Blister Question

I know blisters have been discussed at length on TF, but wanted to get a gut check. We found a boat we really like and have viewed it 2x. Had a chance to review some prior survey results (from about 2 years ago). Noted a few entries related to the haul-out that have me concerned.

Surveyor noted "many paint blisters" and "several osmotic blisters less than 1/2" in size" (no pics unfortunately). Final note was that the bottom paint should be heavily sanded next renewal.

I'm following up with the seller and also going to see if I can talk to the surveyor that did the survey to get some more color.

So here's the question - assuming this has not been addressed by the Seller and I don't get any more color on the issue, would you proceed forward with an offer and have it inspected and then make a decision based on its current condition, or just keep looking? The boat looks to be in good condition otherwise, but blisters and the "heavy sanding" don't sound good. My more conservative side tells me I may be better off to just keep looking, but would appreciate thoughts on the matter.

Are they both above and below the waterline?

If it is an older boat with solid glass below the water line and no other serious issues this would be of little concern to me. If a 5 year old boat then I would probably not consider it. I have not nor would not owned a boat with cored hull below the waterline but that is just my personal preference.

I haven't seen any above the waterline. Presume all below waterline.

Ready - when you say "solid glass below the waterline" what exactly do you mean? Also, why would the hull be cored? To determine how bad deep the blistering is? Sorry - i'm a bit of a newbie when it comes to these bigger boats (40' +)

If I bought the boat I would have it soda blasted and then do repairs to the blisters as needed. No way to tell by just sanding how many there are, some can be small and if the boat has been out of the water they tend to shrink. Your decision now is do you want to roll the dice on a complete, maybe, bottom blister job? At a very minimum you need to negotiate a large price reduction to do the repairs. Good luck.

First, I've never heard of a boat sinking due to osmosis.

Second, if the blisters are confined to below the waterline and quite extensive, you should have the hull blasted to remove all the old antifoul. Then, given the age of the boat, I'd have the gel coat peeled, damaged areas ground out and remade (with bi-axial cloth, if necessary), re-gelled, and epoxied.

When I had Play d'eau's hull blasted and epoxied, no epoxy manufacturer would warrant more their products for more than 5 years protection. In other words, epoxy isn't a boat life-time guarantee, only a product life-time guarantee.

Once done, you'll have a good hull. If you only treat blister by blister, they'll keep coming...

greatpapabear said:

First, I've never heard of a boat sinking due to osmosis.

Second, if the blisters are confined to below the waterline and quite extensive, you should have the hull blasted to remove all the old antifoul. Then, given the age of the boat, I'd have the gel coat peeled, damaged areas ground out and remade (with bi-axial cloth, if necessary), re-gelled, and epoxied.

When I had Play d'eau's hull blasted and epoxied, no epoxy manufacturer would warrant more their products for more than 5 years protection. In other words, epoxy isn't a boat life-time guarantee, only a product life-time guarantee.

Once done, you'll have a good hull. If you only treat blister by blister, they'll keep coming...

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What the full bottom job like that run (per LF)?

Different companies will charge different amounts if they use different methods. Note that the boat will need tenting which would be an addition.

For Play d'eau, the underwater quote in 2014 was:

To carry out a full epoxy treatment with West System Epoxy.

This epoxy treatment includes peeling, blasting, steam cleaning and tenting, ready for drying out with infrareds and dehumidifiers.

Applying saturation coat filling and fairing, applying one 450 bi-axial cloth and then six coats of solvent-less epoxy, tie coat and two coats of antifouling to finish.

The drying time required would depend upon the level of moisture found on initial inspection and the conditions under which the vessel is allowed to dry.

Total: £19,800 (pounds sterling).


Play d'eau's waterline is about 50', making it around £400/ft.

Willard Marine was one of the builders with blister problems. As moderator of the Willard Boat Owners Group for the past 21 years, I've had more than my share of blister conversations.

My boat had a pretty good crop of blisters. Hundreds of them. Most were quarter to silver dollar sized. My attitude was it's a displacement hull, it's about an inch thick, who cares? Only downside was whenever I'd haul, some brainiac of a boat owner would walk up and and observe "looks like you have blisters!" Thank you Captain Obvious.

Seriously, I received a fair survey credit for the blisters when I bought the boat, and I always figured I'd give it to the next buyer down the line. I saw no reason to repair them. In my opinion, the performance drag at displacement speed can't be much, if any. Why bother?

