Edward Beach - Around the World Submerged

Having put enough air into the tanks to stop the descent, it was apparent that the ship would now rise. As she rose, however, the size of the air bubble increased as the sea pressure reduced; and as the air bubble increased in size, it pushed even more water out through the bottom of the ballast tanks, thus making Triton still lighter. In this condition, we would continue to lighten and rise faster until we reached the surface.

Once, during the war, with the old Trigger leaking badly and surrounded by Japanese destroyers listening for us to start our pumps, we had survived just such a situation by putting an air bubble in one of our tanks and then either venting it slowly into the ship (we dared not use the main vents, which would have loosed a betraying bubble of air to the surface) or blowing it carefully. With the desperate skill of emergency, for fifteen hours Johnny Shepherd maintained precise control of our depth, as the accumulated leakage of water gradually made us heavier and heavier, until finally we outlasted the enemy. We had not dared to relieve Johnny.

The situation here was far less tense. There was no enemy; we could afford to let air bubbles come to the surface. Our only problem was to control the size of the bubble in our tanks to keep from broaching surface on the one hand or going too deep on the other.

As Triton ballooned upward, I watched silently for signs of the required action. It is for situations like this that men are qualified in submarines. With approval, I saw Rauch keeping his eyes on Harris, his hand already resting lightly on the controls for the main vents. Thamm was watching, too. Triton rose at an ever-increasing pace and finally Dick gave the order: “Open main vents.”

I could hear the vent mechanism operating and all of us heard the rush of the entrapped air as it escaped from the tank. But Dick was still watching the depth gauges, “Shut main vents,” he ordered. His objective was to catch some of the air still inside the tanks in order to retain some of the resulting buoyancy. In the meantime, with approval, I noted that he had not ordered Rauch to stop the trim pump, that we were still pumping water from the midships auxiliary tanks to sea.

Triton’ s rise toward the surface ceased rather abruptly. By this time, we had no forward motion through the water at all. With the ship badly out of trim, she was controllable in depth only by the constant buoyancy of her great hull, plus the variable buoyancy of the expanding and contracting volume of air in the ballast tanks. Undersea ballooning was an apt simile.

But Dick had let out too much air, for Triton was now heavy and began to sink once more; as she sank, the air bubble remaining in the ballast tanks would be further and further compressed, with the result that the ship’s buoyancy would continue to reduce and she would now progressively descend faster and faster—though slower than the first time. Dick was ready for this, however, and after we had sunk some little distance, he again ordered that tanks be blown, but for a considerably shorter time than before. Again, Triton halted her descent and began to rise; and, as she neared the surface, Dick opened the ballast tank vents and allowed most of the air to escape.

In the meantime, we had continued pumping water out of the ship. Gradually, our wild gyrations lessened as we got her correctly trimmed. With ballast tanks again full of water, no air trapped in them, Triton finally hovered, motionless, balanced precariously with her internal weight exactly equal to that of the water displaced.

It might be well to explain at this point a fact that submariners know well, but which may not be so well known to others: it is impossible for a submerged body to be so delicately trimmed or balanced that it will remain indefinitely static, neither rising nor falling. Despite fanciful tales written by people who do not know their physics, things cannot just sink part way. A submerged submarine has no reserve buoyancy; that is to say, she gains no additional buoyancy by sinking a little deeper in the water (a surface ship, passing from more-dense to less-dense water, increases imperceptibly in draft). If an eight-thousand-ton submarine is one pound heavier than the water she displaces, she will slowly sink. The deeper she goes, the greater the pressure; even the strongest hull will be slightly compressed, thus reducing the volume of displaced water and increasing the disparity between her weight and that of the water displaced. She will go all the way down until she reaches the bottom. Conversely, a submerged submarine one ounce light will ultimately broach the surface. The only exception to this rule occurs when there is a layer, or stratum, of heavier water underlying a lighter layer. In this case, the submarine can “balance” on the boundary between the two, as long as the dissimilarity continues to exist. This is known as “riding a layer.”

It is true that a submarine almost in perfect trim—as near to perfect trim as it can possibly get—might very very slowly sink in water of a certain density until it reaches a layer of water considerably cooler or more saline than the one for which trimmed, and there she will stay for a while. Ships have been known to ride thus, suspended between two layers of water of dissimilar densities, for many hours. There have even been stories about balancing a submarine so skillfully that the slight increase in displacement gained by raising a periscope would cause her slowly to drift toward the surface, and sink slowly when the periscope is withdrawn inside its bearings, but, practically speaking, such situations are rare and highly temporary.

The submarine riding on a layer will maintain depth so long as all the factors affecting her equilibrium remain exactly the same. But they never do. Considering the many changes constantly taking place in the weight of the submarine, due to leakage through propeller shaft glands, to name one unstoppable source, or water taken in by the evaporators, for instance, it is certain that within a short time the sub’s trim will change. In all cases, the change is in the direction of becoming heavier and, without the intelligent hand of man, she will shortly resume her descent. Nothing, in other words, can float without control between the surface of the sea and the bottom.

Davy Jones might have been perturbed had he observed Triton, the world’s greatest submarine, slither to a halt and commence a series of astonishing gyrations in depth, accompanied by a frenetic blowing and venting of air and grinding of pumps. He would indeed have been justified in suspecting something to have gone seriously wrong. Such was, however, far from the fact. We were well pleased with the results of our drill, which showed that we had more than adequate control of our huge ship, even under the hazardous conditions which result from a complete loss of power; and after a short time, the mock-casualty restored, Triton’s great propellers began to turn purposefully once more and she settled down on her course to the northwest at a speed faster than any submarine had ever traversed these waters.

According to Triton’s Log, it was next day, at about ten-thirty at night, when a calamity of very real proportions confronted us. Intimation of the problem came when Don Fears called me on the ship’s service telephone in my room. For a few days we had had a severe leak around the starboard propeller shaft, which had been growing steadily worse. Now, as Don put it, it was no longer incidental, but of some magnitude. Fears and Curt Shellman were both in the lower level of the engine room, and I got there as soon as possible.

Spotting the leak was easy. Great sheets of water were spurting out around the periphery of the flange and gland through which the propeller shaft passed into the sea, driving a solid white spray perpendicularly outward from the shaft itself around 360° of its circumference, soaking the overhead of the platform deck above, the curved side of the ship outboard of the shaft, and the tiny walk deck. A heavy canvas dropcloth had already been rigged to protect the machinery near the leak, while Curt Shellman and three of his engineers, all of them drenched, were struggling perilously close to the rapidly revolving propeller shaft in their effort to stem the flow of water.