Rule of thumb for cloth, thickened epoxy or just fairing in abundant blister repairs?


Member III
We ended up peeling the bottom of ours and putting glass back to fix the blister issues on our boat. From doing lots and lots of research before tackling ours, I found that there is no real consensus on what the right way to fix the problem is but there was no evidence that osmosis has ever caused a structural failure on a solid layup fiberglass boat. However, it is ugly, slow, and can obviously affect resale.

Looking at your pictures and comparing them to mine, my guess is the red layer is years of hard bottom paint buildup. The red paints have a habit of fading to a pinkish color as the copper leaches out. The white layer is gelcoat, and I think I see a thin grey layer under the white which I also found on our boat which is another layer of gelcoat between the white gelcoat and first layers of fiberglass.

I initially just wanted the bottom peeled to remove the paint and gelcoat layers, but after seeing the results of that first pass, the peeler and I agreed to take it down another 1/16" or so into the fiberglass to remove the worst of the blisters. I then spent the remainder of the summer grinding out deeper spots that became visible as the boat dried. Most of which were in the first foot or so below the waterline.

I worked out a deal with the peeler where I did all the sanding/grinding, and he checked on the moisture content every few weeks and then when the boat was dry enough, he did a few rounds of fairing, with me sanding in between, and then he put on layers of fiberglass cloth with vinylester resin to build back up the laminate and seal in the repair. After a few more rounds of fairing and sanding, I put on epoxy barrier coat in alternating colors, and then my bottom paint of choice.

Next time, (if there is a next time) I think I'll just pay the guy to do all of it.


Member I
I'm one of those people with more time than money. So, I'm not likely to pay someone else to do the work. As you would hope we got a pretty good deal on this boat. Though that was based on a survey that guessed a much better bottom than it turned out to be. I am more and more convinced that surveyors do a lot of guessing, with maybe less real insight than we all assume when we pay them. If I ever buy another boat, I will do much more due diligence, by looking at forums such as this. I would still have bought this boat, but maybe offered a bit less.

I don't think you see a grey layer. After spending many hours sanding, grinding and looking at this bottom, it is red, white, red then fiberglass. Last fall when we had just started to explore the blisters we asked for advice similar to this thread. That discussion included some knowledge about the Ericson manufacture process. As in one of the posts above, some thought that Ericson used a red material as an outer layer. Because of the hardness and smoothness of the outer red layer and that there are no flaws (except at the blisters), I am inclined to go with the manufacture theories. The darker material, we have not completely removed on top of the pink/red, is probably residue of bottom paint.

Peeling may have been the way to go on this boat. We would have had to do as you did, Slick: peel then grind the deeper spots. The peel would have had to remove the the chop layer to be effective. Now I think we are far enough into blister removal to keep going as we are. There is certainly lots of fairing in our future.

There is judgement in deciding which spots to grind. Most of the blemishes on the surface are blisters, but some are not. Yesterday, after working an area of fairly high density blisters where a stand had been (we move the stands yesterday to work those areas), I decided to open up a blemish that I normally would have judged to be nothing. It turned out to be the deepest blister yet with a large water filled void. A retrospective hint was that water was seeping out of the hull from adjacent to the stand where there was no sign of a blister. Obviously the weight of the boat on the stand flattened the blister and squeezed some water out of the void.

I appreciate all this feel back. Please keep it coming. I'm learning lots.


Sustaining Member

Here is another E36RH owner who had his hull peeled and did the re-glass blister repair himself:

Note: The peel was in April 2012 and the repairs finished in Oct 2016! Robert had free storage/work area on the hard.

For reference, there is a very experienced local (Chesapeake Bay, MD) company, Osprey Composites that I believe is under $300/linear foot for blister repair:

I would have to seriously consider the total cost vs loss of use time span for this type of job.

I've also read about another Ericson owner who had a total blister job fail and it had to be re-done, so experience and warranty are important.



Member I
For what it’s worth here’s my past blister experience on my E38. First haul out several years ago showed many blisters and I trust my yard guys so I let them determine whether to fill, grind, fiberglass, etc. After those repairs we applied a good barrier coat and bottom paint. My next haul out about three years later showed six blisters and only one needed fiberglassing. The previous owner was not applying a barrier coat and I think it made a difference.


Member I
OK, a new question in this process of fixing abundant blisters: My plan was to let the boat sit and dry while I worked on other things. I was thinking that I'd get back to the hull later in the summer. Our weather around the Salish Sea (aka Puget Sound) has been cooler than normal and rainy until about the last week. We can expect rain well into June (locally June-uary). I placed a heater and dehumidifier inside the boat during the winter. I also taped plastic wrap to several places around the hull to monitor the drying process. I have been surprised to find the plastic completely dry. Is there some unaccounted for physics at work here? Could the heater and dehumidifier be drawing the moisture into the boat? In contrast to the plastic - the moisture meter is showing 8 to 13% moisture on the topsides and immediately jumps to 99% when I cross the waterline. Everywhere below the waterline the meter reads 99%. I understand that moisture meters are relative readings and this is a relatively big difference.
Any ideas about what is going on here?


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Member III
the moisture meter is showing 8 to 13% moisture on the topsides and immediately jumps to 99% when I cross the waterline. Everywhere below the waterline the meter reads 99%. I understand that moisture meters are relative readings and this is a relatively big difference.
Any ideas about what is going on here
I have placed moisture meter on areas with known wet core but have never seen a 99% moisture meter reading. Is it possible the meter is reading rain water trapped between layers of old anti-fouling paint? Very strange.

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Yes, this is all very puzzling, and perhaps complicated by the cold, wet weather in the Pacific Northwest this spring. With the current cloudy, rainy, high humidity weather, I'm not sure I would trust a moisture meter reading now. I would try it again after a few warm, sunny days to see if you still get 99% reading. Keep us posted with your findings.