You can also add it to the paint and spray it on or you can spray one coat of paint on then using something like a salt shaker, shake some additive onto the wet paint then recoat with paint. This is a good way to do smaller areas.
I would use the finest additive you can find.
Less wear on you and your gear.
From personal experience sailing hp dinghies. Emphasis on "the finest additive you can find". Otherwise you'll be replacing trap harness, boots (barefoot not an option) maybe a wetsuit every season or so and you'll end up with some nice scars on ANY exposed body parts. Tape some 120 grit on the hulls and check it out.
