Submerged softwood?

Christopher Tidy snipped-for-privacy@gmail.com on Tue, 11 Aug 2020

Generally water soaked wood will sink. It may take a while, but some does.

OTOH, some doesn't and I have seen logging rafts left "too long" which have plants growing on/in them.

Hi folks,

I know this isn't quite metalwork, but is it a shop-related question and nothing to do with politics, so here goes...

If you take a piece of light softwood, such as pine or fir, and keep it submerged under water for a really long time - months or years - does it eventually absorb enough water so that it no longer floats?

Anyone know? I am assuming that the wood is not coated or treated, but my question refers to the behaviour of the wood before decay takes place.

Thanks!

Chris ======================

Thanks for the lumber pond tip and link. That's a good story there!

So wooden ships only continue to float after years because the planks expand and stop the interior of the hull filling with water, even if the individual planks would sink on their own?

Chris

All ships "float" because the amount of water that they displace equals the gross weight of the ship :-)

In Lake Washington, there's some old-growth logs that basically DID sink; a few that are near shore have a few percent of wood above the water, The area was logged, and the lake used for transport, around 1900.

I'm told that Salt Lake had some rail trestle timbers recovered in recent decades, that hadn't rotted.

Some species, yes. Cypress and pine.

Christopher Tidy snipped-for-privacy@gmail.com on Tue, 11 Aug 2020

Ships float because they displace more water than they weigh. And no matter how tight those edges are, wooden boats leak. which is why there are so many ways to make the hull water tight, starting with packing the seams and on to tarring the bottoms.

if you fill a wooden boat with rocks and let the water in, it will sink. You can then dive down and remove the rocks and the boat will float. Assuming the wood isn't so water logged (or dense) that it won't float. I remember something about building the railroad through the Amazon Jungle. The main engineer would just cut down trees, if the logs sank he'd fish them out and use that wood for ties. Another instance where "exotic woods" were used for mundane purposes because there was lots of it and it was the only wood around.

Can you remember where you heard that story? I'd like to read more about it.

Thanks!

Anyone know which species of lumber sank on the North American log drives? Looking at the black-and-white pictures, the bark looks like some kind of pine, but it's hard to be sure.

Chris

Thanks for the lumber pond tip and link. That's a good story there!

So wooden ships only continue to float after years because the planks expand and stop the interior of the hull filling with water, even if the individual planks would sink on their own?

Chris

================================================

The classic definition of a ship is "a hole in the water into which you pour money."

Even very old iron ships stay afloat if you pour in enough money

Some species, yes. Cypress and pine. ====================================== Oak survives for centuries under water:

Yeah, softwoods will become waterlogged and sink. If they sink into cold oxygen free water of the right PH they will not rot. Even if the bark is on the tree. In Lake Washington, for example, there are a lot of trees that slid into the lake as they rode a huge landslide. If I remember correctly the landslide occurred about a 1000 years ago and was cause by a really big earthquake. The trees are owned by the state. About 25 0r 30 years ago, I think it was, a fellow was pulling these trees up in the dead of night because the old growth timber is so valuable. I think the trees were hoisted onto a barge. Anyway, he got busted. Ah, here's a link:

Christopher Tidy snipped-for-privacy@gmail.com on Wed, 12 Aug 2020

Depends on where the logging occurred. Lake Washington (Seattle) is "full" of Fir trees. East of the Cascades it is pines. So what sank was what was local.

Christopher Tidy snipped-for-privacy@gmail.com on Wed, 12 Aug 2020

No. Sorry, One of those side digressions in an article about something else entirely.

"Jim Wilkins" snipped-for-privacy@gmail.com on Wed, 12 Aug 2020 06:40:29

-0400 typed in rec.crafts.metalworking the following:

And the prototype of an aircraft will fly once the weight of the paperwork exceeds the Gross Take-off Weight.

I've been thinking about this topic for a week or two, and I was curious, so I submerged a block of softwood (pine, I think, but perhaps fir) in a tank of writing ink for 8 days.

Today I split the block of wood open with a chisel to see how far the ink had penetrated into the wood. Something like 3 to 6 millimetres parallel to the grain, but only a fraction of a millimetre perpendicular to the grain. The ink also soaks much deeper into the dark rings (summer growth, perhaps - does anyone know?) where the wood is more porous.

Here are some eye-candy pictures of my experiment for the wood fans to enjoy...

Chris

It depends on how the wood cells break down after felling which depends on the species and conditions. I don't know about soft woods but hard wood such as oak varies a lot with English and European oak being durable outdoors and American white oak but American red oak has cell walls which break down readily and allow the wood to be permeated easily which results in a short life outdoors, I have seen it mentioned that you can blow smoke through a red oak plank end to end due to this, one wood worker I know said 3-4 years for red oak outdoors and it's staring to show rot, I have an English oak fence post at the boundary of my property which is about 70 years old and while degraded is still largely solid.

Likely white pine

Christopher Tidy snipped-for-privacy@gmail.com on Wed, 12 Aug 2020

Cool. Now, what's your conditions?

Ack, my geek side emerges, "To Do A Proper Test!" 1) Compare a block free floating in the ink with the grain parallel to the surface, to one free floating with the grain perpendicular. 2) another set floating against a "stop" of some sort, partially submerged. 3) another set held completely under, but this spins off further experiments where the factor would be how deep the ink is, to gauge the effects of pressure on the penetration. Of course, comparisons could/should also be made of the moisture content of the wood before and after. And track the temperature of the ink solution as well as air pressure.

Then repeat for different species of wood (pine, fir, oak, poplar, etc.)

Hmmm, sounds like the sort of thing one could get a grant for the experiment in a Forestry Graduate program, or Engineering. After all, is that not important information for such processes as "pressure treating lumber"? _Permeability of solutions in processed select lumber species._

enjoy

pyotr