SUBMARINE RISKS

Wairarapa Times-Age, 27 June 1939, Page 6

SUBMARINE RISKS

WHV RESCUE WORK IS SLOW TIME AND SEA DEFEAT EFFORTS. TREMENDOUS NATURAL DIFFICULTIES. Defeated by time and the sea and human inability to succour them. 125 men have lost their lives in two submarine disasters within a fortnight, and the belief that apparatus capable of overcoming the tremendous natural difficulties involved in rescue work had at last been devised has been sadly shaken, wrote a special correspondent of the “Sydney Morning Herald.” The losses of U.S.S. Squalus and H.M.S.' Thetis have again brought into tragic prominence a problem of the sea which defies human ingenuity to master it, and is likely to continue to defy it for many years to come. The apparatus used on the Squalus —a metal chamber large enough to carry eight men and designed to fit on to an escape lock of a sunken vessel —was remarkably successful, the rescues by its means crowning more than a decade of intensive research conducted by American experts since the loss of the U.S.S. S 4 in 1927, when 40 men perished. But even this wonderful device has not fully solved the problem. THE TIME FACTOR. As with the men of the Thetis, the men of the S 4 were virtually buried alive—they died from suffocation when the air in their iron prison gave out, not from drowning. They perished miserably hoping against hope that rescuers working outside would upset precedent and save them in time. For the time factor is the most important of all. Simply, the problem of submarine rescue work is this. There is only a limited quantity of air in a sunken craft—in the case of the Thetis there was enough to last 36 hours—and a rescue must be effected before that supply is used up. The almost insuperable difficulties presented by sea pressure at great depths, however, make rapid work impossible. It often takes many hours to locate a sunken submarine, even when, like the Thetis, it is equipped with an emergency buoy, containing a telephone, which can be released and sent to the surface.

Again divers cannot go down to the submarine immediately because they must gradually adapt themselves to increasing sea pressure as they submerge, and to lessening pressure as they come up. Any other procedure would be fatal.

Further, two or three days may be required, even in ideal weather, to get cables under the wreck and lift it bodily to the surface. Even longer time may elapse if difficulties arise while tunnels for the cables are being cut under the wreck by water jets of great power. There are delays and obstacles all along the line. It is significant that no submarine has ever been raised from the seabed in less than two days and a-half—-not even one which was deliberately sunk in relatively shallow water, and which was equipped with numerous experimental devices. RIVAL DEVICES. Although the ingenious steel chamber used for the Squalus rescues has given promise of being a wonderful life-saver, its success can hardly be complete. Its rise and fall In deep water must be slow, so that the occupants can become accustomed to changing pressure. Even if it could have been used on the Thetis, at least 25 men would have remained on board the submarine by the time supplies of air had given out. If there had been only 50 men oh the Thetis, the air supply would have lasted twice as long, and would have given a rescue chamber,' had the British Navy possessed one, a chance of saving most of the men.

The Davis emergency device, which enabled four men to escape from the Thetis, was first used successfully by four men on board H.M.S. Poseidon, which sank off Wei-Hai-Wei in 1931. The apparatus does give a prospect of security to individual members of submarine crews, but it does not eliminate the possibility of fatal risk for each man using it. Two other men who escaped from the Poseidon by using the Davis apparatus died soon afterwards. They went immediately to the surface, and the sudden change in pressure—from 501 b to the square inch to ordinary atmospheric pressure—killed them. Moreover, because of the circumstances in which it must be used, the Davis device cannot enable more than a few to escape from a sunken submarine which may contain many men. The Davis device consists of nose clips to keep water out of the nostrils. goggles, and a rubber bag containing a cylinder of compressed oxygen. A group of men are equipped with the appliances, and crowd under the hatch. There would not be room for more than a dozen at the most. r lhe compartment is then flooded until it is practically full of water. This is done to equalise the pressure within and without the submarine, otherwise it would be impossible to open the hatch. The hatch is opened, and as many men as possible escape to the surface. The difficulty is that there is not room under the hatch for more than a few men when the compartment has been almost filled with water.