Marine plywood

In construction, marine plywood is a specially treated plywood that is designed to resist rotting in a high-moisture environment. Marine plywood is frequently used in the construction of docks and boats.

Advantages of marine plywood

* Durability - small scratches through painted plywood may expose the interior to water. Inexpensive plywood may not last long when it is damp
* Strength - marine plywood is stronger and has consistent mechanical properties: no voids.
* Workability - marine plywood is usually easier than fiberglass to cut and bend
* Resistance to Warping - marine plywood (with the exception of Fir-based plywoods) will resist warping or check

Disadvantages of marine plywood

* Cost - Marine plywood is much more expensive than standard plywood. Costs for a typical 4 foot by 8 foot 1/2 inch thick board is roughly $75 to $100 US or around $2.5 per square foot. This is about three times as expensive as standard plywood.

Marine plywood comes in several common thicknesses:
* 1/8 inch (3 mm)
* 1/4 inch (6 mm)
* 3/8 inch (9 mm)
* 1/2 inch (12 mm)
* 5/8 inch (15 mm)
* 3/4 inch (18 mm)
* 1 inch (25 mm)

Standards and ratings

Marine plywood can be graded as being compliant with BS 1088, which is a British Standard for marine plywood.

There are few international standards for grading marine plywood and most of the standards are voluntary. Some marine plywood has a Lloyd's of London stamp that certifies it to be BS 1088 compliant. Some plywood is also labeled based on the wood used to manufacture it. Examples of this are Okoume or Meranti

Alternatives to marine plywood

There are several alternatives to marine plywood. Some of these are engineered materials. Examples include fiberglass-type composites using glass, Kevlar, or graphite fiber, and bonded materials using lightweight cores such as expanded polystyrene or honeycomb.

References

PS1-95, Construction and Industrial Plywood, Plywood Design Specification, Engineered Wood Construction Guide, American Plywood Association [http://www.apawood.org]