The building material plywood is frequently used for a wide range of tasks, including the construction of homes, shelving, and shipping containers. A regular sheathing grade of plywood might not be the best choice when it comes to building certain types of durable structures, such as boats and cabinets. Marine-grade plywood outperforms its sheathing cousin in terms of durability, stability, and appearance.

Marine-grade plywood, also known as simply marine ply, is not always what it appears to be. That is, it is not watertight. It is a high-quality hardwood plywood made with waterproof glue, but it is not rot-resistant because it has not been chemically treated. Better grades are also lighter, stronger, and virtually defect-free. These characteristics are what make this plywood a popular choice for boat building and boat parts. It’s also an excellent choice for long-lasting outdoor furniture projects in coastal areas, especially when treated with a strong protective finish.

Different Grades of Marine Plywood

  • A-A
  • A-B
  • B-B
  • Medium-density overlay (MDO)
  • High-density overlay (HDO)  


In the 1930s, Dutch door manufacturer Cornelius Bruynzeel developed marine grade plywood, which was used to construct boats during World War II. Douglas fir or western larch are the materials used today in marine grade panels. Contrary to what its name might imply, a panel is not innately highly resistant to rot and moisture. A marine grade plywood must be sealed with a water-resistant material, such as paint, varnish, or polyurethane, or treated with a preservative to avoid rot.

Marine Grade Plywood V Sheating

The number and quality of veneers, as well as the type of adhesive used in these premium panels, distinguish Marine Grade plywood from other types of plywood. Normal sheathing plywood is made with fewer, thicker layers. Standard plywood interior veneers may contain voids and larger knots that are not visible until the panel is cut. Water infiltration through unfilled edge voids can cause rot or delamination. Marine ply, on the other hand, is made of many thinner layers with no voids or large knots.

 To give panels strength, all plywoods alternate the orientation of veneers, but the use of more as well as full-face veneers is what provides Marine Grade plywood its greater long-term stability as well as improved fastener holding quality. Marine panels are also made with an adhesive that does not degrade when exposed to water or high temperatures for an extended period of time. This prevents delamination and increases the durability of Marine Grade plywood.

While Marine Grade plywood is a strong panel, it is only used for appearance and has no span ratings. It should not be used in structural applications unless it has been approved by local building code officials first.

Grades of Marine Plywood

Only A- and B-grade veneers can be used to produce Marine Grade plywood, which is regarded as a premium panel. This significantly reduces the size of any knots and the number of repairs that can be made to each veneer. The most popular size for marine grade plywood is a 4′ x 8′ A-B grade panel, which has a “A” grade on the front and a “B” grade on the back. A-A and B-B (“face back”) grades can also be produced, but doing so usually necessitates a special order and a sizable quantity for a mill to take it into consideration.

High-Density Overlay (HDO) or Medium-Density Overlay (MDO) may also be used to finish marine grade panels (HDO). These thermoset, resin-impregnated paper fibre overlays produce a hard, smooth finish that is resistant to dents, scratches, weather damage, and chemical damage. HDO is most frequently used in industrial settings and contains additional resin to produce a shinier surface.

Other Strong Woods

Wood species with natural decay resistance, such as redwood, cedar, ipe, shorea, and cypress, are less likely to rot as a result of moulds and other organisms that feed on the wood. Marine plywood, unlike pressure-treated lumber and plywood, is not pressure-treated to resist decay. This means that if marine ply is going to be exposed to moisture, it needs to be protected with a water-resistant finish. Choose pressure-treated lumber or plywood rated for the expected level of exposure if you need a material that can withstand moisture without a protective finish.

Why is Waterproof Glue used?

The main advantage of using waterproof glue in marine plywood is that when the plywood is exposed to moisture, and even very high humidity as well as boiling temperatures, the glue will not fail, and thus the plywood’s wood layers will not delaminate or fall apart. If you’re making a plywood boat hull, this is an important design feature to consider. If the protective finish on the hull is damaged and the wood becomes wet, the plywood will remain structurally sound.

What distinguishes marine plywood from BWR and PF waterproof plywood?

The concept of marine plywood is very distinct. Marine ply is made from veneers from a few carefully selected species. No specific species will ever be used to manufacture marine plywood. Gurjan, Popular, and Eucalyptus are among the plants chosen. Marine plywood is sometimes made with a blend of different veneer species, such as eucalyptus and popular eucalyptus and Gurjan.

Furthermore, using concentrated or undiluted phenolic resins, like phenol formaldehyde, improves the waterproofing properties of marine plywood significantly. However, before affixing veneers to waterproof plywood of the BWR and PF grades, the adhesives are diluted. Using waterproof BWR grade waterproof plywood for household furniture is commonly thought to be sufficient. As a result, more expensive Marine grade plywood is rarely used for house interiors.

About Gurjone Ply

Gurjone Ply provides you the best quality marine ply in India. Gurjone plywood is made using a multilayer process that prioritises quality and gives it exceptional strength. As a result, your furniture will be much more robust and durable than furniture made of regular wood because it will be thick, strong, and unbreakable. Gurjone plywood is a high-quality premium plywood that is resilient, strong, and can withstand everyday use without losing its tensile strength.

 When it comes to producing high-quality wood products like amrine ply Gurjone Ply is the best option for all your needs and requirements for the best plywood in India.