I have the pox

centerline · Nov 15, 2015

As has been shown by the people who have studied the causes and cures for boat hull blisters, and by the testimonials of rational boat owners, the blisters may be ugly, but very, very rarely are they an actual problem.
a bit of education could minimize a lot of the perceived problems in the world...

Bob J. · Nov 15, 2015

I used the same the products to fix my powerboat CloudDriver minus the extra layer of glass. It was a solid repair & I had no more issues. If Bawlmer blasts the hull any blister that has unsound gelcoat beneath it will open up & he shouldn't need to dig out any gelcoat. Hopefully you're in a yard that allows DIY. If that's the case the biggest expense would be hiring someone to do the blasting. The rest of the repair is just time/labor, not a lot of $$ for out of pocket materials.

Although no boat has ever sunk from blisters, left unchecked it will lead to structural issues with the laminate which will require peeling the gelcoat. The boat will continue to soak up water making it heaver, slower & sit lower on it's water line. That's how I suspected there was something wrong with my powerboat. As the season continued she began to sit low on her water line. Each time I walked down the dock & saw her my heart skipped a beat thinking the bilge pump had failed & she was full of water. When I pulled her in the fall I was sickened by what I saw. She was full of water only in the wrong place.

BigEasy · Nov 15, 2015

So if you decide to grind out blisters and barrier coat, I would wait until you decide to sell the boat. May improve your ability to sell at a more favorable price. If you barrier coat and haul out every winter for 5 months, you will likely have a longer period of time before the blisters return; if you keep the boat in water year round, the blisters will return in a short period of time. Unless you are fortunate enough to sell quickly, you may find yourself incurring the expense of barrier coating and still wind up with a boat with pox on a haulout survey. End result is that a potential buyer walks away or renegotiates the sale price lower.

mitiempo · Nov 15, 2015

Gelcoat peeling and barrier coating are to a great extent an industry based on fear. 99.9% of blisters are cosmetic. (Uniflite and early Valiants are the exception but for different reasons. A boat cannot absorb a large amount of water as there is not any space for it except any small voids and the blisters themselves.

Also if planning to barrier coat a hull it must be dry. Any boat that has absorbed moisture over a period of decades will not dry out in 2 weeks. More like 4 - 6 months in a dry area. Barrier coating a laminate with moisture in it will only bring back blisters. The moisture has to go somewhere.

CloudDiver · Nov 16, 2015

I know a lot of people have various opinions as well as experiences w/ blisters and how they should be addressed. One of those suggestions is also not to worry about them. I'm just going to throw out there that I think it is universally agreed that blisters kill your re-sale value.
I'm guessing the O.P.'s C-270 is early to mid 1990's, I think that is the rough window of manufacture time. If it were my boat, I'd want to address the 'Pox' in a manner by which I had reasonable assurance they would 'likely' not come back. here is a general guide to what I think would be your best option; (Keep in mind I'm not rich either, I want to save you money as much as I would if I were in your shoes)
- Your hull needs to stay out the water for the winter. Its up to you to work with your yard of choice on what this will cost. hopefully your yard allows owner work. If they don't, find a new yard!
- You need to media blast the old bottom paint off, leave gel coat on. You CAN sand it yourself, but TRUST me on this, save yourself the pain and find a mobile Soda Blaster who would do it for a fair price. The Soda Blaster I used in AZ for several jobs, and also recommended to friends, charged me a very fair price to blast my sensitive custom bike frames and parts. He took his rig to my friend's house and charged him $750 (a full day's work) to blast an ENTIRE 30 foot trailer frame. He would probably have charged the same for a boat on stands and it would be an easier job than a trailer.
- The gel coat can stay, no need to peel it. Very lightly grinding out the blisters is only needed where the glass may be weak. The test is using a pick or knife point to tap the areas. If the fibers are weak and brittle just lightly and shallow grind them. The majority of you blisters 'appear' to only have formed between the bottom paint and gelcoat, worst case between the gelcoat and laminate. Most of this will come off with the blasting. Little or no grinding should be involved.
- Let it dry out as long as possible. I know its already cold/freezing where you are. If it was possible to wait till spring thaw to haul out that is a possibility, but even in freezing temps it 'could' be beneficial to have it out of the water the whole winter even if the drying will be slow. You gotta make the call on that, its going to depend on what you are paying for yard storage. You also have to remember that part of the 'drying out' process involves spraying the hull down with water. Sounds crazy, but the its the same logic as spraying down concrete as it cures to speed and stabilize the drying process.
- In the spring, you can just sand the hull with 80 grit on an orbital palm sander to prep for paint. Use the Interlux epoxy filler I mentioned before to level off the blister divits and sand fair. Use a full two gallons of Interlux Interprotect 2000 to barrier coat the hull, just roll it on. Don't worry about orange peel look, it can be lightly sanded to smooth it. Heck, its worth the extra $100 per gallon to use 3 gallons and have a bomb proof barrier coat!
- Now bottom paint of your choice. You could probably work a deal with the yard. If the will allow the media blasting followed by drying time and the owner prep work of sanding/epoxy filler then will make money off the Barrier Coat/Bottom paint job. watch them like a hawk... make sure they use the full 2 or 3 gallons of barrier coat and don't sand too much off!

