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• /Wooddata.pdf

By: Bernd Kohler <ikarus342000@...>

Description:
Some data of wood I use for my boats. Attention, Meranti, I do not recomment

Very interesting. Is this data for these species as timber? or as plywood??

^{The properties of the wood will not change, of course. The veneers of the wood are glued at 90? to each other.}

^{So Birch plywood will be, for example, double as flexible as Meranti plywood. I made the table base from
Birch plywood with a diameter of 60 cm without any problem.
Weight:? 1 m2 4 mm Okoume plywood weights 1,8 kg, 1 m2 Meranti 2,84 kg. By the way, many say
Birch will rot easily. In the wood epoxy composite system, this is not true. The aft beam part of the PELICAN
is made from Birch plywood. Ask Paolo, who sails the boat now. It is as good as the first day. The boat is now 33 years}

Interesting data. I have used okoume plywood since 1975 and have a habit of weighing it before using it. So here are a some real world measured data points. 1978 4mm Brunzeel plywood was 32.034 lb per ft^3 (513 Kg/m3). 1984 4mm plywood was 31.570 lb per ft^3 (506 Kg/m3) (unknown manufacturer). 2014 4mm plywood was 29.440 lb per ft^3 (472 Kg/m3) (unknown manufacturer). 2021 4mm Joubert plywood was 30.310 lb/ft^3 (486 Kg/m3).

All of these measured weights are also linked to a thickness. 4mm is not always exactly 4mm. So weight per sheet can vary with thickness as well as density.

We all know wood is variable. However, all of these representative samples are all more dense than the 450 Kg/m3 Bernd uses. Some manufactures, like Shellmarine, use as low as 448 Kg/m3 but I have never seen 4mm as light density and I have weighed 100's of sheets over many years. The lesson is to be aware that weight increase up to 7% due to plywood density increase over the minumum is possible.

On a related subject. I weighed Sande marine plywood at Edensaw Woods in Port Townsend, WA, USA 2-years ago. It averaged 16.82-lb? per sheet for 0.2362 inches thickness (6mm). This works out to 26.82 lb/ft^3 or 428/Kgm3. It is about 1/3 the cost of Okoume and is sustainable. It might make a better Okoume substitute than Meranti. It does not come in 4mm as far as I know. This is something to check with Bernd before using it.

David M

Hi? David
Fascinating that you can still find the weight of a Brunzeel plywood panel from 1978.?
By the way, the Brunzeel factory was in Gabon. He used Gabon as base wood. It is the same as
the light Mahogany variants from Asia we usually call Okoume.
Wood, also the wood veneers used for plywood, is still wood. The weight variation is easy to explain. It depends greatly
on the seasonal variation in the growth rate.?
Humidity is also playing a role. So weight variations of 5 % can be expected.
Interesting the plywood, you mention you can get in Port Townsend.?

Hi, guys. Just such information I would like to read more here.?

Intersting topic. Subscribing. :)