Why the Best Technology for Escaping from a Submarine Is No Technology

A small, hand-propelled German submarine, the Brandtaucher, sank in 1851 in sixty feet of water, with her captain, Wilhelm Bauer, and two crew-members aboard. Her hull immediately began to collapse under the pressure of the sea. Captain Bauer, who had built the tiny craft, knew that if he could keep his two companions from panicking while allowing the water to rise steadily inside her, the interior and exterior pressure would equalize and they would be able to open the hatch and get out. They did. As Bauer wrote later, “We came to the surface like bubbles in a glass of champagne.”

The world made little note of this first escape from a sunken submarine; in fact, most naval authorities did not yet even take submarines seriously. But the demise of the Brandtaucher held a lesson that would be offered—and go unheeded—time and again during the next century. At depths of up to three hundred feet, escape from a disabled submarine was and is possible simply by getting out into the water unassisted and exhaling while rising naturallv to the surface.

While this often-demonstrated fact went ignored, a virtual industry grew up for the invention, manufacture, and distribution of complicated devices to be used in submarine escape. None worked any better than the simple technique of unaided escape; most didn’t work as well. The story of these devices is the story of a dependence on technological solutions where none was necessary and a resulting absolute blindness to a nontechnological alternative that was in many ways preferable.

The first primitive, hand-propelled submarines had been constructed in the 1700s. By 1886 the French were building undersea vessels in large numbers. In the United States the first government contract to build a submarine was awarded in 1895, and six more were ordered in 1900. By the beginning of World War I, France had 45 submarines, Britain 77, Russia 28, the United States 35, and Germany 29. All of them were designed for shallow coastal waters, and none could stay submerged for more than a few hours.

As submarines developed, so did the search for some form of artificial breathing apparatus to be used while awaiting rescue after sinking, or as an aid in escape. The historian Elting E. Morison once pointed out that “a machine, any machine, if left to itself, tends to establish its own conditions, to create its own environment and draw men into it.” That is precisely what these escape devices did.

The first successful escape system, the German Dräger breathing set, of 1911, established an approach that would govern the direction of research for fifty years. Researchers in the United States and Britain were not far behind in developing similar systems. In England it was the Davis Submerged Escape Apparatus, or DSEA; in the United States, the Navy produced the Momsen Lung.

Developed by Lt. C. B. Momsen, the mechanical lung was a masterly adaptation of earlier, more cumbersome diving apparatus. It began as a relatively simple device, consisting of an arrangement of tubes attached to a gas-mask-like rubber mouthpiece that acted as a conduit for inhaled and exhaled air. A system of valves in the mouthpiece directed the flow of exhaled air from the mouth into a foot-square breathing bag; there it was enriched with oxygen and then was inhaled through a canister of soda lime, where the carbon dioxide was removed before the air returned to the mouth and lungs.

After its first successful use in escapes from a diving bell in the Chesapeake Bay, the Momsen Lung underwent repeated refinements. Naval engineers added a noseclip to ensure that the wearer would inhale and exhale through the mouthpiece. To improve underwater vision and to protect the eyes, the noseclip was attached to goggles equipped with a valve to control the air pressure behind the lens. And the mouthpiece was given a fin that pressed against the upper lip beneath the nostrils, to prevent sneezing.

Stored with the escape gear was a yellow marker buoy attached to five hundred feet of knotted rope. It was sent up ahead so that it could be followed to the surface. Escaping submariners were to pause every ten feet, where they found a knot, so as to ascend no faster than fifty feet per minute.

A submariner’s ascent had to be slow and measured in order for his lungs to adjust to the decreasing pressure and to avoid the related dangers of oxygen poisoning and decompression sickness. Oxygen poisoning, caused by prolonged breathing of pure oxygen under pressure, is a fatal condition that may come on without warning, causing an epileptic-type seizure. It can occur at any depth beyond seventy feet. It can be avoided by diluting oxygen with nitrogen, which is the chief component of the air around us.

Decompression sickness, or the bends, results when a person who has been under pressure for an extended period undergoes rapid decompression. Nitrogen is always absorbed into the bloodstream along with oxygen, but under high pressure, the amount absorbed becomes much greater. If a diver or submariner under pressure ascends too rapidly, the nitrogen in his bloodstream expands and forms bubbles, causing agonizing pain. Unlike oxygen poisoning, the bends can be cured, through recompression, once the victim has reached the surface.

