I haven't had the chance to use it yet, but I think you could add some non-skid additive to Duratec and spray that where ever you wanted a slip free surface. From what I have been told Duratec is like a clearcoat. It can be added to gelcoat to improve uv-resistance and flow out when spraying,(less sanding) or it can be sprayed by it's self over a existing gel surface to restore it providing the the surface is consistant in color, (won't cover repairs,etc). I believe it has to be kicked with MEK when used by itself just like gelcoat

Hopefully some else that has used duratec might comment.

I guess another way to go might be to tape off the areas you want non-skid and just spray gelcoat. It generally is quite an orange-peel surface and that can be exaggerated with spray technique. Nice thing about that is if you don't like it you can sand it off and try something else. You can add the additve to gelcoat and spray that on or even roll it on. You most likely should experiment with these or any suggestions before applying to the boat.

My thoughts here are dealing with gelcoat only based on what you said earlier about paint.