Alan. I sanded with 80 grit the entire boat. Blew off with compressed air, then wiped down with acetone. Let that flash then mixed up thickened epoxy and filled in gouges and a few holes. Where there’s was complete holes we went ahead and patched with 4oz and then immediately covered with a full sheet of 4oz cloth. Rolled on regular mixed epoxy at about 65 degrees room temperature. When we was done I set a heater under the canoe and set it at 80 and left it for the night.
I peeled the glass as far as I think I can. It looks like it has stopped.
Woodpuppy - Yes all the back the sanded Kevlar. Even has fuzz on the backside of the new epoxy where it tore it off the boat.That’s a bummer. Is the exposed surface the original sanded Kevlar, or the added epoxy layer?
Goonstroke - This spot did not have any patches under it. Just straight cloth to the sanded Kevlar. I used US Composites 635 with medium hardener. Should not of had any blush. As we laid the thicken epoxy patches on. Then immediately laid the new cloth and resin. All with an hour. And it was in the shop in the shade 65 degrees.I wonder if something in the thickened epoxy could have interfered. Did the area of delamination correspond to one of the patches? If the epoxy for the patch had some surface amine blush, that could cause a problem with the next layer. What kind of epoxy did you use?
This reminds me of the delamination I had on a 1984 kevlar ultralight Wenonah, but in that case the glass I was peeling off had been there for years and I believe the issue was age and/or UV damage to the resin. After I patched it with a full sheet of 5oz kevlar, I put some pretty good knocks on it (in one case enough to break some foam core) and didn't experience any delamination.
Mike - Yea. It’s fully saturated,(graphite only no pigment) I do not think what I put on is compromised. I think it is just the bond. Where it is torn from the boat it is clean. All the way back to sanded Kevlar or whatever was left solid on the boat. The pieces even have fuzz on the back side from being torn off. I guess I just did a bad prep job in some areas.Clint, I watched that video again, a couple times.
What strikes me as odd is that the delaminating cloth layer appears fully saturated, graphite black (and black pigment?) through to the bottom of the cloth, but there is not a trace of anything left on the hull as the cloth is peeled off.
That, I guess, has to be a clue of some kind to the adhesion failure, but ???
Mysteries happen. ALSG wrote about recoating the bottom of the stripper he built with a fresh coat of Helmsman Spar Urethane, the same product he had used in the initial build. The new coat of urethane never set up properly.
Helmsman Spar over Helmsman Spar, so it wasn’t product incompatibility. Good prep work, same application technique, done by the same person, so not user error.
I’ve refinished spar urethane with spar urethane dozens of times without any problems. The only explanation I could come up with is that he got a bad can of Helmsman.
So todays findings.Kudos for confessing and even videotaping a fail. I think there is more to be learned, and shared, from some oopsie, even if from unknown causes, than from builds and rebuilds where everything went exactly as planned.
On the bottom it was in such bad shape I had to take it down so far because of whatever the previous owner had put on it. Which I think was "bondo epoxy" from dealing with it in the past. Really hard and brittle. By the time I had it off I was down to the kevlar because the original coating was gone and kevlar was starting to degrade from the sun. When I laid the glass I laid it on dry, positioned it and started rolling on epoxy like you would a strip canoe. It was light fiberglass and never though anything else about it. It wet out really easy and and stuck good.The times I've done repairs like this, I mostly didn't sand to bare kevlar, I just roughed up the resin (vinylester?) enough that there could be some mechanical bond. Broadly speaking, Kevlar is hydrophobic and glass is hydrophilic ... could the glass have more or less sucked the resin off of the kevlar? If the surface of the kevlar is naked and fuzzed, it might be better to paint some epoxy on it, let it cure fully, rough it, and then add glass. I'm obviously speculating as I haven't seen this happen in fresh patches, maybe others here have.
That's crazy how some pieces just pop off for because of the sizing. Perfect sharpie impression!“If that is the case. Peel all the new stuff off and sand again? Wait till it peels off?”
I wouldn’t wait for it to peel off on its own after some minor paddling bump or bruise. As making backwards progress as it sounds I would peel off anything I could, even if that meant trying lift an edge with a razor knife to see if it was free-able.
