I have a question regarding blisters....

[Cathy Monaghan]

What is the best method to repair the hull of a blistered boat? I've already removed the bottom paint and ground out the blisters.


Thanks,
Cathy

[moctrams]

I would reccommend "soda blasting" of the hull, followed by a drying period and then applying a barrier coat. I have done the West System on a Cal 29 previouly owned and now folks in my harbor have gone to the Interlux's Interprotect 2000.

http://shopping.yahoo.com/817024128-200 ... -gal-gray/

[David van den Burgh]

Cathy,

I suppose the right answer would depend upon the extent of the blistering. How many blisters are we talking about? All over the hull, or in a few areas? If it's isolated, as we've experienced with Ariel, I grind it out to a solid substrate, water rinse and clean with acetone to ensure it's dry, then fill either with thickened epoxy (on a shallow blister) or with fiberglass patches cut to size and laminated in place with epoxy. I believe that's pretty standard. If you haven't picked up the West System Epoxy Fiberglass Repair Guide, you might want to get one.

Good luck.

David

[Steve Laume]

Cathy, I saw your pics and I believe you are beyond the soda blast and barrier coat.

Everything I have read on blisters stresses complete drying as a priority. Realization has been out more than six months so she should be dry if well covered. A final, localized drying with a hair dryer couldn't hurt. wipe with solvent to remove all wax and debris. This will also have a drying effect. If your grinding is deep enough to allow it, some glass wetted with epoxy will help fill out the void and ensure the strength of the repaired area.

I know when we talked you had some doubts about the West System fillers being water proof. I read through everything and found no cause for alarm. Some sort of filler mixed with epoxy will be key to the final fairing and finish of the blistered areas. One of the high density fillers could be used to get close to the original hull shape. The thickened epoxy should be mixed stiff and applied with a wide plastic spreader to conform to the hull. You could also lay a piece of waxed paper over the repair area and tape on a stiff but flexible material over it to form the shape. The flexible material should be a good bit larger than the repair to get a fair bend. This works best on convex areas with a simple curve. Props, wedged against the cover can help with concave surfaces. The final fairing is best done with a low density filler that is more easily sanded. A long flexible sanding board will help a great deal to get the proper shape. Once you are satisfied with the fairing of the repaired areas a barrier coating of the entire hull is probably a good idea.

Most of this information is gleaned from rather extensive reading. West has some great guides to working with their materials and there are lots of books that address blisters. I did get some actual experience with hull fairing from patching up a number of old through hull openings on various boats.

Its time to get things patched up and Realization back in her element, Steve.

[Cathy Monaghan]

Thanks everyone.

I posted that topic as a "sample" post since I was in the middle of creating some "how tos" for this new message board. If you're wondering where the "how tos" are, you'll find them in the "About this board" forum of this board. Anyway, I left my sample topic online since I figured it was a good question and the answers would benefit everyone.

If I get a chance, I'll post some photos of Realization's bottom for those that haven't already seen them.

Thanks again,
Cathy
Webmaster - CDSOA, Inc.
CD32 Realization, #3
Rahway, NJ
Raritan Bay

[bottomscraper]

I have no personal knowlege but you can download the West System "Gelcoat Blisters Diagnosis, Repair & Prevention Guide"
free from the web site:

http://www.westsystem.com/ss/use-guides/

[Cathy Monaghan]

Thanks Rich. I've actually been following the instructions/guidance in the Don Casey's book "This Old Boat". All of the bottom paint has been removed and all of the blisters (there were ALOT) have been ground out. Now we're waiting for those area to stop oozing. And yes, they are still oozing. Hopefully it will be finished with the oozing by Spring.

Some of the areas that have been ground away will have to be repaired with fiberglass, others can just be refilled and faired. And then the entire bottom will get a barrier coat. But I'm still mulling over which products to use. I still have a few months to make a decision.

By the way, I'm actually concerned about the new bottom paint -- what to pick anyway. Washington State has already banned the use of bottom paints containing copper and California will be next. It's just a matter of time before it will be banned all over. I don't want to have to go through removing all of that paint again. So I need to do some research on the new paints that don't contain copper. So if anybody has used any of these new paints yet, I'd like to hear from them.

-Cathy

[Sea Hunt Video]

By the way, I'm actually concerned about the new bottom paint -- what to pick anyway. Washington State has already banned the use of bottom paints containing copper and California will be next. It's just a matter of time before it will be banned all over. I don't want to have to go through removing all of that paint again. So I need to do some research on the new paints that don't contain copper. So if anybody has used any of these new paints yet, I'd like to hear from them.

Hello Cathy:

I know you say that you would prefer a bottom paint without copper. Understanding that, I would still extole the benefits of Sea Hawk Tropikote. I used it on my Typhoon Weekender (S/V Tadpole). We applied two (2) coats. It lasted more than two (2) years and that was with her being in the warm, nutrient rich waters of South Florida.

It worked very well, so well that I applied it to my Cape Dory 25D (S/V Bali Ha'i) in November 2011. Admittedly, too soon to give a grade but I am confident it will perform as well as on S/V Tadpole.

In terms of "banning copper", I know it may happen someday but I doubt it will be in my lifetime. As young as you are, it may well be in your lifetime. But, by then, you may well want to "soda blast" again if you have not by then sold S/V Realization for a Cape Dory 36.

[sloopjohnl]

Cathy,
if there is still oozing, you may have to apply heat somehow if you want to get back in the water asap. i had to strip all the gelcoat from my ty below the water line. i tented the bottom and installed four heat lamps to hasten the drying. followed with west system and barrier coat. its been waterproof since 1990, so my money is on west system.

