Marine Plywood

Marine plywood is a kind of plywood that has been constructed using waterproof adhesives to make it suitable for use in humid environments, including boat, the sub-floors of a home, the sheathing of a utility shed’s walls, boat house and structures of other kind. It may serve as the underlayment of boat’s deck, the backing of the wall voids, compartment up panels on the boat, and may even be part of the boat’s hull.

Features of Marine Plywood

Chinese marine plywood mostly use cedar or other woods for the veneers. All plies of marine plywood are at least B grade, with knots, but no knotholes. The panels are glued together with waterproof structural resin. The core may have void less than 1/8-inch.

The Size

Marine plywood sheets are made 4 x 8 feet, or 5 x 12 feet, with thicknesses of 1/4-inch, 3/8-inch, 1/2-inch, 5/8-inch and 3/4-inch. These can be used on a boat or ship, or in a residential setting requiring a waterproof plywood, for example sub-flooring. Marine plywood is available with veneers in grades A-A, A-B, B-B, Medium Density Overlay (MDO) and High Density Overlay (HDO).


No anti-decay chemicals are applied in the manufacturing of marine plywood, but pressure-treated marine plywood is available. It is both rot-resistant and insect-resistant. Some of Chinese Made plywood, such as cedar marine plywood, are rot- and insect-resistant by the nature in their manufacturing.

History of Marine Plywood

Marine plywood played a role in the 1944 D-Day Invasion during World War 2. Many soldiers arrived on the beaches of Normandy in “Higgins Boats,” the brainchild of Frank Higgins, who convinced his father, Andrew Jackson Higgins, president of the Higgins Boat Company, that marine plywood was the best material available from which to build the Landing Craft Personnel.


Only the adhesive of Marine Plywood is waterproof. If you want to use marine plywood in a humid, environment, it should be painted and all joints caulked.