Trouble! "Blisters" on the underside of my canoe

doe4rae · Post by **doe4rae** » Mon Jun 21, 2010 9:44 am

Hi folks.... I have two small blisters --- (delamination?) on the underside of my canoe. There are in close proximity to one another. One is about 3/4" round and the other is about 2 1/4" long by 1" wide. They appeared this last weekend after I had the canoe out on the water for a little over an hour. This is my fourth time out and I know they weren't there before. (As much time as I spend wiping down and staring at my boat it would be impossible to miss them.) Anyway, when we flipped it over to put it on top of the car I saw them immediately. It doesn't seem like there is any water under them. I think I know what I have to do to repair it but there are two real concerns on my mind. Why did it happen and is this "only the beginning" ?
As you will be able to see from the picture, it seems to have occurred over a piece of cedar that is darker - heartwood? - and probably soaked up more epoxy, starving the cloth and therefore not making a good bond to the wood. Still... with 3 more layers of epoxy (4 total) and 4 coats of varnish, this still seems like an impossibility? I haven't cut into the pockets yet. I have a couple of questions about that. Is it possible to just cut a slit in this blister and fill it with epoxy and press it back in place? (Sand, re-varnish) Or do I have to cut it out completely and patch with new glass?
One more question... I was hoping to take this canoe for an extended (like 3 day) camping trip in Voyagers. Really been wanting to do that all spring. But this has me worried that a full day on the water would result in me pulling in to camp in the evening to flip my canoe over and find the entire hull bottom covered with air pockets, looking like a leper! What would a person do if they were in the wilderness with another day or so of canoing to do and you found this damage? Is there a way to do a quick "patch" or fix so that you can keep going? How bad is it if you break through the glass and the wood gets wet? Even thinking about fixing this spot has me frustrated with the possiblity of not being able to use the boat for another several weeks as I wait for epoxy to cure and varnish to dry. Again. GRRRR.....
All your thoughts and experience -- as always -- are so much appreciated!
Here is a link to the picture (sorry I still don't know how to post pictures on here.)

http://picasaweb.google.com/olson.dawne ... 8989696722

Dawne

Rod Tait · Post by **Rod Tait** » Mon Jun 21, 2010 3:54 pm

If the spots had appeared quickly and as you state in your photo description, it was quite hot out, I would suggest that the blistering is due to moisture either from plain water or uncured epoxy that has expanded in the heat. It definitely looks like the glass is lifted from the wood, which would indicate a problem in first coat of epoxy, not subsequent. You will need to break it open, and if anything is sticky, then it is uncured epoxy (poor ratio mix or not mixed enough). If the trip is planned, better to find out now than to have the bubble expand in hot conditions. If it is a bad mix of epoxy, it may be in other areas and get larger. If it is dry underneath, then a quick patch of epoxy/glass will get you on the water and you can make it pretty later.

doe4rae · Post by **doe4rae** » Mon Jun 21, 2010 4:13 pm

It doesn't "look" wet underneath -- but I will check. If it is dry, do you think I need to cut out all of the area that is lifted off the surface? Or can I make a slit, and put some fresh epoxy inside and then press it back down into place?

I kind of think that the cedar strip pictured was much more porous than the other strips around it and soaked up more of the epoxy and this (possibly) could account for poor adhesion of the cloth on this one strip? I am really really hoping that is it, because I was so careful about the mixing of the epoxy! However it was a little cooler (58- 60 F) the day I did this.

I am certainly going to be a lot more particular about removing areas of the planks where there is a lot darker wood or close to knots. These areas showed up so much darker after glassing than they did as bare wood.

doe4rae · Post by **doe4rae** » Mon Jun 21, 2010 5:29 pm

Maybe I'm just looking for an easy way out here... or hoping to not hear the worst. However, I cut into the bubbles and the part that I cut away is so thin.. I wonder if it is only the varnish coats that bubbled for some reason? I just think that varnish plus epoxy would be much thicker? Its weird. I am adding another picture. Also - dang it - it is mildly sticky under that bubble. The pieces I cut away (the actual bubble under surface are quite sticky but the cloth seems stuck tight to the hull and not near as sticky. Granted I didn't try very hard to get under the cloth to the wood because I didn't want to create more damage than necessary.

I'm pretty perplexed. :confused

http://picasaweb.google.com/olson.dawne ... 2955910434

Glen Smith · Post by **Glen Smith** » Mon Jun 21, 2010 6:22 pm

I would hate to "burst your bubble" but I recommend cutting out those areas going 1" beyond the edge. Clean the areas with acetone or lacqueur thinner. Lightly sand then apply a glass patch following the standard glassing procedure. Varnish when ready.

willo · Post by **willo** » Mon Jun 21, 2010 8:23 pm

I think what Glen says is good advice , and maybe Rod will have more for you . This could be patched up quick enough for your trip. You could leave the varnish for later. You will be surprised at how well a patch will blend. I have done two to repair damage and I can no longer find them.