[Cathy Monaghan]

The blisters have been ground out, open and oozing since November. We probably won't be getting them closed up until May, maybe even June, by then the boat will have been drying out for nearly 6 months. Hopefully that'll be enough time.


-Cathy

[CruiseAlong]

I had a lot of blisters on my 85 CD26 starting at 2 yrs of age. I am happy to say that blisters on the same boat is very rare these days. That first year I opened all blisters in the fall. Since mine did not extend beyond the mat layer under the gel coat (i.e. it was not into the laminate lay up), I opened the blisters down to the laminate removing only the gel coat layer until good (non purple) mat was seen. This usually meant a quarter size gel coat removal. I had hundreds to do. I removed all of the bottom paint, opened the blisters, cleaned them out with acetone, and left it for the winter....spring came and I filled with two part epoxy filler, applied Interlux 2000 and repainted bottom. Next year I HAD just as many blisters again.
So a new approach was taken. I opened the blisters, cleaned and dried as before...but did not remove the bottom paint. I let it dry over the winter, I then used West 105 to seal the laminate on the exposed laminate in each of the specific blisters and then filled with two part epoxy filler. After that the blisters from year to year decreased substantially by approximately half each year until there was nothing left. That was even though the boat was left in the water for multiple years. At that time no one would "warrant" their product or workmanship would be a lasting solution even though the work would have been at great expense.
Dana

[boogie]

In my opinion, the way to go is to start with Soda blasting or bead blasting to expose all the voids behind the gellcoat. During Layup air bubble got trapped between the gellcoat and the epoxy. Now you have voids ranging in size between pinhole and quarter inch in diameter. In time this voids fill with sea water and become blisters.
After exposing the voids you have to clean and fill them with West System while listening to the Beatles "A day in the Life" . To find all of them you have to use lamp very near the boat. After few rounds of "filling and sanding" it is time to start with the inter protect coating as per instruction. After the first coat you will find more holes to fill. Epoxy paint shrinks around the hole and expose it. Fill and sand those holes and continue with the paint. Don't forget to paint the first bottom paint layer after you finish to paint the last coat of inter protect layer while the paint is still "tacky". I used a different color so I can see when my bottom paint needs another coat.
Fair Winds,

[Matt Cawthorne]

Cathy,
If your blisters are weeping at all, hit the boat with fresh water every once in a while. While this may seem counter intuitive, the stuff that oozes out, actually attracts water out of the air and stays moist. A good rinse once in a while actually speeds things up. I used West system on my blisters the year I bought my boat (1993) and must have filled a hundred, mostly small blisters that year. I have never had a problem with any repair that was filled with epoxy. Any recurring blisters were associated with areas that were not previously repaired. When it comes to stopping water from getting into plastic, there is really only one thing that can stop the water. That is metal. Every plastic (polymer if you prefer) transmits water. Epoxy transmits water at about 1/10 the rate of polyester and saturates at a lower moisture content. I say that with a bit of caution, because badly mixed epoxy is not going to give the protection of properly mixed epoxy. NEVER make a 'hot' mix of epoxy by adding extra hardener to get it to cure faster. Buy a hardener that is designed for the temperature that you are working.

Also, if you do tent the boat at some point, and use heat, be certain to cover the ground with plastic and allow for some ventilation. Otherwise the humidity in the tent can quickly reach 100% and be worse than not tenting.


Matt

[tmsc]

Cathy,

Have you had a blister problem in the past and if so how many do you estimate? If you have a significant problem, you may actual want to invest in a peeler. If you look online you can find some good ones rather cheap compared to what a yard will charge you to do the job. They are not hard to use. If you do that look around in your area and see if anyone nearby does hot vac. This seems to be the best fix so far and when you consider the amount of time it will save versus paying for lay time in the yard it may be worth it to you. http://www.hotvac.com/

[Zeida]

[img][/imghttp://s214.photobucket.com/albums/cc263/zeidacecilia/Blisters/[img][/img]

Cathy, when I bought Bandolera and sailed her for a whole year, at that first haul out I was terrified to find out that I had the "blue ooze" sickness...remember that? When everyone here was wondering what was that all about? As I found out, they were Blisters with a capital B. I started researching and reading all about how to fix the problem. Yes, get the boat on the hard, do a total "peel" keep her for at least 5 months under a heated tarp to dry the hull out, then barrier coat, then apply the bottom paint. All of this was too expensive for me... too lengthy... too complicated, and I could not afford any of it. A fellow sailor from my slip -who has been Bando's mechanic all these years- suggested we drill out every single blister. So he, on one side with a Dremmel, and me on the other side, we drilled out at least over 1000 dime sized blisters each, some in clusters. When we had all the blisters drilled out, -took us four days of careful drilling- we would wash the boat out thoroughly each morning for 5 days...she would dry overnight...we would do it again the next day and so on. The last day we sprayed acetone all over, then we let it dry through the weekend. Coming Monday, he started filling all blisters with Interprotect 2000. After a couple of days of drying out, we then applied the Trinidad SR75 antifouling bottom paint, and relaunched. We have done that every 3 years since, and Bando is still floating. I haul out every 3 years. Yes, some minor small blisters reappear each time, but less than 10 on either side. So that first big band-aid repair has held so far.

With your boat on the hard for so long, the hull must be already dry... if still oozing, keep washing it with soap and fresh water. I'm sure by spring, she will be good and dry. Barrier coat it and apply the antifouling paint. You should be good to go.

zeida