How dry does cedar need to be?


dan mulholland
 


In the way more than you want to know department, for the skin on frame Shenandoah I'm attempting, I wanted to find a clear, full dimension(al) red cedar 2X4, 6' long, for the oars- they'll be 7' long with blades.  Cruising Craigslist, there was an ad for cedar; I texted them; they said they'd cut a few in the morning.  I went to the hills west of Creswell and got four of them, 8' long.  Logs are from the Holiday Farm fire.   The have some bug damage in them; wanted to assure myself I'd get what I wanted.  I went out the next day and got two 2X6 by 8's, to be really sure, and there are other uses, and it wasn't that expensive at $12.50 a board.  

So, when could I use this fresh cut material?  Concerned about moisture content. Bought a cheap h-f moisture meter- this tells you your board is dry on the surface, pretty much.  Thanks to Mr. Internet,  I found a table with western red cedar KG per cu meter weight, both average green and after kiln drying (12% water).  Did some calculations to convert to pounds and inches, calculated the cu inches of the boards, and weighed Pamela holding each board, subtracting Pamela from the calculations....  The bottom of the table has the results.  So, it appears that the boards are still pretty wet, but not as wet as green, so progress has been made.  Have them in the basement with a dehumidifier and fan going, "sticked", ends painted.    I'll check progress in a week.  Hope it doesn't take two years.  Maybe I can speed it up by watching it dry out. 

Ready for my professional engineering license.

Dan



David Graybeal
 

I would not use undried Western Red Cedar for something where Staying Straight was critical... like an oar. Too likely to move, and even a little movement can severely impact the functionality of an oar.


Jove Lachman-Curl
 

Hey Dan,
I think they'll dry out quicker than you'd expect.
The old "year per inch" rule is for firewood, hardwood, outdoors covered, and has a big safety factor. Birch firewood stored fresh cut outside in spring can dry in 2 months.
Indoors with circulation and thinner sections, I bet you'll be down to 15% in a week or 2.
Apart from some experience, I've found my information in "understanding wood" which is a great book, And "the bowers bible" which has some info on drying green wood bows, carving them rough, then finishing them once dry. If you just weigh it every few days, you'll see it stop getting dryer.

I have got my clear cedar for kayak and greenland style paddles from Jerries, they sell clear 4x4s in the outdoor area for fencing. They are exceptionally nice and clear and are ~$20 each. I look through the pile and take the nicest one or two.
I have one  or two, dry in my garage from couple years..... if your process doesn't work out, let me know and i'll sell you one.
I don't need them right now, so I can just go get another when I do.
-Jove


On Wed, Jan 13, 2021 at 10:11 AM David Graybeal via groups.io <harbordavid=yahoo.com@groups.io> wrote:
I would not use undried Western Red Cedar for something where Staying Straight was critical... like an oar. Too likely to move, and even a little movement can severely impact the functionality of an oar.


David Graybeal
 

Actually, the 'year per inch' standard is for air-drying stacked and stickered lumber. Not firewood. And air-drying wrc WILL go a bit quicker than that. As a species it does tend to dry quicker than denser woods. But from Fresh Cut to Oar Stock? Months. Many months.


Jove Lachman-Curl
 

Well, in that case, I do still have those 4x4s if you need them Dan. Perhaps you've factored the time in.
I'll be interested to hear how long it takes to reach equilibrium weight.

This document is an interesting skim.

On Wed, Jan 13, 2021 at 10:36 AM David Graybeal via groups.io <harbordavid=yahoo.com@groups.io> wrote:
Actually, the 'year per inch' standard is for air-drying stacked and stickered lumber. Not firewood. And air-drying wrc WILL go a bit quicker than that. As a species it does tend to dry quicker than denser woods. But from Fresh Cut to Oar Stock? Months. Many months.


Richard Green
 


The spruce oars I used on Passage were ten feet long.  They were actually a bit short for the 7’ beam, 4500 lb boat but I loved the weight compared to length and, clear spruce, they never caused me any issues in ten years.  Tiller between my knees, I rowed Passage fairly often in windless times.  Sometimes in the dark of the evening I’d row Passage around the west basin at Astoria or into anchor position or off anchor.  Worked great….’course I was a bit younger then.

Rich



dan mulholland
 

Jove,

Appreciate the offer.  I'm not yet in a hurry, and one of the 2X6's is pretty close.   Will keep you posted, it's so exciting, like watching paint dry.   Of course, I never checked at Jerry's or other lumber yards, assumed the cedar was all knotty  stuff.

Some of these boards, including the 2X6's, have the grain lineup I'd prefer, too.  "flat" as compared to vertical.

Dan


Stephen Miller
 

Mr Plywood in Portland usually has a good selection of clear wood.  Its my go to place for CVG fir. 

