• Untitled Document

    Join us on March 29rd, 7pm EST

    for the CBEC Virtual Meeting

    All EYO members and followers are welcome to join the fun and get to know the guest speaker!

    See the link below for login credentials and join us!

    March Meeting Info

    (dismiss this notice by hitting 'X', upper right)

Hull Blistering Under Epoxy

footrope

Contributing Partner
Blogs Author
A surprise awaited us a month ago when we hauled the boat after three years in the water. A whole bunch of small blisters were on the hull below the waterline. More appeared as the days passed and even as the light changed while I worked on sanding and "picking" at them to get to epoxy that would stick to the hull. These all started smaller than the diameter of a pencil, many of them much smaller. A little water was present in probably 85% of them, and we could often detect the faint vinegar odor of "spoiled" fiberglass resin.

I may be approaching 'boat pox' with this many blisters, but right this minute I am unwilling to spend the cash to have the epoxy bottom removed and a new one applied - I'll have to pay the pros to do this. The WEST System epoxy job is about 13 years old and is thin in some spots. My thinking is to do a good, and hopefully permanent, repair on these areas using a newer epoxy, and then see what the next haulout shows in a couple years. Meanwhile we'll save for a winter haulout and completely redo the bottom, in case we have a relapse.

The pictures attached show some of them, especially some of the clusters. The moisture meter readings were donated by the yard and were completed when I was about 75% done sanding. I was not present to observe the meter readings. Areas above 7% moisture were marked. The range is 8 to 17%.

I have been doing some reading about blister repairs, and more importantly, trying to determine whether to grind, and how deep and wide to grind when that is indicated. I seldom bring a problem to the board without some thinking being done by reading past threads, and without some plan for you to poke holes in.

  • I've completed the initial sanding around each, the results are as you see in the pics. There are some that show white glass fibers at the surface.
  • I have sounded most of the areas of the hull with the back of a screwdriver handle and found that almost all of these areas have no change in sound across them, at least not to my ear. I will re-do this as I prepare to address each one. I am encouraged by this, but ...
  • Those areas with a perceptible sound change will be investigated by some exploratory grinding. Exploratory grinding into layup will of course result in repairs with glass cloth and epoxy. 12:1 and 20:1 are mentioned as grinding diameters if I have to go deep.
  • I have purchased Interlux 2000E epoxy for the repair. I've used this in the past for recoating the bottom in several small areas the last time we were out of the water for paint.

Questions:
1. How can I tell where I should be grinding? Is sounding sufficient? Should moisture readings be a major guide and what is a bad moisture reading? I have heard moisture readings done badly can be misleading.

2. When I do grind, how can I tell that I am deep and wide enough? One method I read involves hardness readings and additional moisture measurements as you go. Individually these don't seem too bad, but the clusters bother me.

3. Is the 2000E epoxy among the best for the epoxy or should I go back to WEST System with colloidal silica thickener?

Thanks in advance for your reactions and recommendations.
 

Attachments

  • HullBlistersPopped01.jpg
    HullBlistersPopped01.jpg
    191.4 KB · Views: 89
  • HullBlisters01.jpg
    HullBlisters01.jpg
    179 KB · Views: 90
  • HullBlisters02.jpg
    HullBlisters02.jpg
    201.6 KB · Views: 85
  • HullBlisters03.jpg
    HullBlisters03.jpg
    166 KB · Views: 83

Emerald

Moderator
What timing. I'm sitting here after spending the day doing what you are getting ready to do. I'm going to start this by saying that I think there are more opinions and experts on blisters than there are on bedding compound :rolleyes: What I am going to recommend will be completely blasted by some. You will be told to peel your hull, put it inside for a year, and a variety of extreme measures. I'm sure you've seen a ton of the information out there. I finally decided to do a hybrid approach based on the input of some people I trust who have been running a yard for many years and are experienced dealing with this type of stuff. The approach is to grind out the individual blisters and fill with West Epoxy thickened with 406 basically following the procedures as described on West's website here:

http://www.westsystem.com/ewmag/17/repairinggelcoat.html

and then putting two coats of the Interprotect 2000 on over the above. In the course of this, we have decided to disregard the moisture meter for a variety of reasons. Here's one angle on it:

http://www.yachtsurvey.com/my_wet_hull.htm


I ground out only the visible blisters. Used an angle grinder. Only ground deep enough to remove the damaged material and get to dry glass. Almost all of these were small and very shallow. Part of the consensus I've come across is that your hull starts absorbing water as soon as launched, and within probably the first 5 years of your boats life, you are wet and will or will not blister based on this. I will be looking each year at haul out for any new blisters and will repair as I deem necessary.

