The ship was on a collision course with the target. From my vantage point, I estimated we were making 10 knots. The span of blue water separating us from the solid mass ahead shrank rapidly. From the height of the target above water, I estimated it to be at least 12 feet thick. We would soon know whether the Manhattan, with her reinforced steel hull and “spoon handle” bow, was as strong as her designers claimed.
The jagged vertical edge of the giant ice floe raced beneath me as I looked down from the 65-foot overhang of the bow. An instant later, there was a sharp jolt as the rounded stem met the rock-hard ice. There was no hesitation as the 150,000 tons of the Manhattan knifed through the ice floe. The bow lifted slightly, perhaps six inches, and I mentally compared this with the eight-foot rise I had experienced when the icebreaker Westwind (WAGB-281) had rammed a polar pack.
Shouts rang out from the group of men around me as we watched the white corrugated surface of the ice floe slide beneath our feet at 10 knots. A loud screeching filled the air and made conversation difficult. It was as though the steel hull was scraping against a coral reef.
Aft, on the bridge, the captain’s face broke into a guarded smile. The tension that had existed on the ship eased. Although the mammoth tanker was a long way from completing her epic voyage through the Northwest Passage, she had, at any rate, won her first encounter with the polar ice.
It was then 2 September 1969, and we were underway in Baffin Bay heading toward Thule, Greenland. I had joined the vessel on 23 August a few days after receiving the most welcome orders I had yet to receive in the Coast Guard—“Proceed to Chester, Pennsylvania, and board the SS Manhattan for a voyage through the Northwest Passage to Prudhoe Bay.” I was to take part in Humble Oil & Refining Company’s $40,000,000 venture to prove that the legendary Northwest Passage could be conquered by a commercial vessel.
The Manhattan was at Pier No. 2 at Sun Shipbuilding and Dry Dock Company when I first saw her. The now familiar bow loomed out ahead of the 1,000-foot hull in a grotesque shape that promised to herald in a new era in icebreaking. Developed by a fellow naval architect, Commander Roderick White, U. S. Coast Guard, while he was attending Massachusetts Institute of Technology, his “down-breaking” bow had received scant publicity. However, now that icebreaking capability had become an important factor in economic considerations, it was recognized that a design which would allow for continuing movement through an ice pack, rather than using the conventional ramming mode, had definite advantages.
White’s bow meets the ice at a shallow, 18-degree angle as compared with the 30-degree angle of the typical icebreaker bow. The spoon handle gradually increases the contact angle as it slides up over the ice, finally allowing for an application of the ship’s bow weight directly downward.
An ice pack, insofar as strength characteristics, is similar to a pane of glass—strong in compression and weak in tensile strength. The perpendicular application of the ship’s weight readily breaks the ice. Model tests of the spoon handle bow, which were conducted at the U. S. Naval Arctic Submarine Laboratory, San Diego, California, showed this new bow to be 30 to 40% more effective, in the continuous breaking mode, than conventional icebreaking bows. New icebreaker construction will soon incorporate this design.
Once on board the Manhattan, the Coast Guard/Navy four-man team, of which I was a member, was caught up in the anticipation that filled the air. We also felt the undercurrent of anxiety that further delay might cause cancellation of the project. The original departure date had already slipped past the scheduled 15 July, owing to the complex problems encountered in strengthening the ship.
Since conversion of the Manhattan into the world’s largest icebreaker within an eight-month period was an impossible task for a single shipyard, the 940-foot vessel had been sliced into four sections and towed to various shipyards for alteration. More than 10,000 shipyard workers participated in the conversion. The sections were then towed back to Sun’s yard for reassembly.
The original bow was removed and stored. The new spoon handle bow, 65 feet long and weighing over 5,000 tons, was fabricated at Bath, Maine, and towed to Sun shipyard where it was welded in place. It was designed to protrude 11 feet beyond the rest of the hull on each side to allow open water along most of the ship’s length so as to reduce ice friction.
