Check on Google. The process is complex. There are two types of gelcoat, one with a surfacing wax and one without. Gelcoat will not vure if exposed to air. So ypu either need the wax type or something to cover it like wax paper or liquid or spray wax. Any of these can change the surface and require sandimg and doing over. For small jobs I use wax paper. Big jobs really need to be spayed indoors in the winter with heat lamps.
I can tell from uncounted hours workimg with two part epoxy paints and gelcoat, that you are better off painting
. It is very esy to grind out crack, fill and fair the a few times until perfectly smooth, prime with two part epoxy paint
, like Interlux 2000E, and deal with all the solvents, sanding and washing to do a two part epoxy paint job, than it is to do gelcoat repairs.
With gelcoat ypu might find it does not set up or it takes a whole winter to dry. Or you cpuld have a gooie mess to scrspe off. At least if you paint you are assured good results in a timely manner.
All that bfing said, if I only had a few little cracks, and I did not care if the color match was perfect, I might attempt a gel coat repair.
Do a search online and read everything you can about it first, and do not ignore any warnings. Be sure to use the wax type gelcoat, and you msy have satisfactory results.