In 1931 Sir Hubert Wilkins attempted to operate a submarine under the ice pack north of Spitzbergen. The North Pole was his ultimate objective. With the obsolete, inadequate equipment at his disposal, he was not successful. Since 1931 great strides have been made in arctic surface and air travel, but techniques for under-ice navigation have lagged behind. What are the problems of arctic travel? What are the possibilities?
The Navy icebreaker U.S.S. Burton Island rammed her blunt bow into a pressure ridge for the tenth time and jarred to a halt, stopped again by the arctic ice pack. During the previous three weeks she had made propeller turns enough to drive her some three thousand miles through open water, but the ice yielded only 235 miles to this tremendous expenditure of effort. At times the ship was held immobile by the pressure of the ice. She drifted with the pack according to the whims of nature. In good weather the ship’s helicopter could fly ahead to spot leads of open water or thin ice. Sometimes it was possible to work the ship into one of these and make good progress for a few miles.
This describes a winter expedition into the northern Bering Sea and presents some typical problems encountered by our icebreakers. The Navy is now operating three of these incredibly tough ships. They can perform miracles only dreamed of by northern explorers a few years ago, yet the limitations of an icebreaker are painfully evident to one attempting to work such a ship through heavy polar pack ice. Unless we have a bulky cargo to deliver, there must be an easier way. How about going either over or under the ice!
We do well indeed flying over the ice these days. Except for some difficulties of navigation, flying over the Arctic Ocean is not unlike flying in other parts of the world—that is, until it becomes necessary to stop! Even this can be done occasionally on a strip of smooth, snow-covered ice; though it is a hazardous undertaking at best. But seeing the ice pack from the air, one cannot help realizing the possibilities of under-ice navigation. These possibilities we have largely neglected. There is a surprising amount of open water scattered throughout the ice pack. An icebreaker makes significant progress only in these leads of open water or through relatively thin ice. The bulk of energy and time in icebreaking must be expended in working from one open lead to the next. How much easier and quicker to avoid the ice altogether by ducking under it!
Questions immediately arise. What if our under-ice submarine is trapped and unable to find an “air hole”? How deep must a submarine go to avoid the ice which we know floats low in the water some four-fifths submerged? How can the navigator tell where the ship is? What happens to the gyro compass near the North Pole? And why on earth do we need an arctic submarine anyway? We have answers to many questions now, and we can find out the answers to the rest by actual test.
First of all, what is the nature of our antagonist? Contrary to what seems to be popular belief, the polar ice pack does not cover the Arctic Ocean as one solid sheet of ice. Nor does the ice pack extend downward indefinitely into the polar seas.
Even in the extreme condition of midwinter at the North Pole, there will be openings in the pack. The ice is always in motion under the influence of wind and current. As the ice “rafts” or piles up in one place, a lead of open water must necessarily form on the other side of the moving ice floe. Naturally there is a maximum amount of open water during the summer with its long hours of daylight, but there is still a certain amount even during the coldest winter.
It has been established that sea ice seldom extends deeper than about 80 feet below the surface (except for icebergs and certain “ice islands” that have been discovered between Alaska and the North Pole). This figure of 80 feet represents an extreme condition. Ice never does freeze that thick. Under constant sub-zero temperatures, sea ice will freeze to a thickness of about five feet in one winter. As the ice becomes thicker during subsequent winters, the rate of freezing becomes slower. When the ice is about eight feet thick, freezing along the under side ceases; because the ice insulates the water from the cold air above. In the course of a dozen years or so an ice floe will normally drift across the top of the world and will be carried south between Greenland and Spitzbergen by the ocean currents. Our ice floe may eventually grow as thick as fifteen feet by virtue of snow building up on top of it. In any part of the Arctic Ocean ice of a variety of thicknesses will be found. Except for rafted and hummocked areas, however, there will be no ice thicker than about fifteen feet; there will also be thinner ice depending on its age; and there will be leads of open water.
During summer the ice wastes away rapidly. The edge of the pack recedes north ward. Puddles form on the ice surface, and smaller floes melt completely. The extent of the ice is least late in August or early in September. At this time there may be no ice within 100 miles of the north coast of Alaska; and there will be open “lakes” several miles across even in the vicinity of the North Pole.
How do we find this open water as we grope along under the ice in our submarine? There are two methods. Sonar equipment is capable of differentiating between ice and water above the submarine. It can also present a continuous picture of the conditions overhead, whether the ice is rough, or smooth, and how deep it extends. Further, the water of the Arctic Ocean is clear and transparent out beyond the continental shelf. Near land the water usually contains sediment from the great arctic rivers. An open water area could be selected by looking up through the high angle periscope. Powerful floodlights on deck should also permit visual inspection of the underside of the ice.