But not all buyers are as accepting of blisters. My first Big Boat was a 42' Uniflite, another brand known for blisters. Mine was a model year just prior to the big problems so didn't have many, but did have a handful below the waterline - maybe a dozen or so. The first prospective buyer flipped out when the boat was hauled - and I mean he totally went berserk - screaming that it should have been disclosed the boat had blisters and wanting to sue me and both brokers for the haul and survey (I remember his broker clearly saying "John, if you want a boat with no blisters, you should be looking at wood boats"). In all fairness, the guy was a jerk from the get-go. The boat was one of those older models with twin beds in the stateroom and he really wanted an island queen, and thus asked for a $25k survey credit, ostensibly to repair some minor teak damage (stupid me - I had accidentally drilled though a plywood panel and put a pinhole in the fiberglass exhaust tube behind it - repair was simply removing the teak ply panel, repairing the hole, and replacing the panel with an identical one - took about 6 hours of work including store runs).

So my advice is several fold. First, does it even need to be repaired? You don't say the age, size, type, and value of the boat, but there are several scenarios where I wouldn't bother. Or, at the very least, it wouldn't be high on my list. Second, it will effect resale, so you can't ignore them completely - even if you do nothing, they will have an effect. Finally, a repair is no guarantee they won't reappear. Chances are they won't be prolific, but chances are good that you will see a few from time to time.

Personally, my biggest concern as a buyer is whether the seller will be reasonable about a credit. Just like I described a buyer who was a jerk, there's nothing that says a seller can't stand tall and say the boat is as-is/where-is. As a very rough rule, I don't expect a credit for 100% of the cost on an older asset - 50% seems about fair. You can get a quote at the yard while she's hauled for survey. Most of the quotes I've heard in the past couple years are in the $400-$500 per foot range for a full peel, glass, barrier, and paint job.

Long story to say I wouldn't hesitate to buy an otherwise nice boat so long as the blister defect was adequately compensated. My first reaction would be to not fix them, or perhaps repair them opportunistically over the course of a few hauls

BTW - while my boat was in the yard in Mexico for refit work (over a year), the guys ground-out and glass/filled almost all my blisters. Frankly, from pictures, the work doesn't look pristine so my heirs will have to still deal with a survey credit of some sort, but much better than it was. Not that I care too much.

Good luck.

Peter

Blisters are not the problem.....hydrolysis is and blisters may or may not be present.

Heavy paint is not an issue, and paint blisters just signal that a painting restart is probably a good idea.

Back to hydrolysis....I have never heard of a boat sinking from blisters, yet heard of some becoming uninsurable or the USCG declaring them structurally unseaworthy. There may have been boats with these serious issues that have made the bottom or junk yard and we just never heard that blisters/hydrolysis were the problem.

My bottom was bad enough that without repair, if I were a surveyor I would have never passed it or an insurer, I wouldn't have insured it. The surveyor I had noted blisters....but no mention of hydrolysis.

My "new" attitude towards boat bottoms is BEWARE.....mostly towards bottoms where people say "blisters don't sink boats" because it can lead to insufficient bottom jobs. So unless I read a thorough report on what was done to the bottom and what was discovered after a peel/grinding.....I would bypass.

There seems to be a small group of marinas that do a lot of "blisters repair", surveyors that have studied the subject or have the experience, and other marine professionals that fit this group that truly understand the problem. Granted most boats with a few blisters are not ticking time bombs, but many more boats are suffering from hydrolysis and its not even known which ones or how severe.

And to be fair...in the areas that I had severe, deep hydrolysis....it still passed the tap rap test.

Like you, we found a boat we really liked except for over 100 blisters on the port side hull, seller offered a $25/blister credit, we walked. It depends on your tolerance for them and the possibility of returning blisters down the line.

Cored Hull

JohnO said:

I haven't seen any above the waterline. Presume all below waterline.

Ready - when you say "solid glass below the waterline" what exactly do you mean? Also, why would the hull be cored? To determine how bad deep the blistering is? Sorry - i'm a bit of a newbie when it comes to these bigger boats (40' +)

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JohnO: most boat hulls are built using solid fiberglass at least below the waterline. But a smaller portion sandwich a core of balsa or foam inside the glass which is much lighter than solid glass. Foam is a lot more expensive but will not rot if water penetrates. Not so with balsa wood.
Above the waterline it is much more common and acceptable to use a core but even there you need to be careful. Drilling holes or screws can lead to core damage.

