I did some tests and the glue stuck, but it wasn't the greatest bond. However, I also mixed a bit too much dye and the glue itself cured a little weak. It is best to put a piece of cloth over the underside part of these to hold them in. The way these work in a board is that you drill the hole with a forstner bit, set them in the hole (remember, this is in a foam board where you are recessing them into the foam), and then you fill around them with epoxy. Apparently as discussed the epoxy wedges them in, so you do need to support them from behind. In this test I used thickened epoxy around them and it holds enough that you can't push it out with your finger when pushing from the deck. I decided to step-drill the hole so there is a step for them to rest against from underneath.

I have never had one of these fail on a board. The leash itself will typically go before these do. I'm sure someone out there has had it happen, but I have not. They are perfectly strong, but again they are designed to be set in from the deck and recessed into foam or wood. For wood surfboards I install a wood block where I intend to put the leash cup and once the board is done I drill from the deck with a forstner bit and install them. With a kayak you have the problem of a 1/4" or so thick surface that is hollow below. That's why I say it is best to support it from below by putting a piece of cloth over it. They are step-cut so that they are smaller at the top than the bottom, so the epoxy wedges them in, but I do believe it's best to support them from below in this application.