In some ways, if the failed cloth peels off and removes cleanly, you are ahead on the re-repairs. Sanding glass impregnated with graphite powder is a nightmare. If it comes to that I’d do it outside, with a respirator and full PPE garb. You’ll look like a coal miner coming off a long shift when finished sanding.
FWIW this if the strip of failed 4” E-glass that popped off the sea kayak chines.
At least we didn’t need to try to sand it off the angled chines inside the hull; that would have been awkwardly challenging.
I feel that the "epoxy" job was done correctly. Because all the other things that was done that day and the whole weekend has been fine. Heck even the same lay up just in a different spot is fine. It has to be the surface above the bad kevlar. It just has to be rotten and there is just nothing for the epoxy to hold to. I do not have time to peel and fix the entire bottom before a race in a couple weekends. So I'm going to patch the spot run the race and see how it fairs. Depending on that outcome will determine the time frame on when the bottom will get redone again.Wow, I'm feeling for you Clint. So, it's got to be one of two things, either the surface or the epoxy. Did you say earlier what type of epoxy you used, and its age? I wonder if you somehow got the mixture bad on one batch. Too much hardener??? I accidently used 2 parts hardener to 1 part resin by mistake and the stuff stayed sticky, so I assume that's not what you did. From your video I'm seeing some old stuff coming off with the glass. This could mean that there was a layer of poorly adhered old resin still on the hull in that area. You may have sanded it until it looked good, but it would be difficult to tell. Is there any sign of delamination in any other areas?
Time for a solution. I would flex the hull in other areas and see if you can get any more to delaminate using similar pressure to the stick you ran over, or more! I would even gouge the surface in a few places with something sharp to see if the glass is adhered. Take a sharp scraper to delaminated area and the edge of the glass and see if more will come off. As you know, you can fix just about anything with more glass and epoxy. Hopefully not and the problem is isolated to this one area. If you're satisfied that it's only the one area I would re-sand and either do a test patch in that area or just go for it and re-glass. Keep us posted
Good luck, Mark
Sorry to repeat some of what was said above, for some reason I wasn't seeing the more recent posts.
goonstroke - Thank you! We where also surprised at how well it held together. I was not sure how else to do the bottom without it falling apart. I am not scared to do it again and will say that the boat is bullet proof now. I'll take it anywhere. To add to the stress test, we crossed the bay at the end of the race. Two crossing one about 3 miles and another 1.5 miles with 3-4 waves. Handled it great, I was worried with that much torque on the complete boat going over the crest and valleys it would fine the weak spots and work it apart. With all we did to it, it added 17lbs. If I did it again I would peel the inside off also to save on some weight. We was running out of time and could not afford the time to take it our on this one.Nice work on the Safari! It's absolutely amazing that that boat survived it, after all those late day radical repairs and low water to boot. I've never seen a canoe re-bottomed that way -- bold.
That tree limb photo is awesome. Wenonah's classic kevlar ultralight layup is not exactly bombproof even when it's virginal, and the breach usually ends up right in front of a rib. Maybe you need to wear shin guards!
I think my words was something like "OH $HIT!" as it was picking me up and rolling me out the back of my seat. Had a big goose egg on the bottom of the leg for about a week. Made it tinder to sit in the office chair for the next day.“Every time we took the boat out to train in it if we hit something it would damage the boat. Sometimes it was a minor scrape that would result in a delamination like above. Or it could be a major thing like a limb all the way through the boat and almost through my leg”
Clint, there are some scary canoe photos, starting on post 1 and throughout your rebuild, none more so than that hull poking log. I’d love to know your exact words when it burst through at your legs.
I believe it did. When I went to do look at it we took it off of a rack outside. And of course it was on top.I gotta ask, did Peanut Brittle spend its previous life baking fully exposed to the hot Texas sun?
That would be an easy way to portage the boat maybe. Put some heavy duty suspenders on it.I was always concerned that someone would stand up in it and go full Flintstones car-style, stuck half way through the hull from the waist down.