I would suggest you share more details about the make, model and age to get more advice from the forum. Also a good surveyor can be very helpful.

JohnO said:

Surveyor noted "many paint blisters" and "several osmotic blisters less than 1/2" in size" (no pics unfortunately). Final note was that the bottom paint should be heavily sanded next renewal.

I'm following up with the seller and also going to see if I can talk to the surveyor that did the survey to get some more color.

.

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Paint blisters simply mean that there are spots of bottom paint that didn’t properly attach to the hull. Are they the size of a dime? Not much of an issue. Are they 6”? Boat will need the bottom paint sanded off and better bottom prep before repainting. Small issue for the right boat.

The word several means 2 to 4 blisters. Size 1/2”. If this is a 20+ year old boat, a total non issue. If this is a 10 year old boat, still a non issue in my book. Less than 5 years, problems going to get worse but how much I don’t know. (I am assuming these blisters are below the waterline). Boats that blister above the water line make me nervous for cosmetic resale reasons.

JO
What year, brand and model of vessel are considering? Is your budget sufficient to consider a vessel that is "largely" blister free according to a quality survey?

Also, those boat owners with blisters will say no problem, they may or may not be right.

Never heard of paint blisters. Flaking due to poor preparation or electrical current caused removal yes, usually called halos around through hulls etc.

Gelcoat osmosis blisters if small and not many can easily be ground out and filled.

READY said:

I would suggest you share more details about the make, model and age to get more advice from the forum. Also a good surveyor can be very helpful.

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Sorry, I meant to give boat details in initial post, but apparently forgot ... Its a 1980 43' Ocean Alexander Tri-Cabin.

From the feedback so far, and given that the boat otherwise looks like she's been really well maintained, I'm kind of inclined to make an offer, and get a haul-out/survey done and see what we're really dealing with ... still plan to see if I can get more color from Seller / prior surveyor.

Get a quote from your local boatyard for the following:
1) Remove all bottom paint with belt sander
2) Remove all blisters 1/2 or larger with DOA sander
a) repair fiberglass and fair
3) Apply 2 coats of epoxy (barrier coat, optional)
4) Apply 2 coats bottom paint

If you are at a small yard you'll probably be in the 5K range min., 10K if you decide on barrier coat. Split the cost with the seller. It's a common DYI job but not exactly a pleasant job.

Barrier coats are usually specified in mil thickness buildup instead of XX coats.

Removing some but not all blisters present is a new one on me and I did 8 solid months of blister/hydrolysis research.

SoWhat said:

Get a quote from your local boatyard for the following:
1) Remove all bottom paint with belt sander
2) Remove all blisters 1/2 or larger with DOA sander
a) repair fiberglass and fair
3) Apply 2 coats of epoxy (barrier coat, optional)
4) Apply 2 coats bottom paint

If you are at a small yard you'll probably be in the 5K range min., 10K if you decide on barrier coat. Split the cost with the seller. It's a common DYI job but not exactly a pleasant job.

Click to expand...

I would never try to use a belt sander to remove bottom paint. Bottom paint is a haz material and a belt sander will throw it all over even with a shop vac hooked up to it. Besides it will be very difficult to sand the bottom evenly working upside down. Much better to have the bottom professionally soda blasted. It isn’t that expensive in the scheme of things and your health is more important. Then you can do the blister repairs yourself. It isn’t that difficult except it also is upside down. After all the repairs you need to put on an epoxy barrier coat, that is a must not optional. Do not just do 2 coats. Do what the manufacturer specifies. The last boat I did they said to use 5 gallons of epoxy so I did 6 gallons. You just keep doing coats until you have used all the specified amount of paint. In my case it was 6 coats. Then do the bottom paint. You have to recoat at the proper time so that you don’t have to sand between coats, usually thumb print time. When you can leave a thumbprint in the paint but the paint doesn’t transfer to your thumb. It is definitely a bugger of a job to do it right but then you shouldn’t have any more blister problems. Good luck and take some Advil.

