by Peter Maas
This time Baker carefully passed the cable outside the descending line and brought it to the ring in the center of the after torpedo-room hatch. Then he ran into more difficulty. Lying almost prone on the deck, Baker suddenly got the idea that the shackle pin, instead of being in the shackle itself, was hanging from it on a chain. His breath audibly faster as he vainly groped for the pin, his faceplate began to fog. He had enough presence of mind to stand up and open his exhaust valve one turn to clear his helmet. Then Baker took another look at the shackle, finally saw the pin and started laughing at himself.
A worried Momsen was promptly on the phone wanting to know what was wrong. “Baker,” he demanded, “are you OK?”
“I am OK,” Baker said. “Don’t take me up. I know what I am doing. It’s hard to explain. It’s just that the pin is in the shackle exactly where you showed me it was.” A minute afterward he reported, “Down-haul wire fast to hatch.”
Everything was now ready for the momentous fifth trip of the rescue chamber. Bill Badders was in command, his assistant was John Mihalowski. It was a descent unlike any of the others. Both men knew that they were putting their lives on the line. Momsen went over the procedure with them. He told them that the chamber would not be able to make its usual watertight seal against the hatch. They had to act on the assumption that the after torpedo room was flooded. Therefore the pressure in there would be at least equal to that of the surrounding sea and possibly greater if it was topped off by a pocket of highly compressed, trapped air inside the sub. Instead of the atmospheric environment maintained in the chamber’s upper compartment during the previous four dives, the pressure would have to be built up after settling on the submarine to match the expected thrust of air and water. All they could depend on to hold them to the hatch were the chamber’s bolts. The slightest error in judgment would drown them instantly. And there was something else as hideous to think about. Once the chamber itself was pressurized, there was no way to exhaust the carbon dioxide the men would be exhaling. They would have to move swiftly to find out if there were any more survivors. Anything over twenty minutes, Momsen warned them, would be exceedingly dangerous. If they were overcome, there was nothing he could do to save them.
As Badders and Mihalowski started down, the initial phase of the operation was the same as in earlier trips—flooding main ballast and blowing the lower compartment. Then with the chamber linked to the Squalus by the down-haul cable alone, the air pressure in the upper compartment was steadily increased until it corresponded to the crush of the North Atlantic outside. Badders opened the hatch to the lower compartment and, ankle-deep in the water that always remained, he bolted the chamber to the Squalus. A minute later Mihalowski, manning the pressure valves in the upper compartment, reported that Badders was preparing to crack the after torpedo-room hatch.
He was doing it as gingerly as he could. But suddenly a rush of air exploded past Badders into the chamber. Right after it came the sea surging rapidly around his legs. “More pressure!” he shouted to Mihalowski. His partner reacted instantly. The sea hesitated, then fell back. Badders dropped to his knees and eased the hatch back until he was able to peer under it. But all he could see, level with the hatch opening, was water. The after torpedo room was completely flooded.
As Mihalowski relayed the news, Momsen sensed the woozy tone in his voice. The two men had been under extreme pressure for seventeen minutes. “Close the hatch,” he ordered. “Come up.”
SWEDE MOMSEN’S WORK was far from over. The Squalus had to be raised and returned to Portsmouth to try to determine what had occurred to send her to the bottom on the morning of May 23.
Ugly reports were already sweeping the country that sabotage had been responsible for the disaster. These rumors were spurred by Al Prien’s statement, during a press interview of some of the surviving crewmen, that he was not only positive he had closed the main induction but that he had checked the control board and “none of the lights there showed there was any trouble.” Then the Chicago Tribune broke a story that there was a massive investigation for possible espionage in all Navy yards engaged in warship construction.
