Ice can cover submarine operations. And submarines armed with missiles operating in the Northern Marginal Sea Ice Zone littorals can threaten much of Canada and the United States. With the decommissioning of the last Sturgeon-class SSNs, how does the U.S. Navy answer the threat?
Shallow estuaries of large rivers are among the world's most difficult geophysical environments, where only relatively small, highly maneuverable, and properly ballasted submarines can survive. Considering their sea ice cover, Northern Marginal Sea Ice Zone (MIZ) littorals present the most challenging environment of all. The Northern MIZ is simply the arctic and subarctic waters that are ice-covered in winter and open in summer. The Subarctic MIZ is the area below the Arctic Circle (66°33'N).
There are many noteworthy marginal ice zones in the Northern Hemisphere, but three strategically important MIZ estuaries are of particular interest to us: the Gulf of St. Lawrence, the Beaufort Sea Shallows, and the Kara Sea.
A serious concern of nations bordering on MIZ areas is the threat from submarine-launched land attack missiles. Threats to merchant shipping and fishing fleets in the Gulf of St. Lawrence and in the Kara Sea are self evident. Prudhoe Bay production and pipeline facilities are crucial components of U. S. strategic logistic reserves.
The Gulf of St. Lawrence
The Germans fought a successful littoral campaign in Canadian territorial waters during World War II. Canada suffered severe losses and shipping in the Gulf was at times paralyzed. Closure of the Gulf of St. Lawrence to traffic was a routine expectation during the ice season. The Germans compounded the problem by threatening traffic during the ice-free shipping season as well. In the Battle of the St. Lawrence, U-boats sank 20 merchants (66,566 tons) and damaged four more inside the gulf between 12 May 1942 and 25 November 1944. During the same period, one warship (900 tons) was sunk and another damaged. At 16 attack sites in the mouth of the St. Lawrence River and south of Anticosti Island, more than 57,000 tons (85% of the total) were sunk. The deepest penetration of the river's mouth by a U-boat was more than halfway to Quebec City.
During 2-6 May 1943, U-262 entered the Gulf through the Cabot Strait and transited under pack ice to gain an open water approach to North Point, Prince Edward Island. U-262 was to pick up escaped German prisoners of war, but the POWs did not show because security at their camp had been tightened as a result of an earlier unsuccessful escape attempt. Michael Hadley characterized the U-262 effort as "one of the finest failed operations on record."
An extraordinary unopposed intrusion took place on 22 October 1943, when U-537 planted an unmanned automatic weather station in Northern Labrador. The station was not discovered and identified as German until July 1981.
But in terms of human tragedy, the most serious loss was suffered on 14 October 1942. The Nova Scotia to Newfoundland ferry (North Sydney to Port aux Basques), the Caribou, was sunk by U-69 in the Cabot Strait. There were 137 deaths, including women and children. The memory of this sinking was painful, but "had no long term effect, for in matters of national defense, Canada has no memory. Almost 40 years later, in April 1982, U.S. Ambassador to Canada Paul Robinson had to remind a Canadian naval conference in Vancouver that Canada still can't even defend the St. Lawrence River."' The lessons not learned during World War II still are with us today. We are faced with what is probably the most formidable tactical problem in maritime history. Canada, with limited resources and a relatively small population, apparently wants the world to know that it intends to neglect the challenge rather than solve it.
Environmental conditions in the approaches to Cabot Strait and inside the Gulf of St. Lawrence are nightmarish. Pack ice, icebergs, shallow fresh water, density layers, fog—upward refraction favoring submerged submarines—make it nearly impossible for surface ASW forces to detect and attack interlopers.
Ice conditions in the Gulf of St. Lawrence are influenced by temperature, wind, and currents. "In most parts of the Gulf, the ice . . . drifts into the open Atlantic mainly through Cabot Strait. ... Most of the ice that first leaves the Gulf comes from the central area between Anticosti Island and Cabot Strait. However, this central region may continue to be ice-covered until late March or early April. . . .."
The Gulf of St. Lawrence is relatively deep. A wide swath of water with water depth of 100 fathoms or deeper stretches from the mouth of the St. Lawrence River south of Anticosti Island and out through Cabot Strait. However, "deep" is in the eye of the beholder. In 1967 Sir Arthur Hezlet observed that: "In general . .nuclear submarines may be expected to operate in waters of over a hundred fathoms." This remark assumed no ice cover. We know that the U.S. Navy's short-hull Sturgeon (SSN-637)-class nuclear-powered attack submarines have operated effectively in ice covered seas with a total water depth of barely 16 fathoms. This is an extreme example, but submarines crossing over the Bering-Chukchi Shelf in winter face a thousand-mile track with water depths of 30 fathoms or less.
