[Tim Netherton]

What would give me the best finish on marine plywood in direct sun. Spar varnish or polyurethane? Is there something else on the market that would work better. Can not use epoxy do to health problems. This is going in a boat for the floor and the sides.:boat:

 

[Steve Neul]

What would give me the best finish on marine plywood in direct sun. Spar varnish or polyurethane? Is there something else on the market that would work better. Can not use epoxy do to health problems. This is going in a boat for the floor and the sides.:boat:

Hands down the Spar. Polyurethane would crack letting water under it and then soon fail because it is a interior finish intended to be harder and more scratch resistant. Cabot makes a pretty good spar varnish but if you are looking for the best I would recommend using Epifanes marine grade spar varnish. It is formulated for the deck of a boat. You would find it at places that sell boat supplies.

 

[Fred Hargis]

Yep, the Epifanes is generally considered the top drawer true spar varnish. Just be sure to avoid anything that has the urethane resins in it.....they don't play well with UV. Spar varnishes with urethane resins are imposters.

 

[HowardAcheson]

Spar vanish is not a good choice for a boat floor or deck. Spar vanish is formulated to be soft and flexible so it remains protective as the wood underneath expands and contracts with changes in moisture content. Being soft, it is not very protective and will be damaged if it's going to be walked on or otherwise abused.

Go to a marine supplier or marine hardware store and get someone to help you find a good exterior (non-poly and non-spar varnish. A non-spar varnish will hold up much better.

 

[Quickstep]

What Howard said..... plus, varnish will be slippery when wet.

The best choice for a floor and direct sunlight would be marine deck paint with non-skid in it.