Using gel coat only is often not enough, when you really want a smooth surface you use:
1. Gel-coat
2. Hardener
3. Parafine (which makes the gel-coat less sticky)

This way the gel-coat can be applied with a small brush and later be sanded with some 400 paper.

I did my Nacra 6.0 last winter and it really looks like new.

Good luck