Ha - I already need Advil and some whiskey to wash it down. Comodave - you beat me to my question about soda vs. belt sanding. Given my inexperience, I'd probably hire this out first time around and ask the seller for 1/2 as a credit as SoWhat suggests (and SoWhat, great outline of what to do - thx). But to psneeld's point, I'd just fix whatever blisters were there regardless of size.

Follow up question - what's considered the best epoxy barrier?

... And SoWhat - just curious ... you a Miles Davis or Bill Evans fan?

Soda blasting costs will vary by location. I paid $35 per foot about 6 years ago here. I would use the Interlux system. Use all their products, don’t mix and match. Follow their directions to the letter. No shortcuts, they have much more experience than any of us. So when someone says that you don’t need to do a step or do it differently, don’t listen. Interlux has a great support unit and has worked diligently with me in the past. When I had that boat soda blasted I had about an hour ot two of hand sanding to touch it up and get it ready for the epoxy barrier coat, or in your case the blister repair work.

OA do not have a blister reputation. 1980 boat with several 1/2” blisters is a total non issue to me and I wouldn’t even touch them. Paint blisters is probably a non issue but a boat that age might have so many coats of bottom paint that it’s starting to have a cottage cheese appearance. If this is the case then let a yard strip it for you. They may choose to grind it or chemically remove but let them deal with all the haz-mat issues.

If you really like the boat otherwise, make an offer subject to survey/unfettered insurability, approaching survey willing to walk if you don`t like what is revealed, willing to burn the survey and associated expenses. I did this with my present boat, regarding the purchase as a 50/50 prospect based on the knowledge it had small widespread blisters, and it was interstate as well. None of the blisters were found to be osmosis.
While it`s better to have both the mechanical and general surveyors present together, maybe get the general survey first and hope he does a good job of the things you can only check out of the water, like running gear, rudders, etc.
Miles Davis and Bill Evans have different styles but liking one doesn`t exclude liking the other.

I had my 47 done for 200/ft in Louisiana. Haul wash sand blast patch, and 3 coats paint.

You should not concern your self about the paint blisters as just heavy sanding or soda blasting then fresh paint would do the trick. the other blisters that are less 1/2 inches are fixable and is not a big deal either. If you really like the boat then concentrate on structural issues or any engine major work.
Good luck

At the risk of getting into a spirited debate...
If there are random 15-30 relatively small blisters I would just treat and NOT do a full epoxy job. I did just this on my recently purchase 1976 Hatteras. As pointed out the epoxy vendor is not going to guarantee nor claim this is a cure all. $15-$20k for an epoxy job will pay for periodic blister repairs each time you haul for bottom paint probably for longer than you will own the boat. Getting a seller to cover half or more of an epoxy job for a limited qty of blisters on a 40 year old boat is going to be challenging.

Ready,



How many blisters is "Many".

I had Star done 3 years ago, 83 of them ranging from 1/2 to 4"x6". Some of the bigger ones were leaking through the hull. The bill was an unexpected $3800.

My suggestion is to find out how many blisters there are and how big they are. Repairs can be spendy.

Thanks again guys - this is truly helpful. I have to say having been a part of many forums (not boating specific), this community is one of the best ... everyone has been so knowledgeable willing to lend a hand. Can't thank everyone enough ... and Bruce, I agree. Was curious about SoWhat's name and whether or not it had anything to do with the Miles track of the same name on "Kind of Blue" ... one of my faves

READY said:

At the risk of getting into a spirited debate...
If there are random 15-30 relatively small blisters I would just treat and NOT do a full epoxy job. I did just this on my recently purchase 1976 Hatteras. As pointed out the epoxy vendor is not going to guarantee nor claim this is a cure all. $15-$20k for an epoxy job will pay for periodic blister repairs each time you haul for bottom paint probably for longer than you will own the boat. Getting a seller to cover half or more of an epoxy job for a limited qty of blisters on a 40 year old boat is going to be challenging.

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[emoji106]
Agree
Current boat had about a dozen quarter size blisters when hauled for survey. Negotiated a reasonable allowance from seller (don't remember exactly but <$1000) scraped & left open during winter storage, ground out, rinsed, dried, proxy filled, spot barrier coat in areas of blisters only. No additional issues over 8 yrs of ownership.

Thanks again to everyone for giving me some great perspective on the issue. Pleased to say we've got a deal on the boat. Moving to survey and hopefully will go well. Will keep everyone posted! Hoping I can pay it forward soon, but much to learn about this exciting new hobby.

- John