Blister Advice

[Dixie Life]

We just pulled our boat out for the first time. Told the yard to clean bottom & apply a coat of A/F paint. Yard called next day, said I needed to look at bottom. It had blisters about the size of a pencil eraser all over it. The guy said it looks like years of bottom jobs were applied on top of the previous coats. Also, the A/F paint was real caulky and flaking off. So, they sandblasted it off to the gelcoat taking the blister tops with it. Now, the yard guy said the boat will have to sit an dry out before they add 3 barrier coats and 1 awlfair coat. He will take moisture readings day 1, day 30, day 60. OK, but here is where I get confused. The boat is out in the open yard, it rains here once or twice a week. I was told that wouldn't hinder the drying time. Does all this sound right? Please see pics & advise. Thanks

 

[Andy G]

No pics, try again

 

[Alemao]

???? Pics ??

Sergio "Alemao" Sztancsa, Sent from my iPhone using Trawler

 

[Rambler]

If you trust your yard guys, you have to keep trusting them to be giving you the right advice, and doing you right on the repair work.

 

[Tom.B]

Here is the advice and arguments on the exact blister work we are in the middle of right now. PM me if you have any questions.

http://www.trawlerforum.com/forums/s32/thoughts-blisters-7593.html

 

[Nomad Willy]

dhiggins,

I've got my boat out and intend soon to make a little skirt out of wide tape. I'll put something on one edge of the side of the tape (sticky side) and then put it on the hull about where the WL is w the attachment on the inside of the lower part of the tape so the lower part of the tape not only dosn't stick to the hull but turns out a little kinda like up side down flare. The idea of all this is to provide a means for the water running down the hull side (when it rains) to break away from the hull and fall straight down. This way it won't follow the curve of the hull and run all over the blisters. This is a lot of words to convey something quite simple and I don't know if anybody has ever done this but it would seem to me that it would keep the water off the blisters and couldn't help but assist getting the blisters dry. Is this all understandable?

 

[BruceK]

Interested to see pix, hope you mean the rubber on the end of a pencil. The opinions on the thread GonzoF1 raised are anything but unanimous.
I have seen a hull left to dry with plastic sheeting on a frame around it, I agree with trusting the yard, you need to think about what you are told, but they`ve seen the blisters and are well placed to advise what and how to do it. Some will happily second guess your yard.
July/August 2011 we went down the path of the yard grinding out each of many large blisters to dry, then filling with fiberglass mat and epoxy; it just came up, looking great. Your blisters sound smaller, more generalized, less deep, treatment may be different. Is there a blister history you know of/can discover.
Eric`s idea of a diversion drain should help if you can get it to work but won`t stop wind driven rain/spray. Logic suggests if you are trying to get moisture out from inside it will be good if the outside is not wet.

 

[VixenII]

Also, keep in mind that blisters are caused by excess MEK or similar stuff. The yard may be saying that your boat needs 2-3 months of drying IOT to allow for full drainage/evaporation of these chemicals. When we began our project boat we took the hull to bare fiberglass. We pressure washed the hull several times to help clean out the blisters. Sixty days sounds about right for the whole process. We also faired the deeper items before applying the barrier coats. After four years - there is no re-occurence of the problem. Worth the effort.

 

[awpptdt]

Yes, it will dry. The rain just runs off and does not soak in. It will dry much faster if it is protected from the weather and heat or dehumidifier is applied. Place a skirt around the hull to the ground and under the boat, a dehumidifier will do the job.

 

[psneeld]

it will not dry with gel coat still there without heat pads.
not unless it's localized, light moisture...or you wait ,any months to years depending on many factors....

 

[boatpoker]

That seems to be a consistent pattern among the surveyors who publish online.

If you want to get some laughs, read the stuff by David Pascoe where he compares 2 and 4 stroke diesels.

The stuff is free but the old saw about stuff being worth what it costs certainly applies. I would suggest that new entrants in the hobby start out with manufacturer's literature and the large number of older texts and manuals produced by the Navy and commercial training schools before relying on a surveyor's blog.

