I recently did the non-skid on my decks. I used glass beads as per bead-blasting to get the texture.
I masked, painted the decks with a roller, then while the paint was wet, sprinkled glass beads using a flour sifter.
Next day I blew the excess loose beads off, and rolled on another coat of paint.
The glass beads are available in a couple of sizes, so you can have as coarse or smooth a finish as you want. I went fairly coarse, the advantages being that the glass will pretty much never wear out, only the paint, and I can repaint at least a couple of times in future and still have good grip.
Another plus of glass beads is that when the paint wears off they don't show up black - the decks actually get a bit of a sparkle to them, as the glass beads work like the reflective paint used on roads.
I used the same colour as the rest of the boat, the texture makes it look just a little darker.