Need best advice on blister repair

[Frank Langer]

Our 1984 E30+ has been babied for most of her life, and I have kept her in great shape since acquiring her from a discerning owner 11 years ago. I have hauled her every two years, sometimes a bit more often, to check hull, renew bottom paint, etc. She has always had some blisters at the waterline in the aft quarter, but only for about 3 feet near the stern, mainly on the port side, extending only about 2 inches below the waterline. When I hauled her this time, I noticed a bit more blisters on the quarters, but also a number of blisters where there hadn't been any before, mainly on the starboard side extending about a foot or a bit more below the waterline, but none on the underside of the hull fore or aft of the keel. In total, I am counting about 80 or maybe a few more on the hull all round, most about the size of a small fingernail, a few a bit larger. There are some sections of the hull where no blisters are evident.

I have removed all the bottom paint, and I see evidence of a few, though not many, places where there has been a small epoxy repair, likely to deal with earlier blisters, though I can't tell for sure. None of these repairs are showing current blisters.

The boatyard staff, who have a good reputation, are mixed on their views. The main guy says that to be relatively (though not absolutely) sure of getting rid of them, I need to grind the gelcoat down to fibreglass, get rid of any blisters/voids, dry the hull as much as possible in this northern BC coastal environment, add 3 - 4 coats of Interprotect 2000 and bottom paint. A couple of other staff are suggesting just grinding out the existing blisters and filling with epoxy, coating with Interprotect, and dealing with any new blisters at each haul out, indicating that it's a 33 year old boat, albeit in great shape.

Yard staff have started to grind down the gelcoat from the bow back, and in the first third of the boat from the bow going aft, there are only 4 blisters, though I can see a few more in the upcoming mid section that hasn't been touched yet, and the other side of the hull has more.

I am leaning to have them grind the gelcoat down to the fibreglass, filling any voids and coating with Interprotect 2000 to minimize the possibility of blisters returning, but this is a very expensive process. The other option is to grind the gelcoat to where I can clearly see where there are blisters, then filling those on a spot basis and coating with Interprotect 2000. This option would be much less expensive, but has the risk that new blisters that are currently developing but not obvious will appear at each haul out. The one staff asked me: "why remove perfectly good gelcoat anywhere there aren't signs of blister?", but if they are showing up nearby, are they also lurking in the blister free areas?

I am looking for your best advice on what approach you would take, drawing on your wisdom on this site, and especially if you have done any work on blisters on your boats, and how that has developed over the years.

Thanks for any help with this! I need to make a decision in the next couple of days, as the yard staff await my direction on how to proceed. I am currently 66 years old, in quite good health, and plan to sail for at least the next five to ten years, and love this boat for so many reasons, so I want her to last--she is my passion!

Frank

 

[Rick R.]

Frank,

We have seen a few small blisters with each haul out.

The staff at the boatyards as well as a boatbuilder have told me to repair the ones that open during sanding. They are faired, sanded smooth and painted over.

Six in years now and never a problem.

I know I've read here of folks having the "bottom peel" at a hefty cost (I was quoted $7k) but the blisters are not an issue.
Rick

 

[toddster]

Hard to figure when someone else is doing the work and charging for the time. I hauled Arcturus home, sanded the bottom all down did the IP2000 thing. Most of the little blisters just disappeared during sanding process. Maybe a dozen were large enough to actually repair. Plus there were a couple of old questionable repairs to be ground out and redone. And some old grounding damage to repair. I certainly feel better for having done the whole bottom. But it took a couple of months, and the boat spent the whole summer out in the dry Eastern Oregon heat and thoroughly dried out.

There's a Danish guy with a YouTube channel who dried his boat in the winter by essentially vacuum bagging a greenhouse heat mat onto the hull (after sanding) and moved it to a new patch every day. According to his moisture meter it worked pretty well - still seemed to take a month.

Seems like it would be disastrously expensive to pay a boatyard to do these things to an old boat.