Effective performance in the Gulf requires a submarine that can operate submerged in fresh water. Low-salinity water at the mouth of any river will challenge a submarine on a mission there because of the effects of density on buoyancy.
The problems of upward refraction and density layers were identified during World War II, but never solved. U-boats had the run of the Gulf.
An enemy nuclear-powered or air-independent-propulsion submarine easily could enter the Gulf of St. Lawrence undetected in March and launch a land-attack missile with characteristics similar to the Tomahawk (range 1,600 nm). A launch site in a Labrador fjord would be even easier and more secure. From there, a submarine could attack any city as far south as New York and even Philadelphia.
Confused sonar conditions, pack ice, and icebergs would allow an orderly retreat toward the east and into Denmark Strait, with further sanctuary there.
The Beaufort Sea
Detailed knowledge of the bathymetry of the Beaufort Sea came 100 years after Briton Robert M'Clure, commanding the Investigator, explored Alaskan coastal areas between Bering Strait and Banks Island in 1850.
Robert McWethy, a submariner, served as executive officer of the Navy icebreaker Burton Island (AGB-1) from 1949 through the winter of 1951. The first pioneering survey work since M'Clure was carried out in the Beaufort during the summers of 1950 and 1951. The Barrow Sea Valley was discovered, and a highly accurate bathymetric contour chart of the Beaufort Sea was produced.
Prudhoe Bay oil operations dominate the Alaskan North Slope. When oil was discovered on the North Slope in 1968, Navy Petroleum Reserve No. 4 became a strategic national asset. Three rivers (Colville, Sagavanirktok, and Mackenzie) feed fresh water into southern Beaufort Shallows, with substantial effect in summer. Prudhoe Bay facilities are flanked by two sea valleys, Barrow to the west and Mackenzie to the east.
As in the Gulf of St. Lawrence, an enemy submarine could use the ice cover and shallow, low-salinity water for sanctuary before and after lobbing land attack cruise missiles into Prudhoe Bay.
The Kara Sea
During World War II, German U-boats operating in the Barents and Kara Seas paralyzed Northern Sea Route shipping in Siberian coastal regions.
In August 1942, Operation Wonderland sent the pocket battleship Admiral Scheer and two U-boats, U-602 and U-252, into the Kara Sea, where they rounded the northern tip of Novaya Zemlya (it was a mild ice year). The mere presence of the Wonderland units was enough to keep ship movements to a minimum in the Kara.
By the summer of 1943, 20 U-boats, supported by a forward base at Kirkenes, Norway, were available for deployment in arctic waters. Mines were laid off the west coast of Novaya Zemlya during July and August.
On 1 October 1943, a three-boat wolfpack sank all (four) merchantmen of a westbound convoy escorted by an icebreaker and three small antisubmarine ships (one of which also was sunk). The action took place in the Northeastern Kara, amid intermittent snow squalls and patches of fog.
During the Cold War, the possible presence of Soviet strategic submarines in the Kara's East Novaya Zemlya Trough was a matter of great concern to the United States. Attrition of Northern Sea Route traffic transiting between the southern tip of Novaya Zemlya and Vaygach Island probably would have been a priority mission in a hot war with the Soviets.
Both the Yenisey and Ob rivers discharge large amounts of fresh water into the Kara bathtub.
Shallow Water Operations Under Ice
Access to the Arctic Ocean from the Pacific in winter requires a transit under the ice canopy over the Bering Chukchi Shelf for 1,000 miles with water depth less than 180 feet. Maneuverability is crucial under ice; transits in very shallow water are extremely difficult and require superb shiphandling. It often is necessary to accept 25 feet beneath the keel and 25 feet clearances overhead, while avoiding deeper ice ridges. Under heavy ice, maneuvering decisions may be required as often as every two minutes. Control of longitudinal trim within plus or minus 1/8th degree is crucial to the interpretation of the ahead looking beam of the high-resolution sonar. A maximum speed of advance of about four knots is typical. The turning diameter must be small enough to ensure the submarine can turn inside the range at which an ice ridge is identified as a threat.