Hope this helps. It's good to think I'll be back in the water soon, not stuck in a shed for a year waiting to be "dry" :cool:
 

u079721

Contributing Partner
I don't have any sage advice about blisters, except to say that they can be impossible to fix. Our 1989 E-38 hull blistered with thousands of tiny eraser head sized bumps just after we bought it - in spite of a survey showing no problems with a moisture meter (so much for that concept). We paid to have it peeled professionally, and coated with six coats of West System. Looked great (~$5000 IIRC). Next haul out - blisters are back. So they honored their work, and pealed it a second time, and recoated a second time. Next haul out, a few blisters are back, which they spot fixed. And fixed. And fixed. Every single damn year we hauled the boat we found more. In our case the new blisters were between the hull and the epoxy, and in no way affected the lay up, they just looked bad. The yard and I even had the folks from down the street at West Systems come take a look, with no real suggestions other than taking a hull core for analysis, which I was reluctant to do, since it wasn't really a structural issue.

When I had to sell our boat in the fall of 2004 I dreaded the inspection, because sure enough there were blisters everywhere. I only closed the sale by agreeing to give the buyer back $5000 for blister repair after closing.

I still don't know why our blisters would not stay fixed - or rather, having peeled off the gel coat, why the layers of West System epoxy would not stick to the hull. But the whole issue sure detracted from an otherwise wonderful experience owning and sailing my Ericson.
 
Last edited:

rwthomas1

Sustaining Partner
I know two reputable fiberglass guys and they both do the same thing: Grind out blisters with dremel, angle grinder, etc. Sand entire hull to gelcoat or to barrier coat if spot repairing. Wash entire hull. Let hull dry over winter. Fill with Interlux or West, sand and barrier coat. Thats it. The full peel job is reserved for the worst cases. Thankfully my boat had been barrier coated in the past and no blisters were present when I hauled after two years. Fingers are crossed. Good luck with it. RT
 

EGregerson

Member III
blisters

Ditto to what RT says; I've had 2 surveyors say a dry hull is the key. My hundred little blister bumps were from the PO epoxying over a wet hull. They say, let it sit out over the winter. One suggested taping a plastic drop cloth to the hull; sort of a skirt to keep rain from running down under the hull. Epoxy in the spring. I have guarded optimism as to what I'll see this fall when I haul out.
 

jkenan

Member III
I went to the extreme, and peeled my hull based on the many blisters I had, the many layers of bottom paint from the PO, and the yard recommendation. In some ways I wished I hadn't, because, it revealed an even greater degree of osmosis than I had anticipated based on the blisters evident at haul-out. What I learned was that a PO had attempted a bottom job on this boat, and had sealed in blisters with the barrier coat without repairing them, exacerbating the problem, and now I have a real job on my hands.

At the same time, I'm also helping a friend of mine with his Cal 24 that stayed in the water year round for years and years with a short-haul every year for a pressure wash and new bottom paint. He knew he had blisters so I offered to help. Peeled his too. The extent of his osmosis was frightening. Even after peeling, we ground out many waffle-sized areas of delamination that were still wet after months on the hard, that came very close to breaching the hull! So now we're in the process of reinforcing those areas with cloth, and then filling the hundreds of other ground out blisters with cabosil, then finishing the bottom job.

Peeling is extreme, and not warranted in every instance. If you know you've got a serious issue, it may be the way to go. The benefits are that you personally don't have to deal with the the toxic exposure of removing bottom paint, and afterwards you have a better understanding of the extent of your situation you may not have had before. At any level, if you have a void in your laminate, even if allowed to dry out, it will continue to absorb and get worse over time unless repaired.
 

Jarod

Member III
I second Emerald's response after already going through this myself on my E27. I had well over 200 blisters on my 27 i sanded the old paint off right down to the gelcoat and individually ground out each blister with a dremel most were just slightly into the chopped strand outer layer. I recall one or two that actually went into the layup a bit. I filled everything with west system and coloidal silica then sanded fair. I followed with two coats of interlux and called it a day. This was over two yrs ago I hauled one year later and no blisters and on this last haul two yrs later i found one small blister. I think your repair will have the same shot as the $10,000 repair the yard will quote you. I would do the best you can with it and not sweat it too much. The whole thing has been blown way out of proportion in my opinion...is it unsettling when it happens to your boat....sure, but I wouldn't peel it going from the pics you have posted
 

Emerald

Moderator
In addition to all the other good feedback, I would add I've come to the conclusion that part of what is important is just staying on top of this. Grind out and repair the little gelcoat blisters as they appear and don't ever let them turn into a big blister impacting the laminate.