Steve Miller

On Wed, Jan 13, 2021, 5:10 PM dan mulholland <mulhollanddr@...> wrote:
Jove,

Appreciate the offer.  I'm not yet in a hurry, and one of the 2X6's is pretty close.   Will keep you posted, it's so exciting, like watching paint dry.   Of course, I never checked at Jerry's or other lumber yards, assumed the cedar was all knotty  stuff.

Some of these boards, including the 2X6's, have the grain lineup I'd prefer, too.  "flat" as compared to vertical.

Dan


Gerard Mittelstaedt
 

Just wondering - is Cedar strong enough to make a satisfactory oar ?
Presuming loom dimension is as thin as many oars I know of.

- Gerard Mittelstaedt --- living in a place where Cedar fence boards I
know of are not very strong.

On Wed, Jan 13, 2021 at 7:15 PM Stephen Miller <w7srmsteve@gmail.com> wrote:

Mr Plywood in Portland usually has a good selection of clear wood. Its my go to place for CVG fir.

Steve Miller

On Wed, Jan 13, 2021, 5:10 PM dan mulholland <mulhollanddr@hotmail.com> wrote:

Jove,

Appreciate the offer. I'm not yet in a hurry, and one of the 2X6's is pretty close. Will keep you posted, it's so exciting, like watching paint dry. Of course, I never checked at Jerry's or other lumber yards, assumed the cedar was all knotty stuff.

Some of these boards, including the 2X6's, have the grain lineup I'd prefer, too. "flat" as compared to vertical.

Dan
--
Gerard Mittelstaedt -- mittel48@gmail.com
McAllen, Texas
USA


David Graybeal
 

Yes most cedars, even including WRC, are strong enough for an oar. WRC is not ideal - as it is both weaker than the more common alternatives (Sitka Spruce, Douglas Fir) AND a bit less limber/more brash. Alaska Yellow Cedar is better, among the cedars... but that wasn't the question.


Jove Lachman-Curl
 

There is a mill out in Jasper that specializes in yellow cedar, I got to tour it once when my company was looking at one of the guys' buildings.
west winds Forest products. The guy usually sells by the train car, so might not sell to the small guy, but he loves to see his wood get used for pretty things, so might be a conversation for the right project.
-Jove

On Thu, Jan 14, 2021 at 8:54 PM David Graybeal via groups.io <harbordavid=yahoo.com@groups.io> wrote:
Yes most cedars, even including WRC, are strong enough for an oar. WRC is not ideal - as it is both weaker than the more common alternatives (Sitka Spruce, Douglas Fir) AND a bit less limber/more brash. Alaska Yellow Cedar is better, among the cedars... but that wasn't the question.


dan mulholland
 

Of course there are differing opinions about red cedar and oars.   I'm following the instructions from the Gaco oarlocks guy, John Murray:

The shaft is fitted to the Gaco oarlock to hold the blade vertically to the water. Leather or rubber protectors are not necessary for the oar with the Gaco and the increased resulting diameter at the rowlock aids stiffness and strength.
www.gacooarlocks.com
He ranks red cedar at the top, above spruce and the others.   That's because he's avoided the weakness issue by having the oar quite thick at the oarlock, including a fiberglass/epoxy wrap there.  This also makes it so it won't crush.  After that, red cedar has great strength for how much it weighs.   When properly seasoned, of course.  If you look at the rowboat I had when I was young, it was a cedar, strip planked boat.  When dry, it was not too heavy, though the seams opened way up.  After being in the water for a while, the leaks stopped, and the boat was quite a bit heavier.





Dan


Richard Green
 

Yeah, I didn’t address the cedar question either but I loved my spruce oars.

Rich




On Jan 14, 2021, at 8:54 PM, David Graybeal via groups.io <harbordavid@...> wrote:

Yes most cedars, even including WRC, are strong enough for an oar. WRC is not ideal - as it is both weaker than the more common alternatives (Sitka Spruce, Douglas Fir) AND a bit less limber/more brash. Alaska Yellow Cedar is better, among the cedars... but that wasn't the question.


David Graybeal
 

I'll have to disagree with your Mr. Murray. One three primary counts. 

First - cedar is weaker than spruce -- MoE (which doesn't tell us everything about strength is a very good first appoximation) is 7.66 GPz vs. 11.03 And the strength to weight ration, contrary to his claim, is not nearly as good as spruce - which is one of the best.

Second - one desirable characteristic of an oar is 'spring or snap'. When you pull on an oar, it will flex and store some energy which it releases at the end of your stroke. There's probably and engineering # for this somewhere, but I don't know what it is. I can tell you that cedar has less than spruce.

Third - dentability -- they're both softish. But cedar much more so.  Janka is 350# for cedar & 510# for the spruce. Varnishing a soft oar can create the 'eggshell effect', where an impact can fracture the hard film because it's so lightly supported by the soft substrate. Which allows moisture to intrude and compromise the finish. It's true that adding a fiberglass/epoxy wrap at the vulnerable oarlock location is one way around that... it's a compromise. I don't like it for a variety of reasons.

