Re: Epoxy screws
the only difference with underwater epoxy is that it uses curing agents etc. that don't react with the water during cure...
epoxy is sort of a medium hard plastic - not very strong or scratch resistant. The epoxy you used is known for it's brittleness.
bond strength is a surface area issue. - you want to get max surface area - ie. the bottom of the al. strip.
one common fix is to mix sand into the epoxy and spread over the worn areas. When that also wears down you mix up a bit more epoxy and sand and reapply.