As a surveyor who also publishes on line I don't disagree with you and state on my site that one should not take anything on the web at face value. Mr Hugenot is a good case in point as shown by some bizarre comments on his site like these ......

" 1. FIRST, water cannot migrate into solid fiberglass, which is why excellent yacht designers use solid resin fiberglass at the turn of the bilge keel and strut foundations and anywhere a through hull will penetrate the shell.
2. SECOND, Osmotic blisters require a cathode, that is an impurity within the laminate which draws the water in gives it an electron which changes its molecular structure and then because the water molecule is larger it can’t migrate back out of the gel coat. As this cathodes potential lessens it draws less and less water. (see my article on fiberglass blistering under white papers on this website)
3. THIRD, no one has built hulls with balsa or synthetic foam cores since the early 1980’s, there are numerous synthetic materials that can be used instead which will not later rot out. Further while these delamination conditions have lead to astronomical repair bills in the past (in those years when the blister scare was at its height), these repairs are no longer overcharged, and no one reputable boat yard strips off the gell coat any longer. Now days they just repair the blisters, and often the small repair cost is far less than the price of a moisture meter."

 

[FF]

1. FIRST, water cannot migrate into solid fiberglass, which is why excellent yacht designers use solid resin fiberglass at the turn of the bilge keel and strut foundations and anywhere a through hull will penetrate the shell.

I think you should Google osmosic blisters , and read up .

ALL GRP is water permiable , its just a matter of rate. of flow.

 

[psneeld]

1. FIRST, water cannot migrate into solid fiberglass, which is why excellent yacht designers use solid resin fiberglass at the turn of the bilge keel and strut foundations and anywhere a through hull will penetrate the shell.

I think you should Google osmosic blisters , and read up .

ALL GRP is water permiable , its just a matter of rate. of flow.

I agree...

Plus more than a few reputable repair firms/marinas still peel/grind...and if the damage is severe enough (for whatever original cause)....removal of the gel/damaged laminates to speed the drying process without the use of heaters/vacuums is the only way I read of.

 

[dhmeissner]

http://www.zahnisers.com/repair/blister/blister1.htm

Everything you wanted to know about blisters.

 

[pauloman]

more on blisters

Hull Blister Repair Options - Fiberglass Boat Repair - Boat Pox

 

[Deidra]

Cost of blister repair

Wow, just read some of this and it would scare you to death. We dealt with blisters on our sailboat at a "do it yourself" boatyard, but they were small (though numerous) and did not require fiberglass repair. Now we have made an offer on a trawler and yesterday's haulout shows blisters that require "more indepth" repair. Should we just move on to another boat and be glad that the survey only cost 1K or will ALL 25 year old Taiwanese trawlers have the same problems? From what I've read, the repair could cost 10 - 20K on a 38 foot boat!!!

 

[psneeld]

..................................

 

[Daddyo]

Blister advise?
Don't touch your skin to hot things

 

[Daddyo]

Wow, just read some of this and it would scare you to death. We dealt with blisters on our sailboat at a "do it yourself" boatyard, but they were small (though numerous) and did not require fiberglass repair. Now we have made an offer on a trawler and yesterday's haulout shows blisters that require "more indepth" repair. Should we just move on to another boat and be glad that the survey only cost 1K or will ALL 25 year old Taiwanese trawlers have the same problems? From what I've read, the repair could cost 10 - 20K on a 38 foot boat!!!

No, don't walk away yet. Get a price. Depending on the yard and how fare you want the work it won't cost nearly that. How dare you try and buy a boat without me

 

[Sceptic]

The answers you seek will not be found on a internet forum. There are as many opinions about blisters, how to repair them, and what causes them to develop, as there are posters.

Find some people in real life - pick their brains and decide if you can trust them. Remember this - there are as many different approaches to the problem (if it is a problem) as there are people willing to take your money.

I have never seen a boat sunk by blisters, but I have seen owners financially sunk by them.

Mike

 

[Larry M]

The answers you seek will not be found on a internet forum. There are as many opinions about blisters, how to repair them, and what causes them to develop, as there are posters.