 

On the plus side - the wrc IS far more rot-resistant than the spruce. Dramatically so. Since oars tend to be dry-stored.... that's not a huge issue. And keeping the finish up will further obviate the issue. And cedar is light, which is an advantage. But so is spruce.

 

Hope that's helpful...


Jove Lachman-Curl
 

Dan, that is a beautiful pic of your old row boat. And I bet those oars will be great, I'm sure we're all eager to see what you build.
Graco free oar plans look very promising.
https://www.gacooarlocks.com/plans-for-making-oars.pdf

Ok.....now we're delving into material science., i'm hooked. I've been fascinated by wood choices since I was a kid.

Weaker, yes, but steel is stronger, and I wouldn't make an oar out of steel. Perhaps what you'll want to look at is Specific strength (as in per unit mass), for that I'm sure you'll find spruce and cedar almost identical, spruce being stronger in proportion to it being denser.

Snap and spring back, in engineering we call this the coefficient of restitution, damping capacity or loss factor. It is the % energy returned vs absorbed during flexing. You can get a sense of this by tapping an object and hearing how long it takes to deaden.
You will find that softwoods are more efficient than hardwoods in this regard generally. Carbon fiber being better than wood. This is why smaller aircraft propellers are often still wood, or wood core with carbon wrap, so they are less inclined to resonate and vibrate. And why machine tools like mills and lathes are built of cast iron not steel. I doubt there is an appreciable difference between spruce and WRC. But I'm curious that you say there is, I'd like to know more? Cedar is certainly more brittle in my experience.
I bet there is an optimal oar flex you'd want in an oar though. Totally stiff oars can be hard to row with, and I bet limp flexy oars are equally annoying. Here are some numbers for that.
https://www.concept2.com/oars/oar-options/shafts/stiffness
A good example for materials perspective is Archery arrows, that have been successful in many woods from Ash to birch to cedar, aluminum to carbon. All just by varying the ID/OD and so on.

Dentability..... a function mainly of density. I'd love to see a table of wood characteristics normalized for density. Styrofoam is very dentable, but makes a good core for a carbon or glass shell structure.
At the rowing club I used to go to, the old coach used an old pair of Stemfli hollow loom spruce oars, and a cedar racing shell which I think was stampfli also.

Rot resistance.... i totally agree.

One idea would be to bond on a carbon or glass tape down the tension side of the loom. This would strengthen and stiffen them greatly. But maybe it's not traditional at all.
I'd recommend SollerComposites for that, they've been great value and service for me.

I found this old PDF on aircraft woods. it shows that when normalized for density, spruce does have a 3% flexural strength advantage over WRC. and a 7% stiffness advantage.
However, with the larger diameter the looms in WRC they may be as stiff or stiffer for the same weight.
   https://ir.library.oregonstate.edu/downloads/2r36v361c
image.png
-Jove

On Fri, Jan 15, 2021 at 12:21 PM David Graybeal via groups.io <harbordavid=yahoo.com@groups.io> wrote:

I'll have to disagree with your Mr. Murray. One three primary counts. 

First - cedar is weaker than spruce -- MoE (which doesn't tell us everything about strength is a very good first appoximation) is 7.66 GPz vs. 11.03 And the strength to weight ration, contrary to his claim, is not nearly as good as spruce - which is one of the best.

Second - one desirable characteristic of an oar is 'spring or snap'. When you pull on an oar, it will flex and store some energy which it releases at the end of your stroke. There's probably and engineering # for this somewhere, but I don't know what it is. I can tell you that cedar has less than spruce.

Third - dentability -- they're both softish. But cedar much more so.  Janka is 350# for cedar & 510# for the spruce. Varnishing a soft oar can create the 'eggshell effect', where an impact can fracture the hard film because it's so lightly supported by the soft substrate. Which allows moisture to intrude and compromise the finish. It's true that adding a fiberglass/epoxy wrap at the vulnerable oarlock location is one way around that... it's a compromise. I don't like it for a variety of reasons.

 

On the plus side - the wrc IS far more rot-resistant than the spruce. Dramatically so. Since oars tend to be dry-stored.... that's not a huge issue. And keeping the finish up will further obviate the issue. And cedar is light, which is an advantage. But so is spruce.

 

Hope that's helpful...


