C-Forum

I'm bought an old Dagger Caption that needs a complete make-over... repair on the hull interior (many cracks in the ABS inner layer below the old saddles and below old anchor patches) and she needs complete new outfitting.

Plan is to repair the cracks in the hull (inside only) using G/flex followed by laminating a large patch of E-glass+kevlar using "normal epoxy". The Epoxy laminate will cover the entire bottom below the bow and stern saddle position.

I need some advise on which glue to use for fixing the new vinyl anchor patches (Mike Yee) to the epoxy laminate. I've heard that 3M Scotch-Weld Urethane Adhesive 3532 would give good results, but can't find that one in Europe, and am not sure about the many other 3M options...

Does anyone has any experience with G/Flex 650 or G/Flex 655-K for glueing vinyl anchor's to epoxy laminate?

Michel

I use regular G-flex for gluing D-ring patches and it works fine. It will work better for gluing to epoxy than for gluing to vinyl Royalex skin.

On your inside patching job, I would use all Kevlar unless you are going to patch inside the chines. E-glass is for outside patching. It doesn't have the strength in tension that Kevlar has. Also, I assume the cracks are mostly longitudinal, running lengthwise. If you bias cut your cloth, so that the cloth fibers are at 45 degrees to the axis of the hull, you will have twice as many fibers crossing each crack.

Thanks ezwater.
By "regular G-flex", do you mean the G-flex 650 ? Do you use it straight from the bottles or thicken it with fillers?

Most larger cracks run lengthwise, but strange enough several cracks follow exactely the circular contour of the old anchor plate/patches... So I have circular and transverse cracks in the ABS as well and lots of small cracks in various directions..
Since the cracks are only below the old saddle positions and below the old vinyl anchors, I think that the old glue must have caused the ABS to become brittle and crack.
Don't trust the strength of the inner ABS anymore so I'll reinforce the entire area below bow and stern saddle position up to the chines.

Michel

I don't know G-flex by the numbers, but I have the regular G-flex, and I have several West fillers on hand for thickening, including microfibers, microballoons, graphite powder, and colloidal silica. It's been a while, but I might have used microfibers as filler.

I agree with your reinforcement plan, but I'm not sure glue was the culprit. The sites you report as having cracked are all sites where "stress risers" were located. That is, the ABS was forced to flex too sharply at those sites.

I'm not suggesting more work, but I would be tempted to skim off the vinyl top layer using a sharp chisel held at a low angle. This would allow the resin and reinforcing cloth to lie right on the ABS. There might be better penetration of the cracks by the resin. West Epoxy and the ABS are much more similar in hardness and flex characteristics than is the vinyl top layer. I could post a couple of pictures of the chisel method if you were interested.

That's exactely what I was planning to do, remove the inner vinyl skin over a large area and apply the glass/kevlar/epoxy laminate directely to the ABS.

Plan is to first remove the vinyl skin. Then open-up and clean out the cracks where possible. The larger cracks with than be filled with G/flex 655-K. After hardening of the G/Flex cleaning of the surface with acetone followed by light sanding (grit 80). I might even consider flame oxidizing as well, but not sure if I dare to do this (sounds a bit scary to put a flame on the surface of a canoe...).
I have access to vacuum bagging equiment, so I'm considering to apply the glass/kevlar epoxy and vacuum bag this in order to obtain maximum bonding to the ABS skin and maximum saturation of the kevlar fibres.

Canoe should be "like-new" after the repair, allowing many years of fun on the river with this hull, especialy now that it seems that Royalex will become scarce