If the bottom of the ice is rough with projections deep under the water, we can visualize a surface of pressure ridges and hummocks. This ice would undoubtedly be many feet thick from several layers of ice being piled on top of each other. On the other hand ice that is smooth on the bottom must be smooth on top. This smooth ice must also be relatively thin, because it would be a single layer. In case we might occasionally find it necessary to create our own open water, this would be the place to attack.
For emergency purposes, an explosive charge placed against the under side of the ice will produce good results. Ice is comparatively weak in tension. An explosion naturally vents upward. This combination should be able to produce a hole big enough for the submarine to poke her conning tower up into the air. If a submarine is to be especially modified for ice work, however, it should certainly be a feasible engineering project to build a mechanism capable of boring through fifteen feet of ice. Ice boring will require a completely untried technique. The submarine must be “topped” against the ice even as a conventional submarine would rest on the bottom of the sea. The superstructure would require modification to provide tearing surfaces for the vessel to rest against the under side of the ice. With several hundred tons of positive buoyancy from expelling water ballast, the submarine could be securely anchored to the ice during the boring process.
Navigation will present a major problem, increasing as the ship nears the pole. While the magnetic compass is virtually useless in the American Arctic, it might furnish some help in east longitude away from the magnetic pole. We know from ships that have penetrated within 350 miles of the North Pole that a regular ship’s gyro compass will still perform fairly well at that latitude though its directive force is quite small so near the pole. Much closer than 350 miles, a non-directional gyro and astro compass combination could be employed as in polar air navigation. Celestial navigation is still the only method of fixing position in the Arctic Ocean. Bad weather frequently prevents this. Infrequent opportunities for celestial sights whether to fix position or to determine direction by astro compass would be an inconvenience but not necessarily a prohibitive obstacle.
From 1941 to 1945 German U-Boats operated along the ice fringes near Spitz- bergen, and they conducted war patrols in the Barents Sea and Kara Sea along the Russian northern sea route that leads around Siberia. These submarines ranged as far as Vilkitski Strait at the east end of the Kara Sea. Through necessity these Germans experimented with under-ice navigation. On more than one occasion U-Boats were trapped by the polar pack and could not escape other than under the ice. But the U-Boat sailors discovered that their craft were never helpless in the ice, because they were able to dive under the ice and come up in open areas to charge batteries when necessary. Since World War II our submarines have occasionally penetrated into the fringes of the ice pack, but there has been no concerted effort to develop a capability of under-ice navigation. The participation of the submarine U.S.S. Sennet in Operation Highjump to the Antarctic in 1946-47 is an example. The submarine was taken into the ice pack with the other ships of the task force, but no attempt was made to dive the submarine under the ice.
But even if one will grant that a submarine might be able to operate across the Arctic Ocean, there still remains to establish whether or not there is any reason to take a submarine into the far north. What can a submarine do that an icebreaker or aircraft cannot do? There is general agreement that the Arctic is strategically important. Because the Arctic Ocean is the central area of most of the earth’s land masses, naval operations there will be of utmost importance. For national security certain far northern strategic areas must, if necessary, be defended. As peacetime missions, the Armed Services must be capable of supporting weather and other arctic stations. It seems obvious that a variety of arctic missions will be increasingly necessary both in peace and in war.
Arctic weather data is important to forecasting in other parts of the world. The Air Force now makes regular weather flights to the North Pole to get this data. A submarine could provide arctic weather information.
With an increase of flying across the Arctic, it becomes increasingly important to provide rescue facilities. A submarine could assist in this function. And with the present dearth of radio aids to navigation in the arctic, a submarine could also act as a navigation beacon for aircraft.
While a submarine cannot carry a large amount of cargo, it could establish and support temporary air bases, weather stations, and radio beacons on the ice pack.
The Arctic Ocean is one of the least known parts of the earth. A submarine would be an ideal vehicle for oceanographic research which would uncover the secrets of the Arctic Ocean and reveal its effects on the rest of the world.
In the event of war, peacetime functions could be expanded to include the use of submarines as radar pickets to extend the early warning perimeter in the direction of hostile airfields. And of course our submarines could prey on shipping and conduct reconnaissance during the summer along the Arctic sea routes, as the Germans did during World War II.
Submarines have already demonstrated that they can conduct limited operations inside the fringes of the polar ice pack. How much more can they do? It seems they may have some important capabilities to contribute toward development of the arctic, both in time of war and in peacetime. But that is something we shall never know for certain until we give the submarines a thorough opportunity to prove themselves under the ice.