 

They've got a Web page now:

https://www.westwindfp.com/

On 1/15/2021 12:13 AM, Jove wrote:
There is a mill out in Jasper that specializes in yellow cedar, I got to tour it once when my company was looking at one of the guys' buildings.
west winds Forest products. The guy usually sells by the train car, so might not sell to the small guy, but he loves to see his wood get used for pretty things, so might be a conversation for the right project.
--
John <jkohnen@boat-links.com>
Anyone who believes exponential growth can go on forever in a finite world is either a madman or an economist. (Economist Kenneth Boulding)
--
This email has been checked for viruses by AVG.
https://www.avg.com


Richard Green
 

Of the available cedars, Alaskan Yellow Cedar would be my choice.  

Cedar has all those numerical this and that’s but cedar will much more easily split than spruce, it doesn’t like the wetting/drying cycle in my experience.  You can help with that by having, and would want anyway, a hardwood tip of mebbe two inches laminated across the grain so when you hit a rock or dock the hardwood end will take the punishment whereas the cedar may well split, cross grain or flat grain notwithstanding.  IMHO

Rich

On Jan 15, 2021, at 1:54 PM, Jove Lachman-Curl <jovelc87@...> wrote:

Dan, that is a beautiful pic of your old row boat. And I bet those oars will be great, I'm sure we're all eager to see what you build.
Graco free oar plans look very promising.
https://www.gacooarlocks.com/plans-for-making-oars.pdf

Ok.....now we're delving into material science., i'm hooked. I've been fascinated by wood choices since I was a kid.

Weaker, yes, but steel is stronger, and I wouldn't make an oar out of steel. Perhaps what you'll want to look at is Specific strength (as in per unit mass), for that I'm sure you'll find spruce and cedar almost identical, spruce being stronger in proportion to it being denser.

Snap and spring back, in engineering we call this the coefficient of restitution, damping capacity or loss factor. It is the % energy returned vs absorbed during flexing. You can get a sense of this by tapping an object and hearing how long it takes to deaden.
You will find that softwoods are more efficient than hardwoods in this regard generally. Carbon fiber being better than wood. This is why smaller aircraft propellers are often still wood, or wood core with carbon wrap, so they are less inclined to resonate and vibrate. And why machine tools like mills and lathes are built of cast iron not steel. I doubt there is an appreciable difference between spruce and WRC. But I'm curious that you say there is, I'd like to know more? Cedar is certainly more brittle in my experience.
I bet there is an optimal oar flex you'd want in an oar though. Totally stiff oars can be hard to row with, and I bet limp flexy oars are equally annoying. Here are some numbers for that.
https://www.concept2.com/oars/oar-options/shafts/stiffness
A good example for materials perspective is Archery arrows, that have been successful in many woods from Ash to birch to cedar, aluminum to carbon. All just by varying the ID/OD and so on.

Dentability..... a function mainly of density. I'd love to see a table of wood characteristics normalized for density. Styrofoam is very dentable, but makes a good core for a carbon or glass shell structure.
At the rowing club I used to go to, the old coach used an old pair of Stemfli hollow loom spruce oars, and a cedar racing shell which I think was stampfli also.

Rot resistance.... i totally agree.

One idea would be to bond on a carbon or glass tape down the tension side of the loom. This would strengthen and stiffen them greatly. But maybe it's not traditional at all.
I'd recommend SollerComposites for that, they've been great value and service for me.

I found this old PDF on aircraft woods. it shows that when normalized for density, spruce does have a 3% flexural strength advantage over WRC. and a 7% stiffness advantage.
However, with the larger diameter the looms in WRC they may be as stiff or stiffer for the same weight.
   https://ir.library.oregonstate.edu/downloads/2r36v361c
<image.png>
-Jove

On Fri, Jan 15, 2021 at 12:21 PM David Graybeal via groups.io <harbordavid=yahoo.com@groups.io> wrote:

I'll have to disagree with your Mr. Murray. One three primary counts. 

First - cedar is weaker than spruce -- MoE (which doesn't tell us everything about strength is a very good first appoximation) is 7.66 GPz vs. 11.03 And the strength to weight ration, contrary to his claim, is not nearly as good as spruce - which is one of the best.

Second - one desirable characteristic of an oar is 'spring or snap'. When you pull on an oar, it will flex and store some energy which it releases at the end of your stroke. There's probably and engineering # for this somewhere, but I don't know what it is. I can tell you that cedar has less than spruce.

Third - dentability -- they're both softish. But cedar much more so.  Janka is 350# for cedar & 510# for the spruce. Varnishing a soft oar can create the 'eggshell effect', where an impact can fracture the hard film because it's so lightly supported by the soft substrate. Which allows moisture to intrude and compromise the finish. It's true that adding a fiberglass/epoxy wrap at the vulnerable oarlock location is one way around that... it's a compromise. I don't like it for a variety of reasons.

 

On the plus side - the wrc IS far more rot-resistant than the spruce. Dramatically so. Since oars tend to be dry-stored.... that's not a huge issue. And keeping the finish up will further obviate the issue. And cedar is light, which is an advantage. But so is spruce.

 

Hope that's helpful...