I've done the Buehler's Backyard Boat Building thing for years....
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The floor of my 14' Lund is painted plywood with playground sand for traction.
I'm lucky to have a Re-Store and Habitat for Humanity in town for recycled/reusable building materials. In addition to the plywood pieces, I picked up some second hand gray exterior paint there.. Once the floor's measured & ready to be fitted but before installation, I gave them a coat of paint and then sprinkled with sand. Once the paint dries and the sand is held in place, give it a 2 or 3 more coats of paint to further hold the sand in place and you're good to go.
Here's the most recent piece, installed at the bow last fall.
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Should the sand flake off after use, I still have traction from the dimple of paint that once held the sand in place.
Uber cheap and fairly simple to do.
Mike d