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Help choosing 4x8x20 Douglas Fir to Resaw for Tanenui Build

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abosely
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Joined: 03/14/2015 - 22:39
Help choosing 4x8x20 Douglas Fir to Resaw for Tanenui Build

I could use some guidance on picking out 4x6 & 4x8 20' Douglas Fir to be resawn for my Wharram Tanenui build.

It's very beautiful wood. No. 1 & Better, air dried, straight grain. I can pick thru & choose my pieces. I'll need about 12, 4x8x20 or 16, if 4x6x20. Or combination of the two widths.

I saw them a few months ago when looking for a house project. Was amazed at the quality of the beams! Straight, no knots at all, really nice lumber, it looks like cabinet grade wood.

When I get the 4x6/4x8 home I'll resaw them a fat 1/6" over size & let them dry & relax for a few weeks. Then finish them to final dimentions.
Most of the sizes needed are ¾"x2" & 3", 2"x2" and a few pieces for crosbeams 5-½" wide or so.

I know I want grain that runs a long way before crossing 1" out of line.
But how straight is straight enough?

I'm guessing they will be flat sawn mostly. I didn't pay real close attention when was there last.

What are some likely ways they will be sawn & what do I want?

When I resaw them I can cut them to optimize grain direction. But don't know what that is!

If anyone has links or any help, ideally specific directions it would be most helpful and appreciated!

I have been a contractor for many years. It's just laying out & resawing for optimum strength for boat building is new. Not resawing lumber.

Cheers, Allen

admiralmanhattan
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Joined: 06/14/2015 - 13:08
The cut of the wood.

First things first, where are the pieces of lumber going to be used? Some times its best to use plain sawn lumber in certain areas, then again useing quarter sawn lumber. (In terms of strip planking the hull.) But if you are going to use the lumber for say the deck beams then, and I may be wrong here, I would belive plain sawn would be ideal. Again I could be wrong here. as in that case the plain sawn board would act as a quarter sawn piece, being wider. Noticing the resemblance in the cut.
If it were me I would probably sit and meditate on my lumber to see which pieces were cut (If plain sawn) from left to right as the grain usualy ends on a point if you can picture that. Meaning the board would likely concave or concove. So to explain this, if I cut a board from a log, and looking at it left to right as a matchbook fold the pieces on the left I would assume would have the tendancy to concave more from the center of the board outwards. Or as we say in the construction filed it would crown from the center towards the outside "from" the center of the board instead of what we usually deal with as a facia board will crown from from end to end at the center giving rise within the length of the board.
Again if its eight inches and twenty feet long, from the eight inches across is where I would be concerned the concaveing would be (the bend in the board or cupping) 
This is why in some applications it is better to quarter saw vs plain saw.
However if you are going to be using them for the beams then I would look at the cupping of the board. That I assume is your question? When exposed to water for a length of time I would assume even douglas fir would cup. Knowing your matchbook of cuts or studing your grains to see which are longer or wider from the length on one side to vs the other possibly being smaller and shorter would tell you where the board was cut from.
I have not provided links to an other websites as I do not wish to promote other websites. However it is possible that you could try boatdesign.net as the discussions rage at length. [img]/site/sites/all/libraries/tinymce/jscripts/tiny_mce/plugins/emotions/img/smiley-smile.gif[/img]

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