 

[RMX]

Grind and fill

When I hauled last season Lucia had 42 blisters ranging from a dime size to a quarter. She had been sitting stagnant at a dock for three years. Circle them with a sharpie as soon as you haul because they may easily dry out and shrink before you begin to do the work. I used a 4" circular handheld grinder. Brush grinder against the blister until it opens and follow the Coca Cola colored liquid until you hit dry area. Wear proper eye and face protection, this solution has an acidic smell and quality. I filled with Interlux watertite 2 part epoxy. Very easy to work with. After drying for a day I sanded smooth and used a bottom paint common to Long Island sound to cover, do not use barrier coat with epoxy. Worked like a charm. I have difficulty seeing where I did the work.

Took home the first place trophy for Wednesday night races this summer with some pretty challenging competitors. Fast and smooth.

Rod
E36-RH
Lucia
Guilford Ct

 

[bolbmw]

I'd read some of the articles here to get more information, http://www.yachtsurvey.com/blisters.htm but, agree with the fill em when you find them approach. http://www.yachtsurvey.com/moreonblisters.html.htm too

 

[Loren Beach]

I'd read some of the articles here to get more information, http://www.yachtsurvey.com/blisters.htm but, agree with the fill em when you find them approach. http://www.yachtsurvey.com/moreonblisters.html.htm too

While Pascoe is probably right about some things, I really do know a top-rated surveyor that considers many of his opinions to be idiotic.
I recall that about a decade ago he published an essay (now removed) that questioned why sailboats needed keels.
I suspect that many of his findings concerning power boats are apt, but that he has little sailboat experience.

One of the links contains his opinion that builders skimp on resin quality and constantly change suppliers. I knew two of the three founders of Yacht Constructors in Portland, builders of Cascade sailboats for many decades, and they used quality resin and would not change to save a buck. Even their boats with all roving and hand layup would sometimes blister all over the bottom later. There are a lot of environmental (temp. and humidity) variables in doing layups and I have seen extensive blisters on a few Ericson's as well.
My friends in the repair business seem to believe that no builder (!) is immune to it. Heck, I saw a lovely Baltic 38DP, on the hard up in Tacoma, many years ago that a friend had acquired on the cheap because it had extensive blistering. He laid new glass with epoxy on the whole bottom and when done it was once more a valuable boat. The interior woodwork was amazing, BTW.

When we found a small patch of blisters (maybe a foot by 3 feet on side of the bottom pf our boat in our first few years of ownership, we also ground 'em out, filled and faired.... and they did not come back.

 

[bolbmw]

Questioning why a sailboat would need a keel is pretty damning and I was unaware of such an article, but I can't find fault in anything he's said about blisters. There are definitely a large number of factors which would influence one hulls layup over another to be more prone to blistering, and there is certainly a significant difference between a lot of small blisters (the pox) and structural large blisters.

From my boat buying experience, they all have em at this age and a boat which has been peeled and repaired won't sell for more than one that has had spot repairs. If my boat had the pox I'd fill and monitor every couple years and wouldn't be surprised at all if/when I remove all the previous bottom paint to find previous repairs. You'll never get back the investment in peeling the hull.

 

[Christian Williams]

In 2016, the previous owner of my boat had the bottom stripped and barrier coated and bottom-painted at Marine Shipyard in Long Beach, a full-service facility.

Cost: $15,000. They tent the boat, workers in hazmat suits, all poisonous materials required filtered fans, and so on.

In my opinion, this is one of those jobs that gets stuck in your head like a tune that won't go away, and to get rid of it all you can do is write a big piece of money to regain peace of mind.

I've fixed lots of blisters, often cutting corners in the rain with non-recommended materials and to the point where I stopped caring how good a job I was doing, but when the boat was launched I felt better. I don't think the boat even cared.

 

[Frank Langer]

Update on blister repair--still underway but making progress!

Hi,

I have read all your replies and recommendations, as well as lots of info on the internet, and talked with local folks, both lay sailors and professional workers of various sorts. I have decided to ask them to begin to grind off the gelcoat to see how things looked as we did so, and to assess the underlying fibreglass. As they did so, it is obvious where the larger (a few about quarter size) blisters are, then there are a fair number of dime size ones that also show up clearly. I can also see where there had been a very few earlier repairs of blisters, and those are solid and not re-blistering. But I also began to see a number of very small (pin head size) that were not visible when the gelcoat was still on, but are visible with the gelcoat removed, and show as just a pin-prick size dot of moisture. I think if these were left without stripping the gelcoat, they would become future larger blisters.