Hopefully you can work something out. $500 per foot is INSANE. I'd personally only charge you $300 per day to do the work and I could do it in 4 days total (split up between before/after drying), but that's not including the haul out, storage fees, materials.

centerline · Nov 16, 2015

CloudDiver said:
I know a lot of people have various opinions as well as experiences w/ blisters and how they should be addressed. One of those suggestions is also not to worry about them. I'm just going to throw out there that I think it is universally agreed that blisters kill your re-sale value.
I'm guessing the O.P.'s C-270 is early to mid 1990's, I think that is the rough window of manufacture time. If it were my boat, I'd want to address the 'Pox' in a manner by which I had reasonable assurance they would 'likely' not come back. here is a general guide to what I think would be your best option; (Keep in mind I'm not rich either, I want to save you money as much as I would if I were in your shoes)
- Your hull needs to stay out the water for the winter. Its up to you to work with your yard of choice on what this will cost. hopefully your yard allows owner work. If they don't, find a new yard!
- You need to media blast the old bottom paint off, leave gel coat on. You CAN sand it yourself, but TRUST me on this, save yourself the pain and find a mobile Soda Blaster who would do it for a fair price. The Soda Blaster I used in AZ for several jobs, and also recommended to friends, charged me a very fair price to blast my sensitive custom bike frames and parts. He took his rig to my friend's house and charged him $750 (a full day's work) to blast an ENTIRE 30 foot trailer frame. He would probably have charged the same for a boat on stands and it would be an easier job than a trailer.
- The gel coat can stay, no need to peel it. Very lightly grinding out the blisters is only needed where the glass may be weak. The test is using a pick or knife point to tap the areas. If the fibers are weak and brittle just lightly and shallow grind them. The majority of you blisters 'appear' to only have formed between the bottom paint and gelcoat, worst case between the gelcoat and laminate. Most of this will come off with the blasting. Little or no grinding should be involved.
- Let it dry out as long as possible. I know its already cold/freezing where you are. If it was possible to wait till spring thaw to haul out that is a possibility, but even in freezing temps it 'could' be beneficial to have it out of the water the whole winter even if the drying will be slow. You gotta make the call on that, its going to depend on what you are paying for yard storage. You also have to remember that part of the 'drying out' process involves spraying the hull down with water. Sounds crazy, but the its the same logic as spraying down concrete as it cures to speed and stabilize the drying process.
- In the spring, you can just sand the hull with 80 grit on an orbital palm sander to prep for paint. Use the Interlux epoxy filler I mentioned before to level off the blister divits and sand fair. Use a full two gallons of Interlux Interprotect 2000 to barrier coat the hull, just roll it on. Don't worry about orange peel look, it can be lightly sanded to smooth it. Heck, its worth the extra $100 per gallon to use 3 gallons and have a bomb proof barrier coat!
- Now bottom paint of your choice. You could probably work a deal with the yard. If the will allow the media blasting followed by drying time and the owner prep work of sanding/epoxy filler then will make money off the Barrier Coat/Bottom paint job. watch them like a hawk... make sure they use the full 2 or 3 gallons of barrier coat and don't sand too much off!

$500 per foot is INSANE.

I agree....
this seems like a solution that is simple and would work as well as any any, at the most affordable cost.
any large blisters SHOULD be ground out, allowed to dry, and then filled before applying the barrier coat, but overall, it really isnt much more work than doing a quality prep job before applying bottom paint....

Stu Jackson · Nov 16, 2015

centerline said:
than doing a quality prep job before applying bottom paint....

Which might be the reason for the PAINT "blisters" to begin with.

Good luck.

