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Blistering

Prairie Schooner

Jeff & Donna, E35-3 purchased 7/21
Ksmt bottom 2024_3-27 6003.jpg
One of this year’s projects is stripping the bottom to the original surface (gel coat?). I’m scraping off what must be at least two decades of bottom paint in most places. This photo shows the tools I’m finding most useful.
Ksmt bottom 2024_3-22 5954 sm.jpg

There isn’t a Master Thread on bottom painting or repair as of this writing. This thread seemed to have a wider variety of perspectives so I thought it would be a good place to leave some breadcrumbs. These are the posts I’ve found helpful:

- https://www.interlux.com/en/us/paint-guide/BW058-how-to-fully-repaint-grp-frp
- https://www.interlux.com/en/us/paint-guide/BW057-how-to-fully-repaint-bare-grp-frp





After reading all this, and more, the plan is to sand the rest down, patch any dings/scratches with filled epoxy, fair the keel, apply barrier coat (2-4 coats), then bottom paint. I used Total Boat Total Protect over the transducer and strut work and that seems to have held up well, so that’s what we’ll use for barrier coat. For bottom paint we picked up Micron CSC, black. We’re doing the rudder in white again.

Ambience.
Ksmt bottom 2024_3-22 5956 sm.jpg
 

Prairie Schooner

Jeff & Donna, E35-3 purchased 7/21
Fortunately I haven’t come across any medium or big blisters. There are a multitude of small blisters, around 1/8” in diameter. Also fortunate, they all seem to be dry.



Ksmt boot strp 2024_3-19 5938.jpg

This leads me to believe the white stripe is gelcoat.

My Question is about the white boot stripe. I’d like to be as minimally invasive with it as possible. I’m thinking of just filling any popped blisters with white gel coat and lightly sanding. Is there any reason not to do that? Would you recommend something else? Below the waterline I’ll patch with filled epoxy.

(We’ll consider raising the boot stripe at some point, but for now I just want to get the bottom back to good, original condition.)

Thanks,
Jeff
 

PANorth

Member II
I’m thinking of just filling any popped blisters with white gel coat and lightly sanding. Is there any reason not to do that? Would you recommend something else? Below the waterline I’ll patch with filled epoxy.
Among the abundance of blisters we repaired over the past couple of years were old repairs of small blisters. It appears that these were filled as you propose. Water had penetrated around many of these. Of course I cannot vouch for methods as it was long before I owned the boat. Perhaps flaring the edges is important.

As an update on our work: We used CopperCoat as "bottom paint". The system, as we applied it, includes two layers of barrier coat (supplied by CopperCoat) and four layers of CopperCoat. The boat has been in the water since November. Repair of a leaking fuel tank kept us from sailing through the PNW winter. But we are refilling the tank today after an epoxy repair and hope to sail in the next couple of weeks for the first time since owning the boat. Yeah!

Below is a picture of the pit corrosion in the tank. There was a clear distinction between the area with corrosion and clean metal. We coated all areas with corrosion with two layers of epoxy. It was all within reach of the port. I'm not a weight lifter so I could fit my arm into the port. We will report on all of this as we put it to use.

IMG_8228.jpeg
 

peaman

Sustaining Member
What a challenging project, to strip the entire bottom. On a 41 foot boat near me, the owner has spent 10 days or more so far, 5-6 hours per day, over the course of a few weeks, with an orbital sander attached to a shop vac, as he works back to a specific prior coat, sometimes lying on his back on a bench as he works around the keel. And then yesterday, the 40 footer next to him had a polyethylene skirt clamped to a plastic sheet ground cover, with a truck bearing signage "Billings Media Blasting" parked alongside, while the crew was rigging hoses to the tent formed under the boat. About 4 hours later (and reportedly $5000), the truck crew was finished blasting ground walnut shells at the bottom, right to the layer requested by the owner.

I hope your project is completed swiftly and to great satisfaction.
 