Thus the Momsen apparatus had to be used cautiously to ensure a slow, but not too slow, ascent. Ironically, free ascent without any device eliminated the problem of the bends. As long as the submariner spent no more than a few minutes equalizing the interior pressure with that outside the sub before opening the hatch, he would not be endangered by nitrogen. And, of course, he wouldn’t be breathing in at all as he rose to the surface.

The entire escape system, with lungs, buoys, and numerous other features, was a masterpiece of technology and engineering. Submarine escape became a highly complicated and sophisticated matter. “Perhaps the technology was too technical,” says Robert Vogel, curator of mechanical and civil engineering at the National Museum of American History. “It is not unknown in the history of technological development for a particular technology to reach beyond the actual need. For a variety of reasons, in the harsh world of reality, it then doesn’t work.”

In the case of submarine escape, the device did little more than impose a complicated solution where a simple one would have sufficed. And the simple solution became, in effect, unavailable, since submariners did not learn about it. With or without the devices, only a handful of men escaped on their own. Those who did invariably survived what one English submariner described as a “ghastly ordeal.”

The case of the German U-57, which hit a mine north of Scotland in 1915, is typical. The U-boat went down in 128 feet of water with twenty men alive inside. The air in the submarine quickly filled with chlorine gas as seawater flooded the boat’s electric batteries. The fumes burned the men’s eyes and made breathing nearly impossible. Their ears ached as pressure increased. They found only four Dräger units aboard; believing their situation hopeless, two of the men shot themselves. Then the captain decided to make one last, desperate effort to save the remainder of his crew by opening a hatch.

To his amazement the hatch flew open and he was drawn out and upward. He had no time to inflate his life jacket or even to take a breath. As he recounted later, “I had no desire to inhale, but to forcibly exhale so that I constantly had to blow air out.” The air in his lungs had expanded as he rose. If he hadn’t exhaled, his lungs probably would have burst. The rest of the crew followed him; seven survived the ascent and were later picked up.

Such sinkings occurred repeatedly during World War I, but survivors were few. Submarines were not universally equipped with mechanical lungs; those that had the gear usually stowed it in inconvenient compartments. Undoubtedly, most men who went to the bottom alive assumed that escape was impossible without some sort of breathing apparatus and didn’t even try to get out.

After the war the search for practical means of escape continued to depend on technology. For a brief while the U.S. Navy found hope in salvage. In the 1920s four sunken subs were actually located and hauled to the surface in time to save the lives of 105 men. As it turned out, those men were very lucky. Conditions had to be close to ideal for a successful salvage to take place. They seldom were, but collision, equipment failure, and human error were the most common causes of peacetime sinkings, and in most cases the submarine was usually close to port.

If a sunken submarine hadn’t suffered serious damage, the crew might have as much as a three-day air supply, allowing time to tow the boat to shallow water and raise it with a derrick or pontoons. But in any but the shallowest water, submarine and salvage ships were at the mercy of the wind, sea, and tide. If the submarine was damaged, it might not withstand being moved. All could be lost if it was bumped on the bottom. And in almost every case, the cost of salvage was greater than the cost of the vessel being saved.

At any rate, the early successes were overshadowed by a growing number of tragic failures. In 1925 a British submarine was overrun by a merchant ship and despite the best salvage efforts was never found. That same year the USS S-51 went down in 132 feet of water with thirty-three men alive. It took nine months for the Navy’s finest salvage team to raise the submarine and retrieve the bodies of her crew. Finally, in 1927, the American submarine S-4 was rammed by a Coast Guard destroyer off Cape Cod. A gale lasting several days hampered salvage efforts, and by the time the S-4 was raised, everyone aboard was dead. For all practical purposes, the use of salvage for rescue was discontinued.

The U.S. Navy now concentrated on a promising device developed by a submariner named Allan R. McCann. The McCann Rescue Chamber was a steel diving bell that could be attached to the escape hatch of a sunken sub at depths of up to 350 feet. It consisted of two compartments and a ballast tank. The ballast tank was emptied or filled depending on whether the bell was ascending or descending. The rescue team rode in the upper watertight compartment; the lower one, which was open at the bottom, could be pumped free of water by the use of compressed air once it had settled over the submarine’s escape hatch. The men in the sunken submarine would then climb through the hatch, into the lower chamber of the bell, and thence into the upper chamber, which could hold as many as seven at a time.

