like schedules aren't going to match up. At least I'll know it done to my satisfaction...

--> https://www.boatus.com/expert-advice/expert-advice-archive/2013/june/gelcoat-blister-repair

Not knowing what paint is on it, I bought a quart of Petit Hyrocoat as it is supposed to be able to be applied over any existing paint.

Hopefully this gets me a year or two down the road and re-evauate the whole bottom paint issue.
 
Once you start doing it, you'lll find it goes quicker than you think. A LIGHT touch using a grinder with a fine grit flapper wheel will make easy work of exposing the blister and sanding back to where you see the gel to glass is solid. It also pretty much ensures you have a nice angle to the perimeter of the repair. Acetone is nice for a quick clean-up before using the epoxy. Don't go too crazy trying to make the repair perfectly fair/flush with the surrounding gelcoat. It's going to be hidden by the AF. Honestly, if you don't need to go into the glass much, you're probably fine with just a couple quick coats of the epoxy by itself. A little thickener might be all that's needed - and that's also easy to fair with an old credit card or plastic spreader. If for some reason you have a deeper hole, then add some glass. Keep in mind that not all glass (mat) is compatible with epoxy (as opposed to polyester) so it's best to stick with cloth. In the end, there's really no one best method so following any of the good advice above will work. Tip... get all of your glass cut (if needed) BEFORE you start working and lay it out/stage it. Also, don't mix up too much of the epoxy at a time as it will kick before you use it. You can, however, mix it up and then pour it into a shallow pan to extend the working time quite a bit.
 
Finally found my glass guy, been out with the 'Rona, but said he's up for the spot repairs. This one I'm glad to leave to the professionals.
 
My glass guy Wes ground them out. Will let them dry a couple days, said several layer of glass, some fairing compound and finally a little bottom paint.

I think 22 of them, ranging in size from about 1-3". Beats the Carver next to me with a case of Boat Pox...1200 little blisters.

Glad I'm getting these taken care of by a guy that knows what he's doing!

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Hopefully he is applying barrier coat before the bottom paint.
 
Yup, sometimes it's nice to put bread on someone else's table! :)

NHD, the epoxy that the repair guy will be using is fully waterproof and doesn't require an "epoxy" barrier coat. The barrier coat is used over the entire gelcoat when a full bottom job is done. There's no need for it when doing a spot repair since the repair is fully waterproof by itself. Chances are very good that David won't have anymore issues. But if he does, then the next step is to remove all the bottom paint.
 
However, if he has that many blisters now, unless he sands/sand or soda blasts the bottom completely, and barrier coats the entire bottom he likely will have more blisters appear in areas other than the spots where the current blisters are.

I went through this when my bpoat was about 15 years old. We ground out the blisters and let them dry then we soda blasted the hull to remove all the bottom paint. Then put 3 coats of InterProtect 2000E on the entire bottom and put fresh bottom paint on the hull. That pretty much solved our blister problem other than an occasional blister every other year of so.

Freshwater boaters cannot get into this but a good part of avoiding blisters is inspecting the bottom regularly and fixing little problems before they became big problems. Even trhough we get 3-4 years out of a good bottom job on the Gulf Coast, I hauled out boat out of the water and inspected the bottom every year.
 
Blisters are a funny thing. I've had boats (salt water) where they get zero blisters and one, in particular, that looks like it has a raging case of chicken pox. Had that boat in the family since 1982 - it does come out of the water for about 5 months each Winter and they shrink down, though. Then they swell up again - but they're all just small ones and that hull is still solid as ever. I used to worry about it - but time has shown me that, in this case, it's all good.

And still others that have had a few, maybe a dozen or so, fixed 'em and then never got any more.

For something that seems so simple, they sure can be strange little buggah's!
 
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