Prairie Schooner

Jeff & Donna, E35-3 purchased 7/21
What a challenging project, to strip the entire bottom. On a 41 foot boat near me, the owner has spent 10 days or more so far, 5-6 hours per day, over the course of a few weeks, with an orbital sander attached to a shop vac, as he works back to a specific prior coat, sometimes lying on his back on a bench as he works around the keel. And then yesterday, the 40 footer next to him had a polyethylene skirt clamped to a plastic sheet ground cover, with a truck bearing signage "Billings Media Blasting" parked alongside, while the crew was rigging hoses to the tent formed under the boat. About 4 hours later (and reportedly $5000), the truck crew was finished blasting ground walnut shells at the bottom, right to the layer requested by the owner.

I hope your project is completed swiftly and to great satisfaction.
Thanks Steven.
I've done a fair amount of bottom sanding on friends' boats. I think the scraping is a lot faster. I'm only good for a couple hours at a time, though. We put in a few days last fall and I've been heading to the yard off and on since February. It was cold and blowing stink today so I worked inside the boat. Donna kept suggesting the blasting, but I told her I'd rather spend the money on a spinnaker pole. We'll see if that math works out.
 

Prairie Schooner

Jeff & Donna, E35-3 purchased 7/21
Among the abundance of blisters we repaired over the past couple of years were old repairs of small blisters. It appears that these were filled as you propose. Water had penetrated around many of these. Of course I cannot vouch for methods as it was long before I owned the boat. Perhaps flaring the edges is important.

As an update on our work: We used CopperCoat as "bottom paint". The system, as we applied it, includes two layers of barrier coat (supplied by CopperCoat) and four layers of CopperCoat. The boat has been in the water since November. Repair of a leaking fuel tank kept us from sailing through the PNW winter. But we are refilling the tank today after an epoxy repair and hope to sail in the next couple of weeks for the first time since owning the boat. Yeah!

Below is a picture of the pit corrosion in the tank. There was a clear distinction between the area with corrosion and clean metal. We coated all areas with corrosion with two layers of epoxy. It was all within reach of the port. I'm not a weight lifter so I could fit my arm into the port. We will report on all of this as we put it to use.

View attachment 49603
Thanks for the feedback, Phil and Amanda.
When you get more info on the tank repair, it would be a great help to the collective wisdom here to document it in a thread. I've been using this one:
- https://ericsonyachts.org/ie/threads/e35-3-replacing-fuel-tank.17731/#post-156979

Jeff
 

Pete the Cat

Member III
View attachment 49598
One of this year’s projects is stripping the bottom to the original surface (gel coat?). I’m scraping off what must be at least two decades of bottom paint in most places. This photo shows the tools I’m finding most useful.
View attachment 49599

There isn’t a Master Thread on bottom painting or repair as of this writing. This thread seemed to have a wider variety of perspectives so I thought it would be a good place to leave some breadcrumbs. These are the posts I’ve found helpful:

- https://www.interlux.com/en/us/paint-guide/BW058-how-to-fully-repaint-grp-frp
- https://www.interlux.com/en/us/paint-guide/BW057-how-to-fully-repaint-bare-grp-frp





After reading all this, and more, the plan is to sand the rest down, patch any dings/scratches with filled epoxy, fair the keel, apply barrier coat (2-4 coats), then bottom paint. I used Total Boat Total Protect over the transducer and strut work and that seems to have held up well, so that’s what we’ll use for barrier coat. For bottom paint we picked up Micron CSC, black. We’re doing the rudder in white again.