Between 1935 and 1939, a period of major naval buildup, all new U.S. submarines were constructed with special fittings for the McCann Rescue Chamber. They were also equipped with Momsen Lungs, to be used as gas masks if the air in the sunken submarine became unbreathable. The lungs were to be considered for escape only if assistance from the surface seemed unlikely.

There was good reason to rely on McCann’s bell. In 1939 the USS Squalus sank off Portsmouth, New Hampshire, at a depth of 242 feet, with thirty-three men alive. In less than twenty-four hours she was located and a rescue bell lowered, despite high winds and rough seas. “Hi fellas, we’re here,” said the diver in the bell as he opened the hatch of the submarine. The thirty-three men had been waiting in total darkness, chlorine-befouled air, and near-freezing temperatures for twenty-eight hours. Had the diving bell failed, they would by then have been too weak to escape using Momsen Lungs.

At the time, it was universally assumed that if a technical difficulty was encountered with the rescue equipment, escape was hopeless. And, in fact, the longer submariners waited for rescue before donning their Momsen Lungs and before beginning to equalize pressure so they could open the hatches, the dimmer were their chances for survival.

During the same period, just before World War II, instructors at the Naval Submarine School, in Groton, Connecticut, had begun making free ascents from the hundred-foot depths of their training tank, primarily as stunts. Later, trainees, too, started making free ascents, and practiced in the tank with Momsen Lungs, but this activity was directed more toward selecting out those unsuitable for submarine service than toward emergency preparedness.

During World War II most submarine officers agreed that any thought of escape in wartime was a waste of effort, and they resented the escape equipment that took up precious space aboard their craft. Submarine attack forces roamed far and wide, and often at depths from which any form of escape would be impossible. There seemed to be little point in thinking about survival after a sinking.

Fifty-two American submarines were lost during the war. Most of them disappeared without a trace. The only known escape was made following the sinking of the USS Tang, in October 1944. In the midst of a surface attack on a Japanese transport, one of two torpedoes fired by the Tang boomeranged, veering back to hit the submarine. The Tang’s stern sank to the bottom, 180 feet down, and sat there at an acute angle for about fifteen minutes, long enough for one officer who found himself in a pocket of trapped air in the conning tower to escape. He left through the hatch wearing neither breathing apparatus nor life belt. Remembering his experience with free ascent while in submarine school, he exhaled as he rose sixty feet to the surface. He was able to swim about for eight hours before being picked up.

Over the next six or seven hours, the remaining men on the Tang made some four attempts to escape. The effects of building pressure in the submarine and foul air were both physically and mentally debilitating and kept many of the men from even contemplating action. Thirteen of them got out of the submarine, however, some using lungs, and eight or nine made it to the surface alive. Five survived. They were the only survivors out of more than thirty-five hundred Americans lost in submarines sunk during World War II.

One of the men was very close to passing out from a shortage of oxygen when he lost the mouthpiece of his lung about twenty feet from the submarine. “When I lost my lung,” he said later, “I blew the air out all the way to the surface trying to equalize the escaping air the way the lung would have done. On reaching the surface I was exhausted and sick.” He got to a life buoy nonetheless and was picked up about four hours later.

The British and the Germans also lost thousands of men in submarine sinkings during the war, and the British resolved to do something about it. At the end of the war they made an extensive study of submarine escapes. They found that 84 percent of the men who were known to have been alive inside a submarine when it sank had died inside. Another 10 percent had died on the way to the surface. More significant, there had been as many successful escapes without using any form of escape device as there had been with.

The British concluded that a method of free escape should be taught to all submariners. They noted that the Americans had already developed such a technique. But it needed refining. Finally, in the early 1950s, when the late rear admiral Walter F. Schlech, Jr., was in command of the submarine school at Groton, a concerted effort was made to develop a dependable technique of free ascent. Schlech, a submariner who served for thirty-five years in the U.S. Navy, was very much aware of the history of submarine escape when he took command of the submarine school. “We knew of the work the British had done,” he said a year before his death in 1985. “We knew that a system of free escape would work. If you’re down three hundred feet, the air you fill your lungs with is compressed. It’s also richer in oxygen. As you rise toward the surface, and the pressure on your body decreases, the air in your lungs expands. If you blow the air out on the way up, your lungs remain the same, and you’ll have plenty of oxygen to keep you alive all the way to the top. In fact, you can never run out of air. There’s always a liter of air in your lungs that’s never expelled.”

