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DavidF
02-04-2007, 06:09 PM
Things being what they are, I would rather cut down a black locust and air dry it so that I can use it for new floor timbers in my Folkboat.

How long will it take this wood to dry to a useable moisture content if I keep the lumber in my cellar (60 degrees with a dehumidifier).

Similarly, I am having some green tamarack planks (one inch thick) milled for replacement planking. How long before this dries to a useable level.

I know that boat lumber shouldn't dry down to kiln-dried levels. But what is good and how long should it take?

Thanks,
David

kc8pql
02-04-2007, 07:33 PM
The rule of thumb is one year per inch of thickness for hardwood. That will usually be about 12 to 14 % MC. Kiln dried lumber is 6% MC. Unless you live in a desert you'll never get it that low without a kiln. In fact, in time, kiln dried lumber stored in a barn or shed without temperature or humidity control will eventually equalize to about that same 12 of 14 %.

Cuyahoga Chuck
02-04-2007, 07:47 PM
Don't know where you are but here in the Great Lakes all habitations have central heating which drives the indoor humidity down to desert levels in winter and may cause wood to dry too fast.

kc8pql
02-04-2007, 07:52 PM
Good point. The year per inch is for lumber stacked outside under cover. Inside temp and humidity could take it much lower faster. That's why KD is used for furniture.

Mrleft8
02-04-2007, 08:30 PM
Don't store it inside if yer using it for boat lumber. By the time you get around to using it, it'll be ready.

Bob Smalser
02-04-2007, 08:38 PM
Locust has been transplanted to a range of around 1000 X 3000 miles, so that's not much help in guessing what kind of climate we're speaking of. Green Tamarack however, says New England or NE, as we call it larch out here. So assuming the NE states above NYC:

Stack and sticker fully-green stock outdoors where it belongs in airflow and natural humidity for at least 4 months, then you can hasten the drying using fans and dehumidifiers, although by then it'll be June and will dry faster outdoors where you originally stacked it. Leave it in a heated basement without airflow and it will mold, dehumidifier or not....and add airflow and it will dry too fast.

Locust can be used for timbers as soon as the moisture content in the center of the stock drops to below 20%, although it will continue to shrink some until it stabilizes at 12-15%. It will stabilize at the rate of one May-October drying season per inch of thickness, so if your 4/4 stock is milled in February, it will reach 12-15% by late October, but you can use it at 20% sometime in July. As bending stock where some shrinkage won't affect fit, you can use it green.

Your Tamarack will dry faster, but planking stock benefits from being dead at or even a bit drier than equilibrium to be sure it swells a tad when the boat hits the water. Depends on whether you need to plane the roughsawn stock...some mills cut smooth enough to avoid the planer....but have the wood milled to the minimum thickness you require. 1" stock won't be at equilibrium until probably September. Half-inch stock by late July. Maybe slightly faster, maybe slightly slower. Borrow a good moisture meter to be sure.

Here's how to seal endgrain and make stacks. Tamarack will be relatively forgiving and for 1" stock you can get by with bearers every 3-4' and no sealer. Locust won't be forgiving at all, and you'll need bearers every 2', endgrain sealer, and lots of weight on the top in the form of concrete blocks:

http://www.woodenboatvb.com/vbulletin/upload/showthread.php?t=499

http://pic3.picturetrail.com/VOL12/1104763/4110272/52876879.jpg

http://pic20.picturetrail.com/VOL12/1104763/4110272/147680135.jpg

few3
02-04-2007, 08:43 PM
Black Locust is an SOB when it comes to seasoning. It has longer dry time than white oak in my experience. It also likes to move all over the place ( buckle, twist ). In your basement would be great, but without the dehumidifier. Try to mill as true as possible, and coat the snot out of the ends will wax or what have you.

boylesboats
02-04-2007, 11:46 PM
Things being what they are, I would rather cut down a black locust and air dry it so that I can use it for new floor timbers in my Folkboat.

How long will it take this wood to dry to a useable moisture content if I keep the lumber in my cellar (60 degrees with a dehumidifier).

Similarly, I am having some green tamarack planks (one inch thick) milled for replacement planking. How long before this dries to a useable level.

I know that boat lumber shouldn't dry down to kiln-dried levels. But what is good and how long should it take?

Thanks,
David

In the cellar?:eek: It will never dry in the cellar... You open air shed to dry lumber, it will take two years to dry good and well...I got a PDF file on drying wood if you need it...