Post by **Patricks Dad** » Mon Jun 21, 2010 8:26 pm

If the piece that you have removed indeed includes the glass, then patching as Glen suggests makes sense. But from your last post it suggest that the glass might still be intact. You should be able to flex the piece of material you have removed to determine if it includes the glass or not... If it is simply epoxy and varnish, you should be able to sand down a bit around the area and add a couple coats of epoxy and then varnish without adding any new / additional glass. This would make a big difference in the complexity of the repair.

BearLeeAlive · Post by **BearLeeAlive** » Mon Jun 21, 2010 10:32 pm

I am no expert yet, still a learner, but my thoughts were just what Randy said. It really looks like the glass is still in place on the hull, and the subsequent layer of epoxy never bonded.

Rod Tait · Post by **Rod Tait** » Mon Jun 21, 2010 10:44 pm

The last picture you posted definitely looks like you have cut away the fiberglass. And yes, saturated with epoxy, the glass is quite thin. There will still be epoxy saturated into the wood, so it could be decieving. But if there is tackiness under that glass, then epoxy has not cured and after all this time, unfortunalty it is unlikey it ever will. Take some lacquer thinner and try to wipe off the uncured epoxy and then patch and go paddling. But if more bubbles show up especially under heat, then your problem is bigger than the one or two small spots. I would add that if the epoxy was on top of the glass and it had not cured, it would not likely bubble but just be a tacky mess.

doe4rae · Post by **doe4rae** » Mon Jun 21, 2010 11:18 pm

I did investigate the pieces I cut off and I was pretty sure there was no fiberglass in them. I could break them apart with my fingers like a potato chip. Don't know how much the epoxy alters the flex of the fiberglass but I hope it isn't that brittle! I also think I am feeling and seeing the weave of the cloth on the surface beneath the bubble. I doubt myself now in light of the more recent comments. I'll have to examine it again in the morning. A little concerned what acetone may do if the fiberglass is ok and I only removed varnish/epoxy. I also wonder if my brush that I used to varnish would have happened to have some mineral spirits left in it from cleaning....could it act as a solvent on the epoxy? Or if I had sanded too aggressively .. down to the.glass and didn't notice perhaps varnish would do this? I guess one way to find out if it is uncured epoxy is to tie the canoe to a dock for a whole day when we get our next 90 degree day? Sigh.

DSJ · Post by **DSJ** » Mon Jun 21, 2010 11:47 pm

If it was my canoe, I'd clean away the sticky stuff, sand lightly, and touch it up with a bit of varnish.
Full repairs can wait till the end of the season. Right now its time to be on the water!
For repairs during a trip, duct tape is all you need.

Glen Smith · Post by **Glen Smith** » Tue Jun 22, 2010 11:15 am

Dawne, it does seem the glass is intact. In that case, I would feather-in the surrounding epoxy and lightly sand the affected areas going out 1" beyond damage. Apply 1 or 2 coats of epoxy, let harden then go paddling. It can be varnished later.

Tim Eastman · Post by **Tim Eastman** » Tue Jun 22, 2010 12:39 pm

Glen Smith wrote:Dawne, it does seem the glass is intact. In that case, I would feather-in the surrounding epoxy and lightly sand the affected areas going out 1" beyond damage. Apply 1 or 2 coats of epoxy, let harden then go paddling. It can be varnished later.

Sounds like you and Glen are on the same page. This is what I would seriously consider as well. Should go fine I'm thinking.

doe4rae · Post by **doe4rae** » Tue Jun 22, 2010 1:40 pm

Sounds like a plan.

I know why it could have looked like the fiberglass was in the cut out piece... when it was still "hot" immediately after flipping the boat over I pushed the bubble down -- rubbed, back and forth a bit over the surface with my finger trying to see if there was water under it and I think whatever was "loose" (epoxy? varnish?) within the weave of the cloth stuck to the surface of the bubble, creating the impression of the weave but not the actual cloth itself. The cloth now looks about like it did with my first coat of epoxy on it. Not with fibers showing but with the weave texture plainly visible. I don't know if this means my first coat of epoxy cured and some part of the second, third, or 4th coats didn't, or if something happened while varnishing.

I guess time will tell. :smile

Thanks for your answers.

Tim Eastman · Post by **Tim Eastman** » Tue Jun 22, 2010 1:55 pm

Dawne I just took another look at your 360 and 361 photos. Looking at the play of light immediately to the left of the larger bubble I'm thinking that you have some contaminated adhesion there as well. As others have said the corruption seems to be between the last (top) layer of epoxy and the varnish.

I'm thinking it was a chip of varnish in your hand that you could break chips off from. Epoxy is pretty tough and probably wouldn't be able to break like a potato chip. You did mention that things were sticky under that chip so that tells me something never fully cured.

In any case I'm thinking you should encompass (by excavating around) both voids and feather out beyond them 1" like you're thinking. If the epoxy is undamaged you're in pretty good shape. If the epoxy is still tacky though you will have to remove some down to "known good" epoxy.

Best of luck and post pics when you have them.

The Bear Mountain Boat Shop

Trouble! "Blisters" on the underside of my canoe

Trouble! "Blisters" on the underside of my canoe

update...