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PeterSibley
05-05-2017, 04:00 AM
I'm slowly accumulating fir, mainly used rafters in 2 x 10 and 2 x 8 sizes for eventual use as strips in a strip planked hull. I've been only choosing the higher ring count material, 10 rings per inch and finer.I have no real data to base my suspicion that a finer ring count will provide a better result.

Am I justified in my suspicion or should I widen my choices ?

Peerie Maa
05-05-2017, 04:16 AM
It is going to be stronger. Wide rings contain more weaker summer growth.

andrewpatrol
05-05-2017, 04:44 AM
Ask Dunc if he's got any idea of ring count in his Dragon planking. Pretty sure its DF. It's used everywhere in PNW of States for everything on a boat and I don't reckon they would've been too fussy.
If you search on here with google theres been threads before about this subject.
Laminated curved monocoque construction is going to be bl**dy strong anyway.
Maybe do a test of two different pieces with different counts suspended between supports?
Basically its down to how much patience and money you've got. I know where you can get better than 25 rings CVG on Monday buts its about 4 or 5 k per cube! Ive only ever seen reasonable ring count second hand DF once, usually its junk with knots.

PeterSibley
05-05-2017, 04:53 AM
Duncan's Dragon planking is quite high ring count.

wizbang 13
05-05-2017, 05:40 AM
I just tried to count off the rings on an inch of a particularly tight varnished and exposed deck plank on Woodwind. 40 something.
Old growth like that is lighter in weight.
Keep an eye out for bugs...tiny dust piles.
obviously no sap wood,(yes, some got into mine).
There can be substantial pockets of "sap" in the old wood, which will not glue, so watch for that also.
i recon you are on the right track Peter.
Gonna do a single layer of waste a bunch of time cold molding over?(oh I don't have a preference!)
bruce

PeterSibley
05-05-2017, 06:37 AM
G'day Bruce, probably the time wasting route, mainly cos I cut a few of my trees to get the wood to run into veneers , I visited a Fir importer yesterday, lovey Canadian fir ! Not cheap but I can buy clear material and that would save a lot of time cutting out knots and scarfing .

SMARTINSEN
05-05-2017, 07:08 AM
This was discussed not long ago, last couple of months ago. MNDave had input and I think there was a link to some of Smalser's old posts on the topic. Search is hard on the phone, if someone can find it before me please post the links.

andrewpatrol
05-05-2017, 07:11 AM
http://forum.woodenboat.com/showthread.php?5075-Ring-Count

this is a good thread from a few years ago Peter

as a rough guide to price 150x50 was costing me about 40/metre IIRC that was for CVG , very high count, green

SMARTINSEN
05-05-2017, 07:20 AM
orum.woodenboat.com/showthread.php?219555-Douglas-Fir-Again

Here is one, but ISTR that there is another very recent one.

PeterSibley
05-05-2017, 07:29 AM
Thanks Steve, I looked but couldn't find that thread.

Gib Etheridge
05-05-2017, 11:05 AM
Here's the thread Peter. It's about a specific piece of lumber.

http://forum.woodenboat.com/showthread.php?219555-Douglas-Fir-Again

Of course you already know that you want vertical grain, the closer to 90 degrees the better. Fir shrinks and swells quite a bit, so that's important.

10 rings is less than ideal, but you'll have to use what you can get. When you have a choice though pick the heavier boards, not heavier because they're damp, heavier because they're more dense. They'll be stronger, not that you'll need that, but they'll be more rot resistant as well.

Also, I think the cold molding is a good idea with all of the bugs where you are. If you put glass between the layers it should stop the boogers from getting any deeper into the planking than the compromised layer.

wizbang 13
05-05-2017, 11:14 AM
Hmmm. The nicest fir I ever used , old growth, was quite a bit lighter than any second growth I have used.

Gib Etheridge
05-05-2017, 11:47 AM
That very high ring count cream colored and lighter weight fir is lovely to work with, for sure, and it's the best looking by far, but the heavier the better so far as strength and rot resistance go, so long as it's got at least a pretty high ring count, 12-14/inch or more.

There are no really hard and fast rules though because there are too many variables from tree to tree. If it's wood you take your chances and hedge your bet as well as you can.

That's why yellow cedar came into being. ;)

Bruce Keefauver
05-05-2017, 04:18 PM
I just stumbled over this yesterday: WoodenBoat #224 Jagels Wood Tech column "The Fir with Wood like Larch". All sorts of interesting background info to the posted question. Basically Yes but...

PeterSibley
05-05-2017, 05:18 PM
I just stumbled over this yesterday: WoodenBoat #224 Jagels Wood Tech column "The Fir with Wood like Larch". All sorts of interesting background info to the posted question. Basically Yes but...

Thank you Bruce, I'll see if I have that issue.

Gib Etheridge
05-05-2017, 05:19 PM
Here it is. Scroll down to page 90.

https://www.scribd.com/document/293729386/WoodenBoat-224-JanFeb-2012

andrewpatrol
05-05-2017, 05:21 PM
Aren't you getting your wood treated anyway Peter

PeterSibley
05-05-2017, 05:36 PM
I'm having second thoughts Andrew, it would be very good for the life of the boat but would be far less pleasant to work with . I have't decided yet.

PeterSibley
05-05-2017, 05:45 PM
Here it is. Scroll down to page 90.

https://www.scribd.com/document/293729386/WoodenBoat-224-JanFeb-2012

Thanks Gib !!!