Find some people in real life - pick their brains and decide if you can trust them. Remember this - there are as many different approaches to the problem (if it is a problem) as there are people willing to take your money.

I have never seen a boat sunk by blisters, but I have seen owners financially sunk by them.

Mike

Good advise and here's more. Ask the seller to be responsible for the blister job or split some of the costs. Do a hold back at closing. How bad does the seller want to sell? He can't hide the blisters for the next potential buyer if you walk.

We were on a 1985, 42 trawler the other night and the discussion came up. They split the cost of the blister job, $6,500/each when they bought their boat. He thought he got a good deal, in his opinion for the repairs were done right.

 

[Deidra]

Thanks to all for responding (except maybe guru who contributed to my fitful sleep last night! ) I have found that when it comes to boats (especially "good old boats") that there is no substitute for experience but of course everyone's experience is different.

 

[pauloman]

those tiny blisters are often just epoxy filled (epoxy cream and a putty knife). Barrier coats are just a layer of epoxy which is less porous than polyester resin. one coat of a thick epoxy paint......

 

[Blue Heron]

I wouldn't walk away. Be cautious of having the sellers yard do the work. You cannot check the progress if your in a different location. I would negotiate the repairs into the cost and do the work at your preferred yard. The survey should indicate if they are "cosmetic" or structural.

My boat had small blisters. I don't worry about it.

 

[psneeld]

those tiny blisters are often just epoxy filled (epoxy cream and a putty knife). Barrier coats are just a layer of epoxy which is less porous than polyester resin. one coat of a thick epoxy paint......

http://www.yachtpaint.com/MPYACMDatasheets/Interprotect_2000E+eng-usa+A4+Y+20120201.pdf

PRODUCT DESCRIPTION​

Interprotect 2000E is a unique two part epoxy coating, developed to protect new and used fiberglass hulls from water absorption. Due to its anti-corrosive
properties it is also ideal for use on metal.
* Contains Micro-plates​

​

® for extra protection.
* Excellent adhesion to fiberglass, composite, metal and wood.
* Long overcoating times between coats add versatility & flexibility in a boatyard environment.
* Compatible with Interlux primers, antifoulings and Interfill fairing compounds.​

Microplates® in Interprotect 2000E create an overlapping barrier to eliminate any direct path for water migration.

Number of Coats ​

​

​

Substrate priming before application of fairing compound: 1. For Blister Prevention & Anti-corrosive system: 4-5cts by​

roller, 2-3cts by spray as required to reach 10 mils DFT .

 

[healhustler]

For what it's worth, there was a full cored boat next to me here in Stuart, FL, that was sent out for a bottom job, and blisters penetrating into the glass were found in quite a few places. The guy contracted for the job ground the blisters down and did a power-wash daily for over 30 days, saying that removal of salt was the critical factor, because salt was what held the moisture. The, he used nearly 200 gallons of alcohol to force dry the hull over a period of weeks. He apparently has had previous success with this process, and the boat came back to the marina after about 7 weeks.... sold a couple of days ago. Moisture readings on the survey were in line, by the way.

 

[Deidra]

been here, done this... imagining something much worse and more expensive.... ah well, still waiting for the written survey with moisture readings. What were we thinking to schedule it on a friday?

 

[Codger2]

...ah well, still waiting for the written survey with moisture readings.

Man! Where were these gals when I was a young man? Geez!

 

[BruceK]

I agree with Blue Heron, get a reduction and have the work done; the Yard is responsible to you and the job is not shortcut to save $. Problem is,each blister has a life of its own, the work is hard to predict and cost until you get grinding.

 

[Keith]

The problem is not water or salt in the FG, it's uncured resin. The guy who washed every day with water has the right idea. The best way is to simply use a blowtorch, but for some reason yards these days don't like that process. I post cured mine with the HotVac system. Peeled, post-cured, then relaminated. About $30k 10 years ago. Hotvac Boat Hull Drying, Osmosis Treatment, Osmocure Not a blister since.