It got so bad that Captain Amsden was forced to declare, “Despite certain stories in the press, there is no evidence at this time to substantiate any rumor of carelessness or sabotage . . . the yard is spy-proof.” Whatever good this did was lost when Amsden bowed to the demands of cameramen that Prien at least be allowed to pose for pictures the day after he made his statement. As the photographers clicked away at Prien, a reporter suddenly tried to interview him again. “I told you,” the jittery Amsden shouted, “that Prien was not to be questioned! Do you want to get me court-martialed?”
Of far more concern to the Navy were the valves themselves. Although the consensus was that the big outlet leading to the engine rooms was to blame, it remained supposition at best. And even if it was so, was there some built-in defect? They had to find out. A sister submarine in the new class was due to be commissioned at Portsmouth in a few days, another would slide down the ways within a month, still more were in the works. Grief-stricken Captain Greenlee, as yard manager, put it as well as anyone could. “No one knows what really happened,” he said, “because no one has gotten down there to see. Anything about the valves is mere conjecture. The cause of the disaster will not be known until the vessel has been examined in dry dock.”
To get her there, everything depended on Momsen and his divers. It would be an unparalleled salvage operation with the Squalus—310 feet long, 1,450 tons—lying inert on the ocean floor, her hull partially buried in mud and clay 243 feet down and fifteen miles of open sea to be traversed before she could be brought home. The statistics were staggering enough. But beyond them, in the ensuing struggle, the submarine would seem almost to become a living thing with a baleful, sometimes raging will all her own.
At first Momsen privately doubted that it was possible to salvage her. And without the helium and oxygen mixtures developed under his leadership while he was in charge of the experimental diving unit in Washington, it would have been hopeless. But fate had again placed him in the right spot at exactly the right moment. He had assumed command of the unit just twenty months earlier, in the fall of 1937. The move, as he then put it, was “most gratifying.” It was an understatement. After the exhilarating experience of training personnel to use the lung and the rescue chamber at each of the Navy’s major submarine commands, Momsen had languished aboard the heavy cruiser Augusta, flagship of the U.S. Asiatic Fleet—a tour of duty marked chiefly by heavy social demands for his expertise in playing the ukulele.
Until Momsen, the depth a diver could go to, the length of his stay there and the work he was capable of doing were all severely inhibited because he was fed ordinary air, which, although we often don’t think of it as such, is actually a gas mixture consisting roughly of eighty percent nitrogen and twenty percent oxygen. For a diver the culprit in this combination is the nitrogen.
If he comes up too rapidly after a descent, he will be stricken by the bends. The name comes from the tortured shapes into which it can twist its victims. When a man is subjected to great pressure, not all the nitrogen he breathes in his air supply can be exhaled. Some of it, instead, is carried by the blood into his body tissues in much the same manner that carbon dioxide is forced into carbonated drinks. As long as the pressure is decreased slowly, the nitrogen exits as innocently as it entered. But if the pressure is lowered too fast, it forms a froth of bubbles like a bottle of ginger ale that has suddenly been uncapped. These bubbles tend to concentrate at the bone joints. The pain even in a mild attack is excruciating. In a severe case the bubbles clog the veins completely and can cause instant death from heart embolism.
Still more insidious during a deep dive is the way nitrogen attacks the central nervous system and drastically affects neuromuscular coordination. Eventually, along with a carbon dioxide buildup inside his helmet, it knocks him out.
The problem that confronted Momsen and his dedic
ated medical team was to come up with some substitute for nitrogen or find some means to counter its action so that a diver could go deeper than ever before, remain alert throughout his mission and return as speedily as possible to the surface.
Oxygen, which does not bubble up in the bloodstream during decompression, seemed an ideal answer to the bends. But under pressure, its toxicity causes a diver’s lips to begin to tremble, his eyelids to flutter. Within seconds he is blind and in the grip of terrible epilepticlike convulsions.
