Yes, TotalBoat TotalTread Non-Skid Marine Deck Paint can be applied over gelcoat.

To prepare the gelcoat surface, clean with TotalBoat Dewaxer & Surface Prep Solvent and sand with 220-grit sandpaper. If the gelcoat has texture, it’s recommended to sand it level using 60–80 grit. After sanding, wipe the surface down again with the dewaxer, and allow it to dry completely before applying the paint.