I was watching a piece on TV about a ship which sank in the sixteenth century. It sank to the bottom of the sea and its remains were retrieved in the 20th Century.
This was a wooden ship. It was made of bits of dried tree, sliced into planks and joined up. They probably used nails, and it may have had some ballast to stabilise it - but how could all that wood suddenly sink?
I have sailed in wooden dinghys, and sometimes they turned over if we did something stupid while racing. We got wet, but they stayed afloat and the only problem was righting them and bailing the water out. We didn’t have to raise them from the bottom of the lake.
I can see how wood might get waterlogged, and a bit uncomfortable to sit on. The ship might even tip over, and lie on its side with the mast and sails in the water. But surely it should float near the top of the water, not sink to the bottom like a metal ship. Using wood that floats seems intuitive, if you build a thing that is meant to sit on top of water.
And yet countless ships seem to have gone to Davy Jones’s locker over the millennia. Is it due to their cargo, ballast or other onboard weight? Can someone explain?
I don’t remember which. The passing ship, full of drunks with a drunk captain, was in no way maintained. The tar/rope/caulk gave way one night en masse and the waterlogged vessel broke apart and sank straight away with all hands and without a sound (as all aboard were passed out).
Sorry, it’s fiction, I know. It got stuck in my head long ago and your post dragged it up fro the depths.
GHO57 - Thank you for the link. I hunted before I asked but did not see it.
I’m not sure that the point was clearly answered, and some of the comments were off point. However, the implication is that the weight of the cargo and/or ballast outweighs the flotation ability of the wood, as I suggested.
Which implies the ship should rise back to the surface, if it breaks up and loses its ballast. or stay afloat if its cargo is thrown overboard. Yet you don’t hear of large numbers floating after they were holed. They all seemed to sink sooner or later.
Or do we only hear of the total wrecks, while many ships just bobbed around and were actually salvaged ?
The link is useful, but I don’t think we have the full story yet.
The dense hardwoods used in shipbuilding aren’t that buoyant. Oak, for example, has a specific gravity ranging between 0.6 and 0.9 depending on the particular piece of wood. Live oak is even denser, around 0.95 in some cases. I’d hazard that shipbuilders would use denser, sturdier pieces of lumber in many cases. So already the wood in the ship isn’t super buoyant. After you add some metal nails, various other hardware, stuff in as much pitch as possible to seal the joints, and keep that wood damp, it’s conceivable that many fragments of a ship would actually sink if you gave them the chance (even ignoring cargo and ballast).
Wood floats. Or rather, most woods float when dry. Here’s some specific gravities. Seawater has a SG of about 1030. So any wood with a lower value will float.
The denser the material, the harder the wood… and usually ships were built from densest materials available; they needed to withstand a lot of pounding from the ocean. Top end oak, at 930 would float with 90% of its mass underwater… so if there’s something else… like ballast, cargo, cannons, nails, paint, ropes, anchors, sails, metal supports… in order to make the ship unsinkable they couldn’t mass more than 10% of the weight of the hull. In reality… ships carry way more than 10% of their own weight in cargo.
I saw an episode of Dirty Jobs some time ago in which SCUBA divers were salvaging lumber that had settled at the bottom of a lake. These were basically debarked/debranched tree trunks that had sunk on their own - no pitch, no screws, no cargo - demonstrating that it’s possible for wood to be (or become) denser than water. This might explain why old shipwrecks remain on the bottom even after the hull has fallen apart so completely that it has no structural integrity at all.
One reason that wood is less dense than water is that it contains tiny pockets of air. The densities listed are for dried wood. When soaked with water, the wood begins to approach the density of water, perhaps exceeding it. Wood also contains resins and other lighter than water than substances that may be displaced by water as well.
When the Mary Rose sank, it was full of cannons etc. and went down like a stone. When it hit the sea floor, it got jammed in the mud pretty good. That held it down long enough for the wood to get saturated and therefore more dense than seawater.
Hell, post a picture. She was one of my first loves. Unfortunately, she was also already dead by that time. Damn, gotta’ go watch West Side Story before my girlfriend comes home…
Yes, it’s my thread and I think we have resolved my query.
I have travelled to your time from the middle of the last century*, and back then Natalie Wood was a young man’s dream. The plastic creatures found today are simply boring, and don’t look natural.
So, please proceed, so long as it is accompanied by illustrative and educational pictures - focusing on important swimwear issues where appropriate.
*I am disappointed, because when I passed through the 50s and 60s, the people of those times told me that you folk in the 21st century would all have flying cars and cheap space travel. You have disappointed me