Helium, which is found almost exclusively in the United States, first attracted attention in 1925 as possibly useful for deep-sea diving. The Navy even looked into its potential for a while, but the project, not very extensive, fizzled out. Under Momsen the investigation was revived in earnest. The earlier experiments had indicated that helium might be an improvement over the high nitrogen content in air. On the other hand, it had been demonstrated that it was no panacea. A diver could get the bends just as badly, if not worse, from a helium and oxygen mixture as from air. So, with Doctors Behnke and Yarbrough working tirelessly at his side, Momsen strove to piece together a definitive picture of helium’s impact on diving physiology.
From the beginning it was tough, tedious, often disheartening going, especially in terms of decompression. The big pressure tank at the Washington Navy Yard became a daily chamber of horrors as diver after diver suffered the bends. The name of the game was the educated guess, an intuitive insight, endless trial and error. As with Momsen’s previous underwater research, there was practically nothing to fall back on. Until then, the most notable testing in this area had been conducted by the British, who tried a blend of half helium and half nitrogen, along with enough oxygen to support life. The theory was that the two gases would act independently of each other after entering the body. If this were so, the decompression schedule could be keyed to either the helium or the nitrogen, thus halving the time required to bring a diver up. When nothing of the sort happened, the British concluded that there was no point in using helium for deep diving. “Had they,” Momsen noted in his log, “pursued their inquiry and tried helium with oxygen alone, they would have discovered its real value, that of clear and comfortable thinking under pressure.”
Still, before he could demonstrate this, all kinds of pitfalls lay ahead. In his tenacious odyssey through the mysterious forces that affect man beneath the surface of the sea, Momsen even attempted a variation on the British theme. Divers were given a helium and oxygen mix for twenty minutes and then were switched to air for another twenty minutes. The hope was that the helium, which is considerably lighter than nitrogen and has a much higher diffusion rate, would be eliminated from the diver’s body during the time air was being administered to him. Hence only the nitrogen in the air had to be taken into account in his decompression. If it worked, it would mean that a diver could stay down for hours alternating between helium and oxygen and air with a decompression period for just the final twenty minutes he was on air. But it didn’t work. The bends always followed.
Momsen refused to give up. For months other approaches were painstakingly explored—without success. The testing, however, was not a complete waste. In the end he became convinced that no matter how many gases were juggled around to create a breathing mixture with oxygen, they all had to be taken into consideration in decompression. Out of this he settled on his fundamental proposition: First, to use helium to the maximum advantage, only helium and oxygen should be fed to a diver on the bottom. Second, to keep the amount of helium absorbed in his body to a minimum, the percentage of oxygen must be as great as possible.
A simple experiment dramatically showed the superiority of this combination over air deep in the sea. A yeoman attached to the unit was placed under pressure at a simulated depth of 200 feet with his typewriter. He was first given air for five minutes while he copied a standard typing exercise. Next he repeated the exercise for five more minutes on helium and oxygen to see what effect it would have on his coordination of mind and muscle. Momsen was a bit jolted when the yeoman said that he was sure he had done better on air. Quite the opposite, in fact, was true. Breathing air under pressure had lulled him into a false sense of security that drastically impaired his judgment. While breathing helium and oxygen, however, he was much more alert and knew exactly when he had struck a wrong key. The number of words he had copied in each instance was about the same, but he had made three times as many mistakes, even skipping entire lines, on air without being aware of it.
Once this had been established, Momsen focused on finding a way to bring up a diver safely and speedily from great depths to the surface. Every attempt to shorten the decompression time again resulted in divers being viciously afflicted by the bends. Finally he returned to the old rates of ascent used for a diver who had been on air. But to his consternation it didn’t seem to make much difference. There was still an alarming number of men who developed the bends and it was becoming a serious morale problem. Obsessed by an unknown factor that suddenly threatened to wreck the whole project, his medical people as mystified as he was, Momsen angrily headed each night’s computations in his notebook: “What the hell am I doing wrong? What does helium do that nitrogen doesn’t?”
