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Lauan Plywood

Three common questions I field at the CLC phones are: "May I have a free catalogue?"; "Can the Chesapeake Triple be paddled as a single?"; and, "Can I use lauan plywood instead of okoume?" We can dispense with the first two questions with a "Yes" and a "No." That leaves lauan plywood.

Lauan is a tropical hardwood used to make construction-grade plywood. Some folks think that it's suitable for boatuilding. The main -- in fact the only -- advantage of using lauan is its very low price. A 4'-by-8' sheet of 1/8-inch lauan, often referred to as "doorskin" plywood, costs about $10, while a sheet of 1/4-inch lauan, sometimes called "underlayment," will run you $15 or so. On the other hand, okoume plywood, especially in its "marine grade" variety used for building kayaks, is not cheap. A sheet of 4mm okoume costs anywhere from $45 to $85, depending on where you buy it.

What's The Difference Between Lauan And Okoume? To some degree, you get what you pay for. Over the last 10 years I've built at least 4 boats out of lauan plywood, in each case drawn to that material by a limited budget. Every time, I found myself fighting with voids in the core, and, just as serious, failures of the glue between the plywood veneers.

You'll be surprised to learn that the glue used in "exterior" grade plywood and "marine" grade plywood is generally the same stuff. What differs is the care with which the glue is applied between layers in manufacture and the quality of the wood being glued. Manufacturers of okoume, most of them in Europe, must meet various internationally recognized standards such as British Standard 1088, which prohibits voids or dry spots in the glue.

The quality of the cores of the plywood is vitally important to builders of plywood craft. In CLC boats and other kayak designs, there is often a great deal of bend and twist that put the outer veneers of the plywood under considerable stress. While often attractive in appearance, the outer veneers of lauan plywood are very thin. This contributes to the low cost; to achieve the desired thickness the manufacturers can fill up the core with crumbly offcuts of endgrain that contribute almost nothing to the strength of the panel. Conversely, marine-grade 4mm okoume generally has three layers of almost even thickness with no voids, and it only rarely contains seams in the veneers. The result is a panel with very even bending characteristics and a great deal more strength.

What's With The Metric Thicknesses? Because most high quality okoume plywood is manufactured in Europe, it is sized in millimeters. But what's really important here is that lauan plywood is only available in two thicknesses: about 7/32-inch (sold as "1/4-inch"), and about 3/32-inch, (sold as "1/8-inch"). Most of CLC's designs specify 3mm or 4mm plywood. 4mm plywood is about 3/16-inch and used for the hulls of most of our boats. The 7/32-inch lauan underlayment grade is only a bit thicker than 4mm, but enough different, combined with the weak center core, to give trouble with the twist in the bottom panels at the bow and stern. The 1/8-inch variety is a bit thin for hulls without major fiberglass work, and you still may have trouble keeping the hull from being lumpy and flexible.

What If I Just Can't Afford Okoume Plywood: Can I fiberglass The Lauan And Be Okay? Well, consider your priorities. In my opinion, the hull is about the last place I'd want to economize in a craft that will be taking me away from shore. Before I'd trust my life to it, I'd have to slather a lauan hull with $100 worth of epoxy and fiberglass, making the $100 I'd saved in using lauan less significant. To save money, buy plywood in bulk with a group of kayak builders, or ask for slightly stained or damaged sheets of okoume. Consider building your own paddle and seat, scrounging for deck rigging, using less expensive paint or varnish, and holding off on that snazzy paddling jacket before you cheapen the look, feel, longevity, and strength of your kayak.