So, with one side of the gelcoat removed with three days of grinding, so about another three to go to remove all the gelcoat on the hull, I am significantly more broke, but I think I've made the right decision to strip the gelcoat, recoat with Interprotect 2000 (about 4- 5 coats they recommend), add a couple of coats of bottom paint and then re-launch. If I had done spot repair by grinding out the visible blisters and filling with epoxy I would have effectively done the current blisters, but would not have seen the smaller ones that only revealed themselves when the gelcoat was removed.

I think this will be a more long term repair. We'll see...

Comments welcome!

Frank

 

[bolbmw]

They say you can't put a price on piece of mind, so I'm sure you made the right choice.

 

[frick]

The POX

Hi,

I have read all your replies and recommendations, as well as lots of info on the internet, and talked with local folks, both lay sailors and professional workers of various sorts. I have decided to ask them to begin to grind off the gelcoat to see how things looked as we did so, and to assess the underlying fibreglass. As they did so, it is obvious where the larger (a few about quarter size) blisters are, then there are a fair number of dime size ones that also show up clearly. I can also see where there had been a very few earlier repairs of blisters, and those are solid and not re-blistering. But I also began to see a number of very small (pin head size) that were not visible when the gelcoat was still on, but are visible with the gelcoat removed, and show as just a pin-prick size dot of moisture. I think if these were left without stripping the gelcoat, they would become future larger blisters.

So, with one side of the gelcoat removed with three days of grinding, so about another three to go to remove all the gelcoat on the hull, I am significantly more broke, but I think I've made the right decision to strip the gelcoat, recoat with Interprotect 2000 (about 4- 5 coats they recommend), add a couple of coats of bottom paint and then re-launch. If I had done spot repair by grinding out the visible blisters and filling with epoxy I would have effectively done the current blisters, but would not have seen the smaller ones that only revealed themselves when the gelcoat was removed.

I think this will be a more long term repair. We'll see...

Comments welcome!

Frank

I seem to remember reading that it was in the late 70s early 80s that a fire retardant was added to the resins, and this helped create the problems of blisters. Of course the OPEC gas embargo drove the prices mad and other short cuts were also taken. My 1971 E29 has never had a blister, Thanks be to God.

I had a friend whose Tartan 34 was prone to blisters. Every Spring we would open the new one, dry and fill with Polyester puddy. It was way cheaper than a full strip down. and it worked.

Rick+

 

[Loren Beach]

I seem to remember reading that it was in the late 70s early 80s that a fire retardant was added to the resins, and this helped create the problems of blisters. Of course the OPEC gas embargo drove the prices mad and other short cuts were also taken. My 1971 E29 has never had a blister, Thanks be to God.

I had a friend whose Tartan 34 was prone to blisters. Every Spring we would open the new one, dry and fill with Polyester puddy. It was way cheaper than a full strip down. and it worked.

Rick+

Only one (major) builder that I know of, for sure, was Uniflite, builders of the Valiants. The chemical would attract water inwards from the surface and some of the late-70's Valiants had pronounced blistering all over above the waterline. Yup, even the cabin sides.
Some friends of ours bought one of those (no blisters when they bought it) and had to refinished all of the outer gel coat. Huge project, but they were determined, and got it done and then went cruising full time for ten years.

 

[toddster]

I've looked closely at one of those blistered Valiants. They are in a class all by themselves as far as blisters. Well, along with some Vietnam Patrol Boats made from the same stuff. Some of them are two inches deep! I guess the good news is that the hull is thick enough to accommodate a two-inch blister. Available information seems to be restricted or conflicting due to a big lawsuit over the incident. What I took away from it was that these don't really have anything to do with the regular osmotic blisters. More a matter of incompatible copolymers. It sounds as if some people have paid for enormously expensive repairs - on the assumption that what works for osmotic blisters would work for the Valiants - and have been hugely disappointed. Or else they basically built a new thin fiberglass hull on the outside of the thick Valiant hull.

