-- Last Updated: Jun-18-13 2:05 AM EST --
I have been reasonably pleased with Vynabond. I actually attached to a Kevlar boat, but I think it's the resin (vinylester, in my case) that matters, not the cloth. I bonded in vinyl-backed daisy chains, to which I attach cord to hold my flotation bags in place. People have told me that the bond isn't strong enough to withstand serious pressure from whitewater, and I believe them. But I don't paddle any significant whitewater, and the bond is strong enough for me to do rescue practice without forcing the bags out.
The only aspect that made me unhappy is that after five or six years, the bond failed, and one daisy chain started flopping around. As far as I know, no pressure was needed to make this happen; the bond just wore out. Presumably it would have failed earlier if I had put pressure on the bond at the right time. I repaired with more Vynabond.
So I wouldn't recommend Vynabond on a composite boat for a life-critical application or an application where lots of force will be applied. For my more casual use, I am okay with it, and your use sounds even more casual.
I agree that it forms only a mechanical bond. As far as technique, I combined the manufacturer's advice for use on composites (on their website, not on the can) with advice I got on this board (maybe from Clarion). Unfortunately, I can't remember exactly what I did. I know I used sandpaper and acetone to prepare both surfaces. I seem to remember using my camp stove to heat (gently!) the vinyl surface after the Vynabond had dried. But that might have been some other crazy project -- don't quote me. For the more recent repair, I didn't use heat; I just prepped the surfaces, smeared thinly but thoroughly, let dry, and pressed together. That was in the fall, so I don't have long-term data; so far so good.
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