It is axiomatic that a short submarine is more maneuverable than a long one. Any submarine longer than 350 feet probably is incapable of meeting the maneuverability requirements under ice in shallow water. A length-to-diameter ratio (L/D) of about 7.6 (e.g., L=243ft, D=32ft) would be more than adequate. Salinity and density layering in shallow littorals are also complicating factors when buoyancy is considered. Large variable ballast tanks are required to allow operation submerged in low salinity waters.
Warfighting Under Ice
The U.S. Navy carried out warfighting exercises in Cabot Strait on an annual basis from 1959-1962. Major exercises conducted by Commander Submarine Squadron
Ten included:
- 1959 SubIcEx 1-59, 5-10 March ComSubDiv 101 (McWethy) Trout (SS-566)/Harder (SS-568)
- 1960 SubIcEx 1-60, 7-26 March ComSubDiv 101 (Catlin) Bang (SS385)/Tench (SS-417)/Tusk (SS-426)
- 1962 SubIcExX 1-62, 8-24 March ComSubDiv 102 (Cramer) Skate (SSN578)/Entemedor (SS-340)/Tusk (SS425) and HMS Astute/HMS Alderney (late in the exercise)
Commander Robert McWethy was a driving force in 1959 (as ComSubDiv 101) and 1960 (as SubLant operations officer). He provided valuable insights, particularly for the diesel submarines involved. But the loss of the Thresher (SSN-593) on 9 April 1963 curtailed any arctic operations for several years.
Two other meaningful exercises under MIZ ice were:
- 1970 (November): Hammerhead (SSN-663) versus Skate (SSN-578) in iceberg country (Davis Strait)
- 1973 (March): Hawkbill (SSN-666) versus Seadragon (SSN-584) in the Bering Sea
Instead of determining requirements for warfighting in the ice, these exercises again demonstrated that specialized requirements unique to under-ice combat must be developed. The exercises with the Sturgeon-class submarines demonstrated that an arctic submarine must be capable at least of rapid ascent into the ice canopy at speeds of 3-5 knots to evade and gain the sonar advantage in an upward refracting and highly reverberant medium.
Warfare under the sea ice is strictly the province of submarines alone—i.e., singular, one-on-one combat. Other platforms, joint forces, and network-centric warfare are irrelevant. Intercommunications, essential to joint warfare, are impossible within or through the sea ice cover.
But further exercises are not possible because of the decommissioning of the last Sturgeon-class submarines, the only class that can operate in shallow ice-covered seas. Science cruises, carried out in the deep central Arctic Ocean, benefit only the scientists. They do not support warfighting capabilities.
In 1987, investigations of under-ice warfighting requirements began at the Arctic Submarine Laboratory (ASL), San Diego—the only facility of its kind in the Western world. Its experimental pool could support true sea-ice experiments at full scale (sonar, sail impact), as well as model experiments in the adjoining towing basin, which models the sea ice-covered Bering Sea (40/1 scale).
In a 1992 reorganization, the Naval Sea Systems Command shut down the laboratory facilities, declared them obsolete, and designated them for demolition. However, a 1997 reorganization moved ASL within the Command, Submarine Development Squadron Five. Indications are that the facilities will be saved from being demolished and placed in barren layup with necessary engineering documentation to make later reconstitution possible.
Russian Naval Posture
During the summer of 1995, Russian Rear Admiral Valeriy Aleksin, Head Navigator of the Russian Navy, announced to the world: "He who controls the Arctic controls the world." A few weeks later, a Typhoon-class SSBN launched a single SS-N-20 ballistic missile with multiple independently targeted reentry vehicles (MIRVs) (ten dummy warheads) from the geographic North Pole. There were reportedly ten hits at a test range west of Murmansk.
In December 1997, Admiral Aleksin pointed out that 70% of Russia's state boundary lies in sea waters. "We must be ready to repel a naval attack by any enemy having [cruise missiles]. . . [O]ur Navy needs at least 70 SSNs . . . and up to 40 modern conventionally powered submarines."
A formidable submarine-launched rocket torpedo, in service since 1977, and available on the open market today, the Shkval is a real threat to any ship operating in littoral shallows. Characteristics are:
Diameter: 21-inches
Length: 26.90 feet
Speed: Approx. 200 knots
Range: 12,000-16,000 yards
Propulsion: Solid-fuel rocket motor
Functional: Straight running to approx. 1,300 feet deep" A more devastating model of Shkval, reportedly under development, would have an acoustic search speed of 60 knots and would attack at 300 knots.
Summary Perspective
Any large submarine will only be able to operate in deep ice-covered waters, but cannot take effective advantage of the protection offered by the ice canopy in a warfighting scenario.
