Marine Plywood Requirements
Standard marine plywood as defined in BS 1088 should have outstanding resistance to biodeterioration (durability) with time. The biological durability of marine plywood is expected to be greater than that of plywood of the same species that meets the requirements of BS EN 636-3. In this respect, Standard marine plywood should be made throughout of timbers having a durability rating of class 3, BS EN 350-2, or better and a nominal density of > 500kg/m3 and up to 5% sapwood per veneer is permitted.
Number and thickness of plies
According to BS 1088, Marine Plywood panels having a thickness of 6.5mm or less should have three or more plies. Panels having a thickness of greater than 6.5mm should have five or more plies. With 3-ply panels, the combined thickness of the two outer plies after sanding should be between 40% and 65% of the nominal unsanded thickness of the panel. With 5-ply panels, the combined thickness of the two outer plies after sanding, combined with those of the core and other inner plies with their grain direction parallel to the outer plies, should be between 40% and 65% of the nominal unsanded thickness of the panel. Additionally, for panels with nominal thicknesses of greater than 3.8mm, each outer ply should not be less than 1mm thick after sanding and each inner and core ply should not be more than 4.8mm thick.
In accordance with BS 1088, all marine panels should not contain any of the following manufacturing defects: open joints (e.g. core gaps, overlaps and pleats, blisters, hollows, bumps and imprints), roughness (other than that due to the irregular structure of the wood), sanding through, foreign particles, defects in the edges of panels (e.g. due to sanding, sawing, missing wood).
All marine plywood as defined in BS 1088 should have outstanding resistance to loss of bond strength with time. When tested in accordance with BS EN 314-1, the bonding quality should meet a minimum requirement of BS EN 314-2, Bonding Class 3.
Panels conforming to BS 1088 should be indelibly marked on the back or edge with the following information in the order shown:
1) The number and date of the British Standard "BS 1088-1:2003" and the word "MARINE"
2) The word "UNBALANCED" if panels are of unbalanced construction
3) The word "TREATED" if there has been any application of preservative treatment
4) The nominal panel thickness
5) The manufacturers name or ID mark
6) The country of manufacture
7) The panel type (Standard (S) or Lightweight (LW))
8) The name of the timber species according to BS EN 350-2:1994
In addition, the documentation for each consignment of panels should include the marking information above and a list of all the species used in their construction and details of any preservative treatment which has been applied.
Both parts of the British Standard BS 1088 Marine Plywood are available for purchase through the TTF. Members can also Click Here to read the full NPPD Panel Products Code of Practice.