It could be gel coat, it could be a really bad paint... In any case, you really need to know which it is, since the preparation is going to be a bit different depending... if it is a bad paint job, you'll probably be best off removing the previous paint, since the new paint can only adhere well to what it is on top of. If it is gelcoat, you might want to try Maine Sail's polishing techniques first, since if there is enough gelcoat there, you may not need to paint. Once you go the painted route, you have to keep up the maintenance on it.
BTW, I'm a big fan of sanding off any antiskid and then masking off the areas where you want to apply anti-skid and just applying a good anti-skid coating if you're going to be painting the boat anyways. It makes prepping the deck a lot simpler, since properly cleaning and prepping patterned gelcoat is almost impossible.