|DIVING FOR MILLIONS OF SUNKEN GOLD:
Salvaging the "Laurentic's" Cargo
From the Fireman's Fund Record, August 1924.
The SS Laurentic, bound for America with a cargo of bar gold valued at $21,500,000, sank January 25, 1917, off the north coast of Ireland and lies in 120 feet of water. The sinking was caused by either mines or torpedoes. The salvage work has been carried on for the past seven years, and of the total number of 3211 bars of gold aboard the ship, 3057 have been recovered to date. The following article taken in part from Lloyd's List and Shipping Gazette Weekly Summary, concerning the salvage of the Laurentic's cargo of gold, gives some idea of the day's work of the deep-sea diver.
The equipment of the diver appears exceedingly cumbersome but the weight is almost neutralized by the high water pressure and the diver is allowed comparative freedom of movement. The connection with the ship above is composed of an air pipe, life line and telephone wire which are bound together as a unit. The telephone is absolutely necessary, due to the fact that the diver directs all operations with regard to hoisting and is virtually the eyes of the crew above. One mistaken signal may mean loss of life and the accomplishment of many months.
Air is supplied the diver from a compressed air tank maintained at 100 pounds by a steam compressor. At the depth of 120 feet the diver is breathing air at 55 pounds pressure. He descends to the bottom rapidly, his system adjusting itself to the increased pressure in about one minute. Upon reaching bottom he works at top speed for thirty minutes, when he receives orders to come up. The return to the surface requires much more care than the descent. The diver glides to a point thirty feet from the surface, remains there five minutes, comes up a further ten feet, waits there ten minutes more, and then is called up to his last halt, merely ten feet below the surface, where he has a quarter of an hour to wait before coming aboard the ship.
Unless the diver is in excellent physical condition, he may develop compressed air illness in spite of all precautions. This condition is caused by coming out of the water too quickly into the decreased pressure of the air above. Since there is a difference of forty pounds pressure per square inch between the working level and the surface, the lungs and circulatory system must adjust themselves again to meet this change. As the rapidity of adjustment is not uniform for all individuals, compressed air illness often develops in the individuals who adjust themselves more slowly. The means of alleviation for these cases is afforded by the recompression chamber, the diver being placed in a chamber which is maintained above normal air pressure. The pressure is gradually decreased to normal at intervals suited to the case. Due to the exhausting effects of work under pressure the diver can go down but twice each day.
Each diver has a sack, into the mouth of which a steel scoop is fastened. In this he places all objects which he desires to take up and places the sack in a bucket, which is lowered for that purpose.
Wave motion is a factor of considerable danger to the diver. A short, choppy sea, although disagreeable upon the surface, has no effect below about fifteen feet, while a free ocean swell has a powerful effect upon the bottom, picking the diver up and sweeping him about like a helpless puppet. The distance between wave crests governs the depth to which their force is operative, the longer swells exerting force to a greater depth. Since a sunken ship is often on its side, the swells may lift one side free of the bottom one moment and let it fall back the next. If the ship has settled on a rocky bottom, the breaking up process may be carried on at a rapid rate.
The mud which had settled in the wreck presented an obstacle which was not easily overcome. Nothing can be shoveled under water, for the debris is washed off as soon as the shovel is moved. A suction pump was tried, but was ineffective, due to the depth of water. Finally a fire hose with a stout branch pipe at the end was let down and turned on the mud with good results. As the mud was loosened and washed away the diver felt of the heavier remaining objects for those having the characteristic weight and dimensions of a bar of gold.
The work of salvaging the Laurentic has been slow and at times rather discouraging. During the years of 1920 and 1921 a quarter of the wreck was taken apart, plate by plate, and during the entire period only fifty-two bars of gold were salved. Although there are only 154 bars still on the wreck, their value is $1,000,000.00, which makes one more effort worth while.
[Fireman's Fund Archives: 4-1-3-4-35; 0406.]
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