if it is above the water line just make up a strong sand cement mix with a concrete bond in it and apply it to the chipped area. If it is under water you may have success with an underwater epoxy putty.
If it is gelcoat finish just clean out the chip, get all the loose material out, get a tiny bit of gel coat, add a few drops of catalyst and fill it in. Tape over it if need to hold it in place, or...
First question. Does it leak?Second. Is it structural?Third. How noticeable is it?It might be better to leave it alone unless one of the three questions asked is negative.If it leaks, drain and hot...
simple you cant. I can be done, but only using a Methyl Methacrylate Adhesive. Do not allow fiberglass to be used for the repair, all plastic steps manufactured to date are made of ABS plastic...