attaching D-ring patch to kevlar

I want to install flotation in my Bell Magic with either hypalon or vinyl D-ring patches. I want an adhesive that is safe for kevlar and will make a strong bond with the patch (not sure which would would would best, hypalon or vinyl). Any help would be appreciated.

I’ve seen people advise painting
several coats of Vynabond onto Kevlar, and then applying the vinyl D-ring as if the boat were Royalex. I wonder whether that can work well, because Vynabond really doesn’t have much “stuff” to it.

I have used G-flex for that application. It is necessary to put some scrap foam over the D-ring patch, and weight it with a sandbag or whatever, to make sure the G-flex is squeezed to a reasonably thin bond. As long as you clean the surface with acetone, after sanding a bit to raise a few fibers on the patch and the hull, the G-flex will provide a powerful attachment.

I could never trust the Vynabond trick for my canoes with Kevlar interior, because thigh straps and such can put very high tension on the bond.

I had the same question
I asked someone at the local paddling shop about this, and they said to just use Vynabond, the same as one would with a Royalex boat. I never did install the D-rings because I suspected that this might be poor advice. I like g2d’s idea a lot better. I suspect that even “regular” epoxy would be a whole lot better than Vynabond, as long as the hull were prepped first.

Thanks for posting the question. It makes me think about installing D-rings soon on one of my composite boats.

experience with vynabond
In fall 2006 I used Vynabond to attach Bell daisy chains (vinyl backing, nylon loops instead of metal loops) to my Kevlar hull. Then I created a cage through the loops for float bags. I was pleased with the result until a few weeks ago, when one of the daisy chains came partway off. It was right after I loaned the boat to somebody, and I half-suspect he abused it, but I can’t be sure of that. Also, I imagine epoxy would resist abuse better.

Until that day, I could tug hard enough on the Vynabond bond to deflect the boat significantly, without the bond giving way. And I capsized the boat many times (on purpose!) with no problems with the flotation.

So I have mixed feelings. I certainly wouldn’t trust Vynabond in whitewater or for risk-of-life applications, but 5.5 years ain’t bad, and I’m pretty sure my solution was lighter than a solution using D-rings and epoxy and glass cloth. (I didn’t consider a solution using D-rings and G-flex at the time.) I plan to repair the problem with more Vynabond and see how it goes.