I was trying to convince myself that after almost 40 years, the fire retardant would have done all the migrating that it's gonna do. But it would have taken quite a few more kilobucks discount to advance that argument.

 

[Frank Langer]

Second update on blister repair

As this has turned into quite a significant repair, I am providing another update in the hopes that it might help someone in the future when faced with the decision on how to proceed if they discover blisters in the hull.

The yard workers have now ground off the gelcoat on the entire hull. It took me three days with a wood chisel to remove the existing dozen coats of bottom paint, and then the yard worker took six days with a grinder to remove the entire gelcoat. The starboard side was a bit worse than the port side, with more blisters than the port side, and there are more in the first foot below the waterline than lower in the hull. I would have thought that the greater water pressure at increasing depth would result in more water permeating the hull lower down, but it doesn't look that way.

With the gelcoat removed, it's fairly easy to see the lighter coloured spots of the blisters. Grinding them out with a dremel works well. Some only need slight grinding to remove questionable surface and get to solid underlying fibreglass, but there were a few that we ground down by about 1/8" into the fibreglass. In a couple of them, though not more, we could clearly see some delamination--I could poke my fingernail and the fibreglass matting moved in a bit and released a drop or two of water each time. So clearly, some of the blisters were not just in the bottom paint, nor just between the gelcoat and the underlying fibreglass, but had actually penetrated into the hull itself.

As well, there are a lot of pinhole size spots where a very small amount of water is seeping to the surface--not enough for even one drop, but noticeable and when I wipe my finger across, it leaves a slight wet mark. The gelcoat on the port side has been removed for nearly a week, and there is still water coming to the surface of the hull.

With all (we think and hope) of the blisters opened up with the dremel, we will leave it for a few weeks to dry out, maybe putting a fan inside the tented area to expedite drying given the time of year and current temperatures and anticipated rainfall. They will check the hull with a moisture metre to monitor the drying, and then eventually coat with 4 - 5 coats of Interlux Intrprotect 2000 and then a couple of coats of bottom paint.

At this point I still think I did the right thing to remove the gelcoat, clearly see the blisters and deal with them, allow the hull to dry more effectively than with the gelcoat in place, and hopefully re-coat with Interprotect epoxy paint once it's dry enough. The question then will be whether any blisters show up in the coming years.

This boat is 33 years old, sailed year round near Vancouver Island in salt water, and has never had the gelcoat removed, though I think there is evidence of just a few blister repairs when I removed the bottom paint. The only previous sign of blisters since I bought her 11 years ago was a small area on the port side right at the water line to about 2" below the water line, about a 3 foot strip forward from the stern. This area had quite a few very small blisters about the size of a pencil eraser on the end of a pencil. But there was no sign of blisters anywhere else on the hull until the current haulout. However, the previous owner had applied 3 coats of Trinidad SR epoxy bottom paint, and I applied an additional 2 coats of Micron CSC bottom paint every two years, so the dozen coats of paint may have either protected the hull somewhat, or hid the developing blisters underneath.

As some of you may know, I have "babied" this boat since buying her 11 years ago and she is in very good shape and sails really well in a wide range of conditions. The last two surveys I had done for insurance purposes (in 2011 and in 2016) had no recommendations for repairs, which seems to be quite unusual for an older boat. If she were not in such good shape, or if I planned to sell her anytime soon, I might not have taken this more thorough and costly approach.

I hope this information helps someone some day when faced with the decision whether to ignore blisters, spot repair a few blisters or remove the bottom paint, gelcoat and then refinish the hull as I'm doing.

Frank

Frank

 

[Christian Williams]

It is a mighty fine thing to have the right boat, one you can keep with pride.

And you have to know something about boats to really know it.

