You can achieve a textured gelcoat finish by applying it with a Brown Carpet Texture Paint Roller Cover.
It is also possible to duplicate the original nonskid pattern with gelcoat. The process involves making a mold of your existing nonskid (video: https://www.youtube.com/watch?v=UpsRljqBH0o), or you can purchase a flexible nonskid mold material.
Flexible nonskid pattern material can be purchased from a company like Gibco Flexmold. They offer patterns that match some common boat brands. Nonskid molding repairs are generally best for small patches.
What can be used to get a textured non-skid surface with Gelcoat?
