Subject: Re: [baidarka] poplar for gunwhales?
From: Peter Chopelas (pac@premier1.net)
Date: Fri Oct 12 2001 - 00:57:02 EDT
Andrew asks:
>Any thoughts on using scarfed poplar 1x2's for gunwhales? It is
absolutely clear, light and springy but kinda soft. I'm hoping to find
1x3's of the same.
If this is Yellow poplar, it should be similar in strength properties to
cedar except is has a higher elastic modulus (means it is about 40 percent
stiffer in bending for the same size peice). there is no warnings about
unuasl loss of properties is wet in my referance manuals, meaning it would be
assumed to loose 15% of its strength when wet. If this is not Yellow Poplar
it may not be rated as a structual lumber because of undesirable properties
(like loosing it's strenght when wet). Though, as one of my engineering
professors used to say, a simple test might be worth a thousand expert
opinions. Get a peice and block it up next to a same size peice of wood you
know is good and set a few bricks on it and leave it out in the weather for
the next month or so and see what happens. Try soaking a peice in water for 5
days and take it out and bend it and see how it responds.
>Also, the Home Depot labels some of its lumber as "american wood". What
is this?
In my National Design Specifications hand book it lists the grading
classifications for all of the woods rated and graded by 21 different grading
agencies in the US and Canada and there is not a single category known as
"American wood".
There is an American Beech, but that is a very hard, heavy and dense
hardwood. too heavy (and expensive!) for a kayak frame but good for wear
blocks or to perhaps protect the keel with a strip screwed to the keelson
through the skin.
It is unrated and there is no recognized industry standard for it. It is
likely a category that a local mill made up to lump together a variety of
different unsorted species locally available. Or it might even be a "catch
all" category the Home Depot invented so they can accept any low bidder
delivery from any mill without having to worry about changing the category it
is inventoried in. It could be anything, even within the same mill run.
There is no tree called American wood, and there is no industry recognized
classification for it.
If you find a clear strait grain piece long enough and big enough to rip all
of your parts from one timber it would likely work fine. I would not depend
on any two pieces matching. There is almost no way to know for sure what you
are getting, and I would not depend on anything the salesman tells you.
Why use it? Is it real cheap? If there is no significant price advantage
why take the risk? If there significant savings try a few simple tests on it
and if it seem reasonable use it.
Anything and everything has been used on a kayak frame, even bamboo, no
reason it would not work either.
Peter
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