 

[rgraham]

Wash the hull

I have a 36 RH that had severe blistering. 80 – 100 plus blisters the sizes ranging from 1 to 3 inches in diameter and the depth 3/16 into the fiberglass. I had the hull peeled down to dry resin saturated fiberglass about 3/16. There was a lot of glass (which was peeled) that lacked enough resin in it, for lack of better words it was dry and fibrous. I read as much as I could find about blister repair and the guy who peeled the hull had seen a lot of blister repair work done. He recommended that I wash the hull with soap and water every day for a month, which I did. Some of the repairs that yards do that I read about use a high heat pressure washer (like a steam cleaner) for this process. The reason for this is the acid like substance that forms in the blisters is somewhat like ethylene glycol and needs to be removed from the fiberglass strands by washing the hull. If not removed it can cause the new material being applied to the repair not to bond. I noticed that the smell went away after the repeated washings. I then let the hull dry for 18 months and went back with two layers of 1608 fiberglass and epoxy resin, vacuum bagging it to the hull. I faired the hull and applied 4 coats of Interlux 2000 so far. I did all of this work myself because I couldn’t have afforded to pay someone to do it. It has been the hardest thing I’ve done to date both physically and mentally, I’ve been tempted to quit many times. For me the fairing process was the hardest because it is the most time consuming and the hardest physically due to all of the hand long board sanding required.

 

[Frank Langer]

Thanks very much for this useful information. Being in the middle of this process now, I can really understand how upsetting and exhausting this is! I am very hopeful that the end result will be worth it, knowing that the hull is fully repaired, sealed and free of any blisters. People tell me that if done correctly, it will be better than new, due to the interprotect 2000 barrier coat. Our boat has been pampered and so is otherwise in very good shape, so she is worth investing in to keep her at her best.

Did you use a moisture meter to determine if the hull had dried enough to proceed with recoating, or how did you decide? Are you still working on your repair or have you finished now?

Thanks again for your reply!!
Frank

 

[u079721]

I have a 36 RH that had severe blistering. 80 – 100 plus blisters the sizes ranging from 1 to 3 inches in diameter and the depth 3/16 into the fiberglass. I had the hull peeled down to dry resin saturated fiberglass about 3/16. There was a lot of glass (which was peeled) that lacked enough resin in it, for lack of better words it was dry and fibrous. I read as much as I could find about blister repair and the guy who peeled the hull had seen a lot of blister repair work done. He recommended that I wash the hull with soap and water every day for a month, which I did. Some of the repairs that yards do that I read about use a high heat pressure washer (like a steam cleaner) for this process. The reason for this is the acid like substance that forms in the blisters is somewhat like ethylene glycol and needs to be removed from the fiberglass strands by washing the hull. If not removed it can cause the new material being applied to the repair not to bond. I noticed that the smell went away after the repeated washings. I then let the hull dry for 18 months and went back with two layers of 1608 fiberglass and epoxy resin, vacuum bagging it to the hull. I faired the hull and applied 4 coats of Interlux 2000 so far. I did all of this work myself because I couldn’t have afforded to pay someone to do it. It has been the hardest thing I’ve done to date both physically and mentally, I’ve been tempted to quit many times. For me the fairing process was the hardest because it is the most time consuming and the hardest physically due to all of the hand long board sanding required.

This a really interesting point. Long time readers here will remember that I had a failed blister repair on my Ericson, which actually failed several times. And I always wondered if perhaps the surface, though adequately peeled and prepped, was somehow just not giving a good bond for the epoxy coating that was applied. And yes, if you have unreacted resin and styrene in the hull and on the surface, you essentially have the hull coated with mold release, so that the epoxy does not get a good bond to the hull, and can easily lift off. The solution would be to wash the hull often, even though it does seem counter intuitive to be adding water to the hull to get it to dry out. This water can wash away the water soluble portions of glycol and dibasic acids, but probably won't remove everything, especially the styrene. Which is why using soap, or even solvent, would help the process. As to the use of a moisture meter, I'm not sure that's entirely adequate, as a resistance moisture meter may not respond to the present of glycols.

 

[rgraham]

I didn't use a moisture meter

I figured after 18 - 24 months it would be as dry as I would be able to get it. I lucked out last year when I stared putting on the fiberglass because we had a drought and I was able to get all the glass on without it raining during the process. For me when I was fairing the hull I kept chasing "making it better". So it is an unending process, I finally just had to quit and say good enough. The shadowing in the photo is from the rolling on of the Interlux, it is actually better looking than this photo appears. That's my story and I'm sticking to it.

 

[Frank Langer]

Wow, that looks pretty good now! Good job!
Frank