The primary strengthening alteration was the installation in the wing tanks of 90 huge K-frames made up of one-inch steel I-beams. These K-frames were designed to prevent the hull from being crushed by the tremendous pressure of the polar ice floes. A cofferdam-type ice belt, 9 feet wide and 30 feet high, was then attached to the original Manhattan side shell. The plating of this ice belt consisted of 1.25-inch high tensile steel. The ice belt ran 670 feet from the new bow to the engineroom, ranging from 8 feet above to 22 feet below the waterline. The 8,500 tons of steel used in the hull-strengthening alteration exceeded the total steel weight of a World War II, T-2 tanker. Two five-bladed, 22-foot-diameter, ice-strengthened propellers, with blade tips five times the normal thickness were installed; moreover, both rudders were reinforced with additional steel plating.
The dimensions of the world’s first icebreaker/tanker after the conversion were: length overall: 1,005 feet 6 inches; beam (bow): 154 feet 6 inches; beam (stern): 132 feet; draft: 52 feet 1 inch. Additional quarters allowed for a total crew of 126, including 74 technicians, scientists, and observers.
On 24 August at 1117, Captain Roger A. Steward, a veteran shipmaster of 23 years at sea, looked down over the port side and ordered “Let go fore and aft.”
As the whistle sounded a resounding long blast, two tugs eased the Manhattan out of the berth and headed her down the Delaware River.
Excitement was high. We were to attempt a voyage that sailors have dreamed of since 1497, when Sir John Cabot searched in vain for a short route to the Orient. All hands were aware that the waters that would have to be traversed were both sparsely charted and ice-infested. We were aware, too, that a score of explorers had attempted unsuccessfully to establish a sea route through the legendary Northwest Passage.
Time passed swiftly as we cleared Belle Isle Strait and headed into the frigid Labrador Sea. The scythe-like stem threw out a foaming bow wave as we headed north at 16.5 knots.
High on the spacious bridge, which was filled with the most advanced electronic navigational gear, were three licensed mariners, the master and two staff captains. Aft on the heliport deck, the flight crews were making last-minute checks on the two Sikorsky S-61 helicopters. The ice research parties were assembling coring equipment. The data they gathered would be very important in analyzing the strength of the ice for future technical and economic feasibility studies of shipping oil in supertankers through the Northwest Passage.
The satellite navigator or integrated navigation system required input from five sources. The basic input was provided by a navigation satellite receiver with recorded radio signals from the four special-purpose earth satellites placed in polar orbit under the U. S. Navy Navigation Satellite Systems program. Three other inputs were acceleration, gyroscope signals, and latitude correction.
The last and most critical input to the system involved the use of a pulsed doppler sonar and associated computer equipment as originally developed for the Navy’s Deep Submergence Systems program. However, we were to find that large chunks of ice forced below the hull as the vessel cut through the polar pack caused the doppler to “lose lock,” which resulted in an erroneous ship’s velocity input. This, in turn, resulted in a navigational error of three miles for each knot of velocity error.
Since mechanical speed input was important to the navigation system and other systems, Lieutenant Commander Roderick Edwards, U. S. Coast Guard, recalled the sailing ship era method of using a chip log to determine speed. While not complicated, it was cold work throwing chips of wood over the side and calculating their time of passage. Naturally, the people who operated this old but reliable system were soon known as “chipmunks.”
The communications system consisted of a powerful three-kilowatt transmitter which was able to overpower the notorious Arctic radio blackouts caused by electromagnetic interference. The transmitter, some 500 times more powerful than the usual commercial ship radio transmitter, made possible excellent long distance communications. Unfortunately, while able to transmit a great distance, it interfered with the important telemetry equipment and its use had to be curtailed.
An unusual house-like steel structure with chimney-like projections located amidships on the main deck covered the twin diesel engines which powered the world’s largest heeling system. It would be used to rock the Manhattan free if she were beset in the ice. Twelve wing tanks, six on each side, with a capacity of 2,000 tons of sea water, were cross-connected with two pipes, 7 feet in diameter. The 3,000-h.p. twin diesels could shift the 2,000 tons of water from port to starboard, a distance of 65 feet, in 60 seconds. This induced a roll on the 150,000-ton Manhattan from three degrees port to three degrees starboard, or a dynamic force sufficient to break an 8-foot thickness of ice.
One of the most interesting spaces on board was the instrumentation room in the ’midships house, which was equipped with a myriad of electronic telemetry equipment to record the readings which would flow from sensors throughout the ship. Three hundred sensors would transmit stresses on hull scantlings and machinery. Other gauges and meters checked pitch, roll, torque on propellers and rudders, engine power output, and speed. The 32 engineers and scientists were busy acquainting themselves with the intricate gadgetry.