The general characteristics of an interim arctic capable submarine appear to be:
- Highly maneuverable
- Relatively small (L/D < 7.6)
- Capable of operation submerged in fresh water
In the present fiscal and political climate, it is not possible to gain support for an Arctic-unique submarine. The immediate goal would seem to be, however, to develop a highly maneuverable submarine that can transit under ice in shallow water. This would ensure U.S. dominance in shallow, open-water littorals and restore operational surveillance capability in MIZ shallows.
In recent years, pleas for smaller submarines have been ignored. Since 1985, however, technology (permanent magnet motors, power electronics, automation, etc.) has matured and should be exploited. With innovative application of modern computer-aided design techniques, we should be able to overcome the mind-set that it takes 12-13 years to design and build a nuclear attack submarine. This period could be halved at a considerable cost savings.
An insightful 1996 research paper crystallized recommendations that include:
Assignment of a single submarine-acquisition manager, who would be responsible for the entire submarine-acquisition program including the propulsion plant, hull design and the all-inclusive combat system. (Emphasis is in original.)
It also recommended reconstituting the General Board approach, to specify requirements and oversee research and development, rather than using a series of ad hoc panels and commissions established by Congress, the Department of Defense, and the Navy. This also should make it possible to rebuild and revitalize the Engineering Duty Officer Corps.
Recent congressional testimony not only recommended prototyping new submarine classes, but encouraged Congress to institute "a standing statutory requirement for manifest across-the-board superiority of American boats." (Emphasis is in original.) Others have recommended that the United States:
- Provide two classes of attack SSNs
- Build limited numbers of large submarines from existing programs for heavy payload missions.
- Develop smaller, highly maneuverable prototypes to work in littoral shallows with and without ice cover
Submarine Missions
The attack submarine mission has been challenged by new demands for littorals deployments. Shallow water ASW requires both hunter and hunted submarines to bottom and deploy torpedoes. Similarly, mine survey and detection in support of amphibious operations require mine detection sonar and deployment of unmanned underwater vehicle area survey devices. (Hostile bottom influence mines constitute a potential nightmare, demanding innovative approaches to neutralization.)
A "strategy-to-system" methodology mandates "next step" linkage of desired systems to technology. The methodology must be structured carefully and directed to ensure that innovative, realistic, and cost-effective research and development is applied to the new missions. A single-service problem requires single service vision-not top-down, joint vision. The importance of this approach is underscored by a logical sequence whereby the mission mandates the submarine characteristics. Far too often, we have started with a propulsion plant and wrapped a hull—usually too big—around it.
Unanswered Questions and Recommendations
U.S. plans involve construction of one attack class of nuclear-powered submarine. The Russian view is that, ". . . it seems quite clear that the multi-purpose submarine carrying winged missiles is the ship of the future."
Is a multi-purpose submarine possible in today's world? Both the United States and Russia should be prototyping smaller, more agile submarines that can use MIZ shallows to offensive and defensive advantage.
Singular multi-purpose sentiments notwithstanding, in 1997 Russia announced three forthcoming variants of a new design, the Amur. These submarines can be provided with AIP propulsion and are available for export.
The first U.S. prototype should be carefully designed with a power plant that eventually will be suitable for evolution to a fully arctic-capable prototype. Research and development to design a future hull configuration for impacting the sea-ice canopy at three-five knots should be carried out in parallel with design of the interim shallow water transitor.
Do we have a suitable weapon for deployment to ice covered littorals?
The Russians have Shkval. In the United States, we recognize that avoidance of the undersea surprise demands close cooperation between researchers and operators.
We must start development of an under-ice weapon for use in littorals. If an adversary's small AIP submarine threatens MIZ shallows on either side of the Arctic Basin, will any of us be ready to oppose it?
Mr. Boyle served in the Sea Owl (SS-405), the X-1, and the Skate (SSN-578) between 1953 and 1960. From 1961 until his retirement in 1985, he worked as a research general engineer at the Arctic Submarine Laboratory, San Diego.
Dr. Lyon retired in 1996 after 55 years of civilian submarine service, 50 as the U.S. Navy Chief Research Scientist for Arctic Submarine Technology. In 1947, he founded t he Submarine Research Facility, San Diego, and in 1966, the Arctic Submarine Laboratory, which he directed until 1984. The authors participated in more than 40 deployments under ice. As this issue went to press, we learned that Dr. Lyon passed away.