In the West Systems article (http://www.westsystem.com/ewmag/17/repairinggelcoat.html ) they talk about boat ventilation on the inside, and low and behold, the worst blisters in Emerald are in the area of the hull forward starboard which has minimal ventilation due to the way the V-berths and lockers are constructed. The original and prior owner of Emerald bore large holes in all the locker doors and drawers to give ventilation. He saw it on some boat at a boat show and came back and did this. Well, he may have helped her. In most all of the areas with good ventilation to the interior, the blister rate was minimal. It was in this one forward area where there weren't any particular doors to drill his holes in where the blisters were the worst. Kinda makes one wonder if we should not be painting the inside of our layup and running dehumidifiers of some sort when possible off the shore power. Makes me wonder if moisture moves through the laminate, is it possible to do some drying via the interior of the boat? Anyone else notice a correlation between blister location and interior ventilation?
 

jkenan

Member III
Great article, Capt. Dan. Based on this article, had I read it before buying my E29, I might have passed on buying it since it had a previous blister repair that was in the process of failing. See the photo below of what the first few swipes the planer revealed in my starboard bow when I had my hull peeled - the reddish coat was a previous barrier coat over the gel coat, and you can see how many blisters existed underneath that were still wet, and the rest of the hull is the same. My friend's boat, the Cal 24, is much worse-off than mine, as you can see in the photos (the ones with the reddish hull - these were taken after the peel job which went deeper into his hull than mine, and it still didn't reach some of largest blisters, which you can see hiding in deeper in the laminate) . After grinding away at his blisters, all I can see is mat, which is consistent with the article's analysis of why thickness built out of mat is a primary cause of the problem. I have already ground out the thru-hulls for the scuppers on my E29 since I'm moving them to above the water line, and immediately found cloth and roving. I haven't started grinding away at my blisters yet, but expect I will find the same, which is encouraging, and a testament to the quality of the Ericson line (and the reason why they should be cared for!).

Does anyone draw a distinction between peeling and planing a hull? Mine was done with a hand planer & carbide blades (as mentioned in the article), and removed the gel coat and 1st layer of mat (there is still plenty of hull thickness). Total job cost me $750. Of course, I'm doing the rest, which will include grinding out all voids and filling as recommended, coating, etc.

In the end, it is an individual choice how to proceed with these types of issues. The best you can do is read, read, read, and understand all the alternatives as much as possible and consider them in the context of your own situation. I think I did the right thing by removing the existing barrier coat, gel coat, and 1st layer of mat, since keeping the old barrier coat on would continue to trap moisture making the problem worse, and now all blisters are clearly revealed, will be repaired, and the hull is drying out (currently about 10%). After reading this article however, I will re-think whether I will apply any barrier at all, or just fix the blisters I have, and continue to do that at every haul out. Again, learn as many options and opinions as possible, and draw your own conclusions from a knowledgeable perspective. Could what I'm doing be a mistake? Sure. But it sure beats not caring about it all. It is interesting and fun, and I can take this experience with me through my boating life, having applied myself to the task in full, and not half-assed.
 

Attachments

  • Hull1.jpg
    Hull1.jpg
    100.9 KB · Views: 89
  • DSC_0137.jpg
    DSC_0137.jpg
    70 KB · Views: 92
  • DSC_0130.jpg
    DSC_0130.jpg
    77.3 KB · Views: 90
  • Cal24.jpg
    Cal24.jpg
    65.4 KB · Views: 92

footrope

Contributing Partner
Blogs Author
Thanks for the support and info

And good luck on the ongoing repairs and suspenseful waiting.

Based on appearance and sounding, I think I am largely dealing with the chopped strand layer, and maybe the first layer of cloth on just a few. When the boat was layed up by the PO, he had it in his backyard in Arizona for over 3 years. That and the Ericson pedigree make me think this is a sound hull, a decent epoxy job, and after all this time there is some water getting through the bottom paint and epoxy, not migration through from the inside. I will check under the v-berth at the bow. Water had collected at that point in a poorly drained area and I have some blistering up in that area of the bow. The water migrated there because the anchor well had filled with rain water and overflowed through the hawse pipe while the boat was at the broker.

The boat was used by the PO in the summer of 2002 and then sat at a broker's dock until we bought it in June 2003. The survey haulout was fine. In 2005 I found four areas where the epoxy had chipped, sanded them out to where adhesion was good, and repaired with Inteprotect 2000 - about three layers. Those areas aren't affected except at the edges of two of them. I also sanded the hull gently to get the paint crumbs off (not really listening to the yard when they asked "Why?"). The yard this year also said they don't sand a good paint job, just pressure wash, dry for a couple days, repaint. I may have hurt the water barrier doing the sanding back in 2005. There was only one or two coats of paint on the hull in 2005, so I am not dealing with a build-up there.