A special analysis room had been established in the after house. This provided an area where the eight-man special analysis team, of which I was a member, could study and evaluate the collation of information gathered in the instrumentation room. Closed-circuit television receivers would enable us to observe the break and flow of ice around the prow, along the sides, and astern when we had to back down.
Early on the morning of 30 August, as the ship headed up Davis Strait, we saw our first iceberg. The huge chunk of glacier ice towered 60 feet above the water and was estimated to weigh in excess of 1,000,000 tons. As the giant mass passed astern, it was apparent that while the Manhattan might be able to negotiate pack ice, she would have to stay well clear of the icebergs, some over ten times her size.
Data gathered by the International Ice Patrol showed that during August in the Baffin Bay-Davis Strait area, there are some 40,000 icebergs underway and drifting south. This number does not include “bergy bits,” house-sized pieces, and the smaller “growlers,” named for the characteristic sound they create as they toss and turn in a seaway.
The lookouts kept a watchful eye ahead. During the next few days, as we hugged the west coast of Greenland, Captain Steward changed course frequently to maneuver past hundreds of huge bergs. The navigators on the bridge were learning that radar can give a misleading picture of what lies ahead—a small pip on the scope might be the return from a small floe, a growler, or a towering 1,000,000-ton iceberg, depending on the aspect ratio and surface condition.
Radio reports from Halifax Ice Central indicated that we would meet open pack ice near Cape Dyer. The Baffin Bay pack ice is sea ice as compared to icebergs, bergy bits, and growlers which are pieces of fresh water glacier ice.
Early on the morning of 2 September, five hundred square miles of open pack ice were broad on the port bow. Captain Steward changed course 60 degrees and headed toward it. We made contact at 0715. As noted, the first encounter was a success, and we steamed on with a new confidence.
As we sailed north across Baffin Bay, we were joined by the CCGS John A. MacDonald, the powerful 315-foot Canadian Department of Transport icebreaker. She was to become a most important member of the team.
We dropped anchor at Narssurssuk, near Thule, Greenland, on 4 September. The Manhattan had completed the first leg of what proved to be her 10,000- mile round-trip voyage. Our one-day stay was uneventful but provided some diversion for the crew. Some of us visited the nearby native village which consisted of three huts, 12 Eskimos, and 47 yapping huskies. One of the village elders generously offered to sell me the “last” handmade Eskimo figurine in the village for only $20.00. When I returned to the ship with my prized possession, I found that 25 shipmates had also purchased the “last” figurine.
The next day we nosed into Lancaster Sound, the historic eastern entrance to the Northwest Passage. The weather was fair with the air temperature at 35 degrees and the sea water a chilly 32 degrees. Ice coverage gradually increased, but we had no trouble moving through the open packs at a speed of 10 knots. In the deep blue water we saw schools of frolicking Beluga whales, averaging 10 feet in length and over a ton in weight.
As we stood on west through Parry Channel, we were joined by another important member of the task group—a Coast Guard C-130 operating out of Thule. The giant aircraft was equipped with the latest aviation electronic equipment known as Side Looking Airborne Radar (SLAR).
An elaborate scouting system called for the C-130 to fly 500 miles ahead along the Manhattan’s intended route each day and make a photographic survey of 2,000 square miles of ice-covered seas. Every third day the C-130 would airdrop the radar information, in the form of a strip map on photographic film, to the Manhattan. The film would be correlated with the flight chart to form a “mosaic radar picture” of ice conditions ahead.
A second member of the aerial contingent was a Canadian DC-4 with a special ice-scanning dome. The aircraft was equipped with infrared cameras and laser beams. This aircraft would also airdrop the film of the area ahead to the Manhattan. The infrared film reveals the hardness of the ice. As ice grows older, the salinity decreases and eventually it becomes rock hard.
During September 1969, the “Arctic Fox,” a C-121 SuperConnie aircraft from Oceanographic Development Squadron Eight, with ice observers and civilian scientists from the Navy Oceanographic Office on board, operated out of Thule in “Project Birdseye” to provide extensive ