Depth of Water At Site of Collision

[Dennis Smith]

Hi All,

I have just been reading the statements of Capt. Rostron in the American Enquiry - Off the Titanic Explorer Set. During his questioning he was asked the depth of water Titanic had sunk into.

His reply was - Quote "2000 and odd fathoms of water where Titanic sank". He then states that "He looked at his chart".
Fine, if this was a modern day enquiry, we would all accept this as fact (ish), because we have the technology to measure these depths. How did they do it then?? By my calculations 2000 fathoms comes out at approx 2.3 MILES, how the hell did the cartographers of the time work out such figures - even if they were (A bit) wrong. Surely it wasn't just pure guestimation (SP).

Did they use a form of the "Sounding Machine", surely not, over 2 miles of cable supporting its own weight and thin enough to be wound on to a machine and still support its weight?

Parks or anyone give me clue!!

Best Wishes and Rgds

Dennis

 

[Dave Gittins]

Dennis, they simply sounded with an awfully long sounding line. Working in such depths was no novelty by 1912, thanks to the needs of the telegraph companies. Some of their deeds are quite amazing. They routinely fished out broken cables and repaired them, having first found the cable with nothing better than celestial navigation and dead reckoning.

I'd add a proviso. The soundings in great depths were not very close or numerous. As a seafarer, you've correctly anticipated some of the problems of sounding. Add the joys of North Atlantic weather and the surveyor's lot was not a happy one.

 

[Bob Godfrey]

40 years before Titanic, British survey vessels like the Challenger had sounded depths down to 5 miles in the area of the 'Challenger Deep' (Marianas Trench). They also were equipped to trawl for samples of bottom sediments and marine life at depths far greater than Titanic's resting place - as Dave said, very like the process of trawling a grappling hook to locate telegraph cables. Here is an excerpt from a contemporary account of the recovery of a broken transatlantic cable from a depth of 2.5 miles in 1866:

"When the Albany left Heart's Content, Captain Moriarty went in her. He had been in the Great Eastern the year before and saw where the cable went down, and had had his eye on the spot ever since. He claimed, with Captain Anderson, that he could go straight to it and place the ship within half a mile of where it went down. At this old sailors shook their heads, and said ... "No man could come within two or three miles of any given place in the ocean." Yet the result proved the exactness of his observations. With unerring eye he went straight to the spot, and set his buoys as exactly as a fisherman sets his nets ... When it was first proposed to drag the bottom of the Atlantic for a cable lost in waters two and a half miles deep, the project was so daring that it seemed almost impious - a war of the Titans upon the gods. Yet never was any thing undertaken less in the spirit of reckless desperation. The cable was recovered, as a city is taken by siege - by slow approaches, and the sure and inevitable result of mathematical calculation. Every point was studied beforehand - the position of the broken end, the depth of the ocean, the length of rope needed to reach the bottom, and the strength required to lift the enormous weight. To find the place was a simple question of nautical astronomy - a calculation of latitude and longitude. It seemed providential that, when the cable broke on the second of August, 1865, it was a few minutes after noon; the sun was shining brightly, and they had just taken a perfect observation. This made it much easier to go back to the place again. The waters were very deep, but that they could touch bottom, and even grapple the cable, was proved by the experiments of the year before. But could any power be applied which should lift it without breaking, and bring it safely on board? This was a simple question of mechanics. Prof Thomson had made a calculation that in raising the cable from a depth of two and a half miles, there would be about ten miles of its length suspended in the water. Of course, it was a very nice matter to graduate the strain so as not to break the cable. For this it had been suggested that two or three ships should grapple it at once, and lifting it together, ease the strain on any one point - a method that we shall see was finally adopted with success".

Had any serious attempt been made back in 1912 to locate the wreck of Titanic, this remained the only available method. On which note, a passage from that 1866 account comes to mind: The 'fishing-tackle' is on a gigantic scale. The hooks, or grapnels, are huge weapons armed with teeth, like Titanic harpoons to be plunged into this submarine monster."

 

[Dennis Smith]

Cheers for the info guys, much appreciated.

God, I'm an idiot for not remembering about the grappling for Marine Cables, I even did an essay on it when I was in college.- DOH!!

Thanks anyway guys

Best Wishes and Rgds

Dennis

 

[Keith R E Hall]

the depth of where titanic sank is about 3778 meters (2.5 miles). Water pressure at that depth is about 3.5 tonnes per square inch.

 

[Paul Lee]

Haven't you noticed how the water pressure has changed over the years

In 1986, we were told it was 2 tons to the square inch. Then, for a Channel 4 (UK) documentary c.1996, it was three tons p.s.i, then a few years later it was 3.5 tons p.s.i.

Cheers

Paul

 

[Keith R E Hall]

I suppose that when the tide changes this may effect the water pressure at that depth. It probably changes so slightly that it may be barely noticeable. But why don't they raise this vessel before the rusticles destroy it completely in 20 years time it could be too late.

 

[Keith R E Hall]

by the way i don't think that any such machine exists that could lift a weight greater than 30,000 tonnes.

 

[Michael H. Standart]

>>But why don't they raise this vessel before the rusticles destroy it completely in 20 years time it could be too late.<<

Because as you pointed out, no such machinary and tooling exists to do the job, but also because there would be absolutely no point in doing so. Salvage is a risky and expensive business. One I've heard referred to sarcastically...and accurately...as a good way to turn a large fortune into a small one. The value of the Titanic's hull is that of scrap and she could be used for little else as her condition makes any sort of restoration out of the question. Nobody is going to go to pony up several hundered billion dollars of cash for a few hundred thousand dollars worth of scrap metal.

 

[Bill Wormstedt]

Keep in mind the trouble they had bringing up 'the Big Piece' a few years ago - which was a small fraction of the size and weight of the wreck itself. And also didn't contain thousands of tons of water, either.

 

[Michael H. Standart]

No kidding! It took two expeditions to get the thing up and they still almost lost it on the second attempt.

 

[Keith R E Hall]

Was that a hull section that was raised or something else.

 

[Bill Wormstedt]

Yes, part of the hull. 30 or 40 tons, I recall? A bit taller than one deck of the ship, as I recall, and the outside wall of a C Deck cabin.

 

[Michael H. Standart]

I thought it was twenty tons, but no matter. The whole thing consisted of the shell plating along with the portholes and with the frames still attatched. The way it was brought up was by attaching lift bags filled with diesel fuel and letting them do the work. It was rather slow going and the beast turned out to be heavier then they expected.

I don't think it helped matters that the seas were on the rough and ready side when they tried to bring it aboard the first time. When I saw that heavy nylon line starting to stretch and smoke, I knew they were in trouble. Lines started parting and thank whatever diety you believe in nobody was in the way. Those things have been known to cut people in half.

They were wise to let it go the first time, work things out and go back for it on the next expedition.

 

[Keith R E Hall]

Boom cables have also been known do do a similar thing. One person i know had a lucky escape when he was struck on the hand by a high tension cable it took of 3 and a half of his fingers all he has left is half a finger and a thumb it even cut through the railing he was holding on to at the time.