Does Saltwater preserve wood?

[Chris1956]

Some years ago, I visited the US Constitution. For those who do not know, she is the only wooden vessel still commissioned in the US Navy. The tour guide made a point to say the rain water rots out the ships timbers, and salt water preserves them.

 

[Philster]

Re: Does Saltwater preserve wood?

Rain water is 'sweet water' and is death to wood.

Salt tends to make life inconvenient for organisms that contribute to rot. Salt is a natural germ and small organism killer, and is just generally a good sanitizer.

But the old timbers were also treated and replaced over the years. I believe they were tarred or pitched. So, you get some treatment, plus salt, and it bodes much better for wood than fresh, sweet water.

There is much more science behind it, which would take into account the am't of UV exposure, the waters it sailed in, the timber density, etc.

For example, 'old growth' timber is much denser than what is harvested now. The timbers were already much more rot resistant from pulling minerals out of the rich soil for decades. Ya just don't get wood like that anymore. 'Old growth' lumber is the way to go. That's all they had back in the day.

For purposes of the tour, the guide provided good 'food for thought' information. Invariably, when this subject arises, someone (me sometimes, too) will remind others that old timbers are harvested from inland lakes/rivers and such and it's actually a thriving business -- this reclaimed, submerged wood is very valuable. It usually had 'something' going for it in terms of the exact type of water it sat submerged in and how it was actually preserving it because it was halting the rot. But rain water ain't got that 'something' going for it. Rain water bad.
.

 

[H20Rat]

Re: Does Saltwater preserve wood?

The other thing the guide may or may not have mentioned is the number of man hours and dollars required per year to preserve the ship... It isn't exactly self maintaining.

 

[tpenfield]

Re: Does Saltwater preserve wood?

Haven't the timbers and other wood on that ship been replaced piece-by-piece as they deteriorated over the years and only a few, if any, are 'original'?

Although there is a difference in the rate at which wood deterioration will set in on fresh versus salt water, it still deteriorates. . .

 

[Ned L]

Re: Does Saltwater preserve wood?

Yes, as Philster said, salt is a preservative. There is also a fairly narrow range of moisture content in which the fungus that causes 'rot' can live in. One of the reasons that timber can be 'salvaged' from lake bottoms is that it is in an anoxic environment (no oxygen). The organisms that cause the daecay can't live there.
As far as salt being a preservative, Charles W. Morgan (1841 whaling ship) at Mystic Seaport is currently undergoing a major rebuild and during the replanking of her bottom they are actually filling the voids between her planking and ceiling with a salt mixture to help perserve her. - Up to this rebuild something like 80% of her below-the-waterline structure was original. Now that's amazing!
Regarding Constitution, she has been re-topped, rebuilt, and restored so many times that... "The Naval History and Heritage Command Detachment Boston, the unit charged with overseeing Constitution’s maintenance and repair, estimates that 10 to 15 percent of the ship’s fabric is composed of timber installed between 1795 and 1797. This “original” wood includes the ship’s keel, lower futtocks, and the deadwood at the stem and stern."

 

[Home Cookin']

Re: Does Saltwater preserve wood?

for those thinknig about these ideas in the context of pleasure boats, there is also the factor of the hull being submerged all the time rather than exposed to air.

Also I'm under the impression that those boats leaked some. So if the bilge water was seawater, you get the reduced threat of rot from the inside. On the other hand, if the hull was 100% watertight and the accumulated water came from rain and condensation, you increase the threat.

Rot is but one enemy to the wood; in salt water there are wood-boring creatures as well.

Some of the older ships were clad in copper--and expensive but effective anti-fouling coating.

 

[hostage]

Re: Does Saltwater preserve wood?

Some of the best preserved wooden ships are preserved in fresh water in the great lakes. At the bottom it is very cold and it gets very little sun shine.

 

[Chris1956]

Re: Does Saltwater preserve wood?

I will bet there is little oxygen at the bottom of that Great lake as well.