BigEasy · Nov 16, 2015

Way back when my boat was being repaired for pox, there was a guy with a boat next to mine that was meticulous in doing his blister job. After the gelcoat was pealed ( many large blisters), he actually fabricated a plastic film tent around the hull that allowed access beneath the boat. He placed heaters and dehumidifiers inside the tent to facilitate the drying process. And, yes he removed the plastic film about once a month to scrub the hull with a strong detergent to rid the hull of the fluids that weep from the laminate and blisters. This fluid dries on the surface of the hull and impedes the drying process. A few days after washing, the moisture content of the hull actually decreases. The objective is to get the moisture content below 10%. I have also seen a yard use large electrically heated pads with a vacuum to dry the hull and to suck out moisture and blister fluids. When you walked by, it smelled like resin that was in the process of curing. I really do believe a big factor in my repair failing was that the yard did not adequately dry the hull. Even though it remained on the hard for 5 months, I don't think that it was dry enough. That might work in Arizona; however, in south Louisiana , the winters are too wet and humid to really dry the hull without tenting, as mentioned above, or placing the boat inside a temperature controlled building. The blister job lasted 12 to 18 months before it failed. I continued to sail and faced the dilemma of selling "as is" or redoing the repair again before selling. Katrina solved the problem by damaging the boat beyond repair.

CloudDiver · Nov 17, 2015

You make an extremely critical point about the ambient temp and humidity during the drying process. This is exactly why blister repairs fail, the hull never really gets dry. The guy you mentioned who tented his hull with plastic and used heaters and dehumidifiers... If you are not in a warm, dry climate or indoors you'd have no choice but to take these steps.
I am concerned about the OP's drying cycle in the Baltimore area. Winter is basically here and its cold, not ideal for laminate drying. I think its best to go ahead and media blast the old bottom paint and shallow grind any deteriorated laminate, but as it sits on the hard from Nov to March I wouldn't expect much actual drying to occur. If it were in-doors and some heat could be applied, different story. When the sun comes out in March and you could count on 60 to 90 days of above-freeze temps and some sunshine, periodic fresh water wash downs and scrubs... Then it will probably be good to go. I'd have the moisture level checked right after media blat in November, again in March and let it really dry for 3 months and check again June 1st.

Sorry to hear you boat got eaten up by Katrina, in a way it was a blessing in disguise I suppose (I'm sure you've heard that WAY too many times). Hopefully, some day, when I get around to buying a bigger boat there will be some affordable epoxy hulls around 40 feet and then blisters wont be a concern!

BigEasy said:
Way back when my boat was being repaired for pox, there was a guy with a boat next to mine that was meticulous in doing his blister job. After the gelcoat was pealed ( many large blisters), he actually fabricated a plastic film tent around the hull that allowed access beneath the boat. He placed heaters and dehumidifiers inside the tent to facilitate the drying process. And, yes he removed the plastic film about once a month to scrub the hull with a strong detergent to rid the hull of the fluids that weep from the laminate and blisters. This fluid dries on the surface of the hull and impedes the drying process. A few days after washing, the moisture content of the hull actually decreases. The objective is to get the moisture content below 10%. I have also seen a yard use large electrically heated pads with a vacuum to dry the hull and to suck out moisture and blister fluids. When you walked by, it smelled like resin that was in the process of curing. I really do believe a big factor in my repair failing was that the yard did not adequately dry the hull. Even though it remained on the hard for 5 months, I don't think that it was dry enough. That might work in Arizona; however, in south Louisiana , the winters are too wet and humid to really dry the hull without tenting, as mentioned above, or placing the boat inside a temperature controlled building. The blister job lasted 12 to 18 months before it failed. I continued to sail and faced the dilemma of selling "as is" or redoing the repair again before selling. Katrina solved the problem by damaging the boat beyond repair.

Scott T-Bird · Nov 23, 2015

bawlmer said:
He told me he does not soda blast nor does he allow outside contractors to as he says it is too messy. Fine. I have all winter to figure this out. If I can't come to terms with this yard I will simply pass on all services, do spot repairs on the open blisters in the spring, splash, enjoy my summer and fall and haul again for the winter at another boatyard that is more flexible and get the work done then. I have a contract for winter storage with these folks. I needed to pull the boat this winter as it spent the last 2 years in the water so the money spent so far was not wasted. It is a nice secure yard to store the boat.
I want to thank every single person who responded, especially Cloud Diver for a long and very enlightening conversation. When you have this much info available it is hard for anyone to get over on you.

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Patience is a virtue! I think you are making a good decision. I'm happy that my new yard will soda blast the bottom for me this year at a reasonable price. They are going to remove the old barrier in a few weeks and suggested painting in the Spring so I'm going to have them apply new barrier and bottom paint. I'm very interested to see how the bottom looks with old paint removed. I've not seen any suspicious blisters, just a very rough surface and a few patches where gelcoat is exposed.

centerline · Nov 23, 2015

Scott T-Bird said:
Patience is a virtue!

this is absolutely true in all aspects of boat ownership.... buying, selling and everything in between.... except if the boat ever springs a leak

SailormanDan · Nov 23, 2015

+1 for Eddie's comment, our laid-back dockmaster blows up when you ask about blisters because they are mostly cosmetic in his opinion. I for one don't have $10,000, let alone spend it on a new bottom like that.