My take away is that I can repair these areas without going deep into the hull. Once they are repaired properly, few of these areas will be a problem in the near future. If more are evident in 2 or 3 years, and they are small and shallow like these, same repair method applies. Eventually, perhaps the entire hull will be a mass of small repairs all run together and fewer blisters will show up - certainly no structural ones.

For the severe damage cases, it's clear what must be done. What jkenan and his friend are dealing with is very different than my case and it seems like they're doing it right.
 

CaptDan

Member III
blastin' blisters

Great article, Capt. Dan. Based on this article, had I read it before buying my E29, I might have passed on buying it since it had a previous blister repair that was in the process of failing...But it sure beats not caring about it all. It is interesting and fun, and I can take this experience with me through my boating life, having applied myself to the task in full, and not half-assed.

It's a very controversial issue. On the one hand, a caring owner wouldn't neglect to deal with blisters; on the other, how far do you go? I think it gets down to determining what constitutes a major problem, and what's really a chronic small-scale headache.

As Craig says, Ericson's reputation of solid build quality tends to mitigate issues owners of other brands SHOULD be worried about. So I think he's going about it the right way, as I think you did as well.

However, what pisses me off NO end are the scare tactics metted out by cash hungry boat yards who'll sell a full on bottom job at high cost with questionable long term results. Putting it in medical terms, a hang nail doesn't present the same threat as a heart attack.

Nonetheless, a well done bottom job, with little impact to laminate integrity might be the best option in many circumstances.

YMMV.

Capt Dan G>E35II "Kunu"
 

Greg Ross

Not the newest member
Bottom Job

I started stripping I believe, what constitutes 27 years of bottom paint. With commitments away from the boats home locale I`m only going to manage completing half the hull this season before launch.
I was rather intrigued with what I uncovered as I went along. PO who`d owned the boat from approximately 1990 until 3 years ago likely had done some poorly executed blister repairs. The one side of the hull revealed about 10 spots that had been reamed out and poorly filled and then slathered over with a small area of epoxy. I did grind out several of them and found no wetness and the ones i`ve just faired with my sander did appear to be sound.
Once many, many layers of anti-fouling were chemically removed I came down to what appears to be a``red lead`` coat. Beneath that is a green tinted thick layer, I`ll say it looks like body fill fairing! As I sand that layer I am exposing tiny white, presumably gelcoat protrusions in that filler. Further sanding has not revealed any pores or voids. Size wise, I would say they`re 10% of the size of a pencil eraser and there are lots of them.
David, I would on the basis of your comments have to go back and study their density relative to where the bulkheads and void spaces are located.
There were also copious amounts of some other filler product used around the rudder gudgeon and propellor strut. Found all sound material where I had done some extensive grinding at the centerline protrusion in way of the Prop. This was necessary to add clearance for a 14 inch diameter prop going on this Spring (associated with installation of a 3HM 35 with a 2 : 1 gear)
Thus far I have not seen anything that alarmed me. My current plan is to complete sanding of the one half of the hull and apply several coats of epoxy as the barrier coat. The boat is typically hauled for the Winter, and covered and I do keep a tickle of heat on in the boat to lower the interior humidity level.
That`s my strategy. And next Fall I will carry on with stripping the other half of the hull.
 

Emerald

Moderator
Once many, many layers of anti-fouling were chemically removed I came down to what appears to be a``red lead`` coat. Beneath that is a green tinted thick layer, I`ll say it looks like body fill fairing! As I sand that layer I am exposing tiny white, presumably gelcoat protrusions in that filler. Further sanding has not revealed any pores or voids. Size wise, I would say they`re 10% of the size of a pencil eraser and there are lots of them.
David, I would on the basis of your comments have to go back and study their density relative to where the bulkheads and void spaces are located.
There were also copious amounts of some other filler product used around the rudder gudgeon and propellor strut. Found all sound material where I had done some extensive grinding at the centerline protrusion in way of the Prop.

This is interesting, as I too have hit this red layer and then the green tinted layer. I had thought the green tint was tied to my hull being green - that I was just seeing gelcoat. Perhaps not. I also have found what sounds to be very similar filler in the rear quarters as you get some compound curves coming in to, yes, the area with the propeller shaft, and gudgeon for the rudder. I've looked at this with folks at the yard, amongst others, and we are thinking that some sort of filler might have been used in these areas due to their complex shape after the pieces were pulled from the mold. I will note that it (possible filler) all seems the same. The green tint is completely uniform in all areas. Everything seems to be sound and original. Time for a dark and stormy.
 
Last edited:
Top