He awoke early one morning with the answer. A diver on air starts his long, dreary ascent with comparatively brief decompression stops that increase in duration as he nears the surface. The trouble, Momsen was sure, must be at the first stop. Helium, with its high diffusion rate, rushed out of a diver’s body tissues so much faster than nitrogen that his bloodstream did not have time enough to cope with the load, and bubbles formed, which brought on the bends. By fixing the initial stop of a man coming up after a helium and oxygen dive at never less than seven minutes, the incidence of bends at once dropped almost to zero.
This was capped by another breakthrough that spectacularly cut the time a decompressing diver had to remain in the water. In an exhaustive study of human tolerance to oxygen under pressure, Dr. Behnke had discovered that shifting a man to pure oxygen once he reached fifty feet and was past its toxic stage not only prevented bubbles from forming but actually hastened the elimination of excess helium in his system. This meant that a diver after his first stop could be raised fairly quickly to fifty feet. Next, instead of letting him dangle in the sea at that point, he would be hauled directly to the surface, hustled into a recompression chamber, and fed pure oxygen at a pressure equal to the fifty-foot depth he had just left.
A great deal of work remained—all the calculations, as complex as they were vital, to establish new physiological diving norms, to plot the limits of human endurance, to determine the most efficient helium and oxygen ratios. But it had become a matter of refinement. There were no more blind alleys to follow or seemingly impossible hurdles to leap.
Divers could forget the old nostrums—always eat an apple prior to a dive, eat nothing at all the day of a dive, don’t drink liquor the day before a dive—that they used to ward off the bends. With the simulated descent of Badders and McDonald to 500 feet—the limit of the pressure tank—deep-sea diving was put on a rational footing never before achieved.
It also caused the first major innovations in diving dress, which had stayed essentially the same during the hundred years since a German-born inventor named Augustus Siebe devised his prototype suit. Divers on air often suffered terribly from the cold. Helium, however, was far worse. Body heat dissipated so rapidly that a water temperature of about sixty degrees was all a man could endure for very long. Yet in the depths opened up by helium and oxygen, freezing temperatures would be commonplace. Momsen took his problem to a New York manufacturer who was turning out electrically heated clothing for pilots flying at high altitudes. The result was special underwear with wired pads sandwiched between two layers of wool. But with so much oxygen involved, Momsen also wanted protection against the ghastly possibility of fire and he had just received a new batch of the electric long Johns with the wiring wrapped in glass thread insulation.
These same depths made the buildup of carbon dioxide more dangerous than ever. While carbon dioxide in small doses isn’t particularly harmful on the surface, its effect increases in proportion to the depth, finally triggering a cruel process of asphyxiation that divers call “the chokes.” The kind of open ventilation system in which an endless supply of air can be sent down to a diver and expelled into the sea was out of the question since a synthetic blend like helium and oxygen could be stored only in limited quantities aboard ship. This led Momsen to the creation of the “helium hat.” Unlike air helmets, it formed a single unit with a diver’s breastplate to prevent gas leakage. Inside, it featured an ingenious recirculating device that sucked the helium and oxygen through a container of CO2 absorbent and then forced it back into the main supply line. Although the helium hat was still in the experimental stage when the Squalus went down, its development was far enough along to show it was capable of reducing by eighty percent the amount of helium and oxygen that would otherwise be required.
So in a scant twenty months the art of diving deep into the sea, all its concepts and potential, had been completely revolutionized. “Suddenly,” Momsen wrote at the time, “we have actually projected the depth at which man may work efficiently and safely to 500 feet and theoretically to a thousand feet, bringing within human grasp more than a million square miles of the earth’s surface with an incredible storehouse of natural treasures as yet untouched. It is just the beginning. Surely the day must come when man will lay claim to vast expanses of what we call the high seas.”
But now, without warning, instead of Momsen spending the summer of 1939 off Portsmouth proving out his controlled laboratory work, all of it—the helium hat, the heated diving suits, the use of oxygen in decompression, the whole development of the new breathing mixture as a substitute for air—faced a crucial test.