Ambience.
View attachment 49600
I would suggest caution with the idea of a barrier coat unless you are going to strip all the gelcoat off and recover with glass. The problem is that your moisture (and this is true of most blisters I have seen) are between the gelcoat and the fiberglass substrate. Unless you give your boat a long period in the hot sun to totally dry, I think you might end up hatching more blisters with the barrier coat (see my experience, read on). I agree with your general approach, but I would not put a barrier coat over gelcoat that has already shown a penchant for bubbling. I pointed out earlier in this thread, I bought a boat that had had a bottom job where a very expensive yard had put a barrier coat over some damp gelcoat and hatched 10,000 blisters. I peeled all the gelcoat off the bottom (Swan and Nautor never put gelcoat on the bottom in the first place because it actually serves no purpose other than to make a cheap smooth surface to paint. I have some blisters on my current Ericson that I will look at when I haul, but unless I think they are attacking the glass beneath (something I have not seen in the yards I have been in), I will likely do nothing.
 

PANorth

Member II
unless I think they are attacking the glass beneath (something I have not seen in the yards I have been in), I will likely do nothing.
How will you know unless you dig into the blister? We had blisters that had multiple layers of delamination of the fiberglass. We kept going until we hit fiberglass that looked and sounded (tapped) solid. Even then, as described in one of the threads linked above, moisture bubbled up in a few spots when we heated it to apply the first epoxy.
 

Pete the Cat

Member III
How will you know unless you dig into the blister? We had blisters that had multiple layers of delamination of the fiberglass. We kept going until we hit fiberglass that looked and sounded (tapped) solid. Even then, as described in one of the threads linked above, moisture bubbled up in a few spots when we heated it to apply the first epoxy.
What I thought I saw were many small blisters. I would probably open ones that were larger that a quarter or 50 cent piece. If you had multiple layers of laminate affected on even one of them I would be concerned about the integrity of the layup. I think blisters are more of a symptom than a cause of delamination. But that is just an opinion. The blister problems in the 80s (Valiant, Uniflite) were about a fire retardant mixed in the resin. I believe this started lots of folks believing the gelcoat blisters were an indication of some similar laminate problem in other production boats. I think most boatyards have cooled their blister frenzy. But that is not to say delamination could not happen. Some of the Ericsons were said to oil can and that flexing could cause delamination. As could a resin starved layup that gets worked a bit. I have not seen any boats sink from blisters or localized delamination. Having been a victim of over reaction to the blister crazes of the 80s, I am probably on the other end of the spectrum these days.
 

Prairie Schooner

Jeff & Donna, E35-3 purchased 7/21
I would suggest caution with the idea of a barrier coat unless you are going to strip all the gelcoat off and recover with glass. The problem is that your moisture (and this is true of most blisters I have seen) are between the gelcoat and the fiberglass substrate. Unless you give your boat a long period in the hot sun to totally dry, I think you might end up hatching more blisters with the barrier coat (see my experience, read on). I agree with your general approach, but I would not put a barrier coat over gelcoat that has already shown a penchant for bubbling. I pointed out earlier in this thread, I bought a boat that had had a bottom job where a very expensive yard had put a barrier coat over some damp gelcoat and hatched 10,000 blisters. I peeled all the gelcoat off the bottom (Swan and Nautor never put gelcoat on the bottom in the first place because it actually serves no purpose other than to make a cheap smooth surface to paint. I have some blisters on my current Ericson that I will look at when I haul, but unless I think they are attacking the glass beneath (something I have not seen in the yards I have been in), I will likely do nothing.
Thanks Ray. It's really appealing to be able to cut out the expense and time of barrier coat. I'd just assumed it was standard procedure. I might call Total Boat and see what they say, fully aware they have a vested interest in selling the stuff. It's complicated by an unusually wet spring here, tho the boat has been out of the water since September. I'm continuing to watch responses here before we decide.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Thanks Ray. It's really appealing to be able to cut out the expense and time of barrier coat. I'd just assumed it was standard procedure. I might call Total Boat and see what they say, fully aware they have a vested interest in selling the stuff. It's complicated by an unusually wet spring here, tho the boat has been out of the water since September. I'm continuing to watch responses here before we decide.
If you decide to apply a barrier coat, it might be helpful to put a tarp around the hull (taped in place to minimize air escaping) and add an industrial heater for a few days to further dry out the hull. You should be able to rent one at an equipment rental shop.
Frank
 
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