The trick was managing the rate of ascent. “You had to watch the bubbles,” Schlech noted. “If you stayed behind the bubbles, you were okay. If you found yourself catching up with them, you’d have to blow harder. If you were falling behind, you’d hold your breath. That was tricky enough, but if you had to escape at night, you couldn’t see the bubbles to know whether you were rising or not.”

The solution was a British suggestion. Inflate a life jacket while in the submarine. The jacket would be designed with a flapper valve to release the expanding air as it carried its wearer upward. “Once you’re out, you start blowing as hard as you can blow,” said Schlech. “The jacket takes you up and out of the water like a shot. We called the system ‘Blow and Go.’ There was a lot of opposition at first, but eventually it got rid of the Momsen Lungs and all the other equipment, and it’s still in use in depths of up to three hundred feet.”

The military historian Clay Blair wrote in his book Silent Victory, about submarine warfare in World War II, that Schlech’s work proved that “all the emphasis on the Momsen Lung, including training ascents in the sub school’s one-hundred-foot water tower, was an unfortunate error, born of ignorance. It made submariners think that a Momsen Lung was necessary for escape. Thus, in one sense, the Momsen Lung concept may have killed far more submariners than it rescued.”

The U.S. Navy continued to use the McCann Rescue Chamber when practical, but the use of the Momsen Lung was discontinued in 1957. Nearly one hundred years after Wilhelm Bauer had risen unaided from the Brandtaucher, Blow and Go became standard procedure. Except in extremely deep water, man had always had the means of escape at his disposal and had had no better chance with the most elaborate escape apparatus than without it. The only necessary technology was the technology of the human animal—the effective use of one’s own body as an escape machine.

In a final irony, the adoption of this simple means of submarine escape came about too late. By the 1950s the submarine itself was undergoing a revolutionary change, with the development of the nuclear-powered sub, which could spend almost all its time at depths where Blow and Go truly was impossible. Still, the years of research on escape devices were not wasted. Naval engineers put the knowledge gained from their work with the McCann Rescue Chamber and other systems into the design of submarine rescue vessels capable of saving lives at depths of up to five thousand feet. The preliminary work had been done, and the men who had died for want of knowledge of a means of escape had not died entirely in vain. The efforts that failed to save them contributed to new technologies that may one day account for the saving of countless lives at hitherto unapproachable depths.

Ann Jensen is a free-lance writer living in Annapolis, Maryland, who specializes in maritime subjects.

After the tragic loss of the nuclear submarine Thresher, in 1963, the U.S. Navy undertook the development of Deep Submergence Rescue Vehicles (DSRVs). On the basis of knowledge gained from earlier submarine-escape research and from the Navy’s bathyscaphe Trieste, which descended to a record depth of 35,800 feet in 1960, plans were made for six vessels, each capable of carrying a crew of three and twenty-four evacuees.

Thus far, two have been built. The Mystic, just under fifty feet long, was launched in 1971; her twin, the Avalon, was completed a year later. They can operate at depths of five thousand feet after being launched either underwater from a submarine or from a submarine rescue ship on the surface. They also can be transported by plane or by a special trailer on land.

Once on the scene, the DSRV, a sort of modern-day McCann Rescue Chamber, hooks up with an escape hatch on the sunken submarine. The submariners climb into the DSRV, and it carries them either to its “mother” submarine or to one of two specially built, catamaran-like rescue ships.

Neither the Mystic nor the Avalon has been called on for an actual rescue mission so far, nor have the submarine rescue ships. No U.S. military submarine has sunk since 1968, when the nuclear sub Scorpion disappeared off the Azores. All ninety-nine men aboard the Scorpion were dead before any trace of the vessel was even located. The DSRVs remain deployed and ready aboard submarines at sea; the rescue ships serve as platforms for deep-sea diving operations.