The floor of my 86 cuddy is grey gelcoat.....when I redid my gas tank hatch I wanted to wet sand a few old holes that I had filled from some cooler brackets that had been screwed down....if yours is like mine the problem was the wet sanding took down the non skid on the floor which stood out alot....you may have to paint it if you want to keep the non skid texture.

During my restoration I use Gel Coat simply because I had a lot left over, Just before the Gel started to get tacky I shot it with "Glass Beads" using the same spray gun. It finish the Deck with the consistency of may be a 150 grit maybe? soft on the feet and perfect for traction.
Here is picture of what it looks like on the Gel...

I used 3M Fiberglass Restorer and a varible speed buffer I bought from Sears. I used a wool pad with the 3M polish to remove most all the oxidadated gelcoat then a terrycloth pad and some cleaner wax that gave me a brilliant shine. Wash and rinse well between each application. Be careful using the buffer, don't hold it too long in one spot, keep it moving. Also fill a spray bottle with water and mist the surface you are buffing AT ALL TIMES! I got instructions and tips from my neighbor who has owned a bodyshop for 30 years and is the best I know of. After I rebuilt my transom he color matched the paint and sprayed Emron clear over it with outstanding results.