A term applied to certain laminated lumber (plywood). Marine-grade lumber is most frequently used for boat hulls or or marine applications where bending is required. Characteristics include:
- The grade of all the plies must be “B” or better
- There may be knots, but no knot holes
- The exposure rating is “Exterior”
- Sanded on both sides
- Maximum allowable gap inside the core is 1/8″
- The lumber is not treated with chemicals to prevent decay
- All glue is waterproof structural adhesive
Marine-grade woods are used by some manufacturers, such as Mesa/Boogie, for making guitar and bass speaker cabinets.