DavidF
02-05-2007, 05:25 AM
My boat came with the name Patience. I guess this is why. I'm eager to get going but turns out I need sit around for a long time watching wood dry.
I thought about the cellar (a furnished walk-out cellar) because it is heated but not kept very warm so it might hasten my wait.
But I want to do this right so I guess I will wait.
Thanks for the replies.

few3
02-05-2007, 06:15 PM
You are looking for the wood to reach an equilibrium as far as moisture content goes. If the celllar swings wildly or is 90% humidity, it may not be the best place. Outdoors, as Mr. Smalser shows, is ideal, but if you lack outdoor space or understanding neighbors, then a cellar is better than inside. However, When I am seasoning large timbers of white oak, 8/4 and larger, I prefer humid areas for drying, at the very least, and let them sit for.........actually, two years now.

Vika
02-07-2007, 01:21 PM
In the cellar?:eek: It will never dry in the cellar... You open air shed to dry lumber, it will take two years to dry good and well...I got a PDF file on drying wood if you need it...

Could you possibly share that PDF file with me?

Chan
02-07-2007, 06:02 PM
Can somebody tell me why exactly kiln dried lumber should not be used in boatbuilding?

Bob Smalser
02-07-2007, 07:30 PM
Can somebody tell me why exactly kiln dried lumber should not be used in boatbuilding?

It's used every day in boatbuilding. All that expensive mahogany and teak was severely kilned. Big mills simply don't ship without kilning, or their wood gets full of beetle larvae, and wood for epoxy boats must be at 12% EMC or lower, which makes kilning mandatory in most climates.

Much kilned stock is too dry to bend well however, and requires rehydration. There is also a good chance some of the kilned stock is overcooked and will never bend well. The lightest trip through kilns is KD-19 or 19% EMC for framing stock and outdoor wood. That's your best bet of you must buy kilned stock.

Nanoose
02-07-2007, 09:45 PM
OK...a similar, but different question...

We need a new mast. The old one is a 30-32' long tree. We'll probably just get another tree.

We were told to shape it green - to not dry it first. Why?

Bruce Hooke
02-07-2007, 09:52 PM
One reason I can think of is purely practical...it will take a number of years for a solid timber big enough for a mast to dry...

Nanoose
02-07-2007, 11:11 PM
One reason I can think of is purely practical...it will take a number of years for a solid timber big enough for a mast to dry...

One person told us of a local kiln to take care of that

kc8pql
02-07-2007, 11:29 PM
I would think trying to kiln dry a tree would result in some pretty impressive cracks.

Bob Smalser
02-08-2007, 12:46 AM
We need a new mast. The old one is a 30-32' long tree. We'll probably just get another tree.

We were told to shape it green - to not dry it first. Why?

Wood shrinks tangential to the growth rings twice as much as it does radial to the growth rings. When left in the round, you can exactly measure the different levels of shrinkage in the width of the cracks once the wood fully stabilizes with the air and humidity.

It will eventually crack some anyway, but if I were using a tree for a mast, I'd do everything possible to slow, not speed up its drying. You have a much better chance of the cracks being smaller and spread out rather than one big one that affects the timber's structure.

Nanoose
02-08-2007, 12:19 PM
Thanks, Bob.

Chan
02-08-2007, 02:51 PM
So Bob.
Is all of the doug fir commercially available kiln dried?

Bob Smalser
02-08-2007, 03:12 PM
So Bob.
Is all of the doug fir commercially available kiln dried?

Yes.

For something else, you have to special order it.

Thorne
02-08-2007, 05:53 PM
Ooooh -- this is turning into an "Ask Bob" thread!

;0 )

On the topic of tree masts, didn't the 17th -> early 19th navy store spars / spar material in saltwater ponds? They may not have had to do it here in the US (where all the big trees came from for many years), but I've seen the ponds at old naval yards in the UK.

Would these masts have been used "wet and green", or pulled out and dried before work began on shaping them?

dmede
02-08-2007, 06:28 PM
Yes.

For something else, you have to special order it.

I have found one location here in the Bay Area that actually sells what they are calling "green" DF. Mintons in Mtn. View. They are mostly big timbers, 6x6, 6x8 and up. and all look to have moslty low ring counts, but I haven't really looked to hard since none of them are small enough for me to handle on my own.