polyester vs epoxy resin for underwater gelcoat

[efiedler]

Hi - I have some gelcoat dings I need to repair. The dings occur under the waterline. I have read that for all under waterline repairs, the resin of choice to use is epoxy resin. However, I have also heard that gelcoat will not adhere to expoxy. The dings will be gelcoated over after the resin is applied. So should I go with epoxy or polyester resin?

[Jeff_H]

There is absolutely no reason to gelcoat underwater repairs. Epoxy is a very superior material to polyester for use on underwater repairs for all reasons. Better adhesion and impermiability, easier to work over time, etc. If you feel that you absolutely need to have a gelcoat finish over the repair, then use vinylester resin which is a close second to epoxy but which will accept gelcoat.

Jeff