This is also known as epoxy putty. You just push it into the damaged area and allow it to go off. I'll allow Ding All to explain.

 "A hand-kneadable, specialty epoxy putty that mixes in just one minute for permanent repairs to damp, wet areas. Epoxy Stik contains a fading blue dye and becomes fiberglass white after mixing. It may be applied underwater in either fresh or salt water and will bond to substances such as fiberglass, epoxy, wood, glass and metal. Epoxy Stick will not yellow."