Came across a product that seems to do a good job for a non -slip finish
My deck was coated with "non slip paint" but had become a little slick, (especially when trying to get a good footing in a decent swell.)
So found this product at Home Depot. Comes as a thick black paste that you apply with with a plastic spreader. I masked a shape off and made a couple of enlarged footprints either side of my pod seat, to get a good grip. To make it even "grippier" I ridged the paste with a rulers edge to form a deeper tread.
The stuff dries in an hour or so and is rock hard. Sticks to all surfaces including fiberglass/wood metal etc
Great surface with no chance of slipping. Just hope it wears well, as it really seems to do a good job