Marine board: what it is, sizes and grades

What marine board is

The name covers two different things. In Tanzanian shops, marine board is plywood: thin layers of wood veneer glued crosswise into a stiff sheet, sold as a grade meant to put up with water. Kamaka in Dar es Salaam, for example, files its “marine plywood” sheets under a category called Marine Board. Outside construction, “marine board” can also mean a white plastic sheet used on boats; that product is covered further down.

Whether a given sheet deserves the word marine depends on how it was made and glued, not on the label. The sections below show what to check.

Marine board size in Tanzania

Three Tanzanian sellers published their range on 12 November 2026:

Marine board size in Tanzania

Seller	Thicknesses listed	Sheet size stated
Zanzibaba Timber, Zanzibar	12 mm, 18 mm	1220 × 2440 mm (4 × 8 ft)
Kamaka, Dar es Salaam	12 mm, 18 mm, in two product names	not stated
ASHUBA	12 mm, 18 mm	not stated

The lists show two thicknesses and one stated sheet size, 1220 × 2440 mm. Ask for the size in millimetres before you count sheets for a job.

What makes plywood marine grade

The reference document is the British standard BS 1088, Marine plywood, last revised in 2018. Its published summary on Intertek Inform says it sets two classes, standard and lightweight, for boats and other marine and waterway uses; that it deals in particular with resistance to decay and with loss of bond strength over time; that it also considers marine plywood in building construction; and that the veneer species are chosen for density and resistance to decay.

The glue is the other half. LABC Warranty, a UK building warranty provider, explains in its plywood specification guidance that EN 314-2 class III bonding is for unprotected exterior use or frequent wetting, and that a sheet marked EN 636-3 is fit for exterior conditions. A board without BS 1088 or an EN 636-3 marking is not shown to be marine grade, whatever it is called on the shelf.

Where it is used

ASHUBA’s product description gives the main use on Tanzanian sites: the board holds concrete in place while columns and foundations are cast. That is formwork, and our page on formwork and shuttering covers it in detail. BS 1088 itself is written for boats and waterway work, with building use also considered.

In each case the board is exposed to water: wet concrete, rain on site, or splashes. That is why the glue class is the first thing to check.

White marine board is a different product

Searches for white marine board often lead to plastic sheets. King Plastic, a US manufacturer, describes its King StarBoard as a marine-grade high-density polyethylene (HDPE) sheet that will not rust, delaminate or rot when exposed to UV light, humidity or water, and that can be cut with ordinary woodworking tools (King StarBoard). It is solid plastic, not plywood, and is used for boat fittings and outdoor furniture, not for concrete formwork.

What to check when you buy

1. The marking on the sheet: BS 1088, or EN 636-3 for exterior use; EN 636-2 covers humid interiors and protected spots only.
2. The thickness in millimetres: 12 mm or 18 mm in the lists above.
3. The sheet size: 1220 × 2440 mm is the one size stated in the lists above.
4. The product name printed on the board, since one shop sells two names at different prices.
5. The edges: look for gaps or loose veneers.

Marine board price and Zanzibar

Listed prices from two sellers, with the date they were checked, are on the marine board price page. For boards on sale on the island, see plywood in Zanzibar. Kitovu does not sell marine board; it sells building materials from stock in Zanzibar.