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

Slick470

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.
 

PANorth

Member II
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.
 

markvone

Sustaining Member
Phil,

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.

Mark
 

Tombee

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.
 

PANorth

Member II
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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jtsai

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.
Frank
 

PANorth

Member II
The spring highschool sailing season is over. Time to get back to working on the big boat.
I discovered that the problem is with the meter. Or that it is not the right meter for the job. The fiberglass thickness on the hull may not be thick enough. The meter reads at 3/4" depth in the material. I don't think the hull is that thick - is it? We put the meter on the metal of the stand and a brick. It maxed out there too. One mystery remains - the meter seems to read on the topsides, which I doubt are thicker than the hull. I think we will go with the plastic wrap method, which is showing that the hull is dry. I guess it's time to start glassing.
Meter on topsides.jpgMeter on plastic.jpegMeter on stand.jpg
 

Pete the Cat

Member III
I put moisture meters in the class of those bent wires some folks use to find septic tanks and underground water sources. I guess some folks have found them useful but they seem to measure conductivity not actual moisture--and conductivity can be influenced by bottom paints, resins and laminates used in the layup. I redid the bottom of my Tartan many years ago and will spare you the details--suffice it to say that even after peeling and laying down the new glass, it measured about the same as the old.
 

jtsai

Member III
I agree with Pete about the moisture meter. It measures conductivity between probes or across a sensor plate; it is more suitable for comparing areas with similar substrate compositions. R.C. has a technical article about Electrophysic moisture meter (https://www.pbase.com/mainecruising/moisture_meter) which I purchased one decade ago and have used it when boat shopping. It is an excellent tool for picking up wet deck.

I am puzzled by the success of your "plastic wrap" method. You did not introduce vacuum in the system to lower the moisture boiling point, just a dehumidifier in the cabin? Isn't the only difference between wrapped and unwrapped areas is rain protection?
 
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PANorth

Member II
An update:
We have now had the boat under the shelter on the hard for a year. That's a bit of a disappointment. I was really hoping to do some sailing while the weather was still warm. Now I am hoping for some winter sailing, but I am not keeping my fingers crossed. If I can get it done before the highschool sailing season starts again in the spring (last fall regatta is this weekend) then I may get back in the water before summer.

I have done two layers of fairing. The first was with thickened West System. The second was System 3. It wasn't premixed but was a lot easier to use than West System. I am in the process of sanding, but it's clear that I will need at least another layer of fairing. I plan to proceed with System 3. So far I have used plastic blades made for drywall mud. I use blades that are big enough (4" to 12") to bend them to the curve of the hull and extend beyond the edges of the divot that is being filled. Nearly all still have minute depressions. Does anyone have suggestions on a method for filling these effectively? In reading back through the posts I see where others mentioned multiple layers of fairing. Thanks, now I am emotionally ready for that.

A note on the pink layer discussed above - A friend said that he had heard about racers in the 70s and 80s putting a very smooth, gelcoat like layer on their boat instead of bottom paint. The layer has no ability to stop growth. Growth was prevented by parking the boat in a plastic "bathtub" in the slip and pouring bleach into the sea water around the boat. This was in the early days of the Clean Water Act so standards were not what they are. My friend thought that this might be the pink layer on my boat. This boat was raced in the Pacific. Has anyone ever heard of that?

We did an adhesion test using Gorilla Tape. We stuck it to various surfaces, including the bottom paint still in place. Anything that came off on the tape needs to be sanded off completely before the barrier coat goes on. The pink layer showed a very faint residue on the tape, then none if I scrubbed it with a paper towel. I am not planning to remove the pink layer.
 

Saverio

Member III
Hello, from the photos, the boat has no major problems, the osmosis is repaired. Put the boat in a ventilated place, open and smooth all the bubbles, let them drip, wash the boat with fresh water, test with humidity hygrometer, then when dry you have to sandblast the whole boat, we rent equipment, wash it fresh water, clean with nitro diluent the whole boat, now fill fiberglass in all bubbles, smooth and fill until it becomes even and shiny, check humidity, if all goes well, pass two-component liquid anti-water primer, let it dry, check humidity, if fine, primer and antifouling. This is my experience made by me on the advice of the shipyard made in 2003 on my former sailboat Elan 333 of 10 meters, You can restore it too. Hello. Xavier
 

Saverio

Member III
The new owner, who I had advised of all the work done, told me that the humidity is under control, the boat is doing very well.
 

Saverio

Member III
my total expense including parking area in the construction site for 6 months and material, € 3,500. If the work did the construction site € 5,000.
 

PANorth

Member II
Thanks Xavier. It seems like persistence is the key ingredient for DIY. I am hoping that another layer or two of fairing will get us to a smooth enough hull. My boat partner and I are having discussions about what is smooth enough. I think a little more of my ego is in how the bottom looks. So the balance between my ego and my patience may the the final factor.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
One 'rule of thumb' is that you need cloth to layer-in where you ground out cloth or roving. i.e. you are restoring hull laminate strength. The fairing part just has to adhere very well, as it is not structural.
 

PANorth

Member II
We glassed all the deeper blisters where we had ground beyond the chop layer. Some of those covered a relatively big area. We finished that part a while ago. Now it about how to get the final layers of fairing on most efficiently and deciding how much fairing is enough. I don't think we are there yet.
 

Pete the Cat

Member III
i am not sure what equipment and process you using to fair the hull--or of what specific issues you are encountering with your current approach, but--in my experience--technique and equipment matters. A dual action sander (larger is better, but increased weight comes with size) with the capability of vacuuming aggressively through the paper is required so that you can keep going. Personal protection is really really important--the guys who so this professionally use positive pressure suits because the dust is really awful. And you have to keep the DA moving widely over the surface--technique matters. It is exhausting overhead work that I could not do at 75 anymore. I recall that when we faired the bottom of my Tartan 37 the we had about 80 hours in the effort using West System. I liked System 3 but the shelf life of the stuff was so poor (is it still?) that we stopped using it at the yard where I worked--makes a gooey mess if it gets past its useful time. Just thoughts about the process. My experience was 25 years ago and things might have changed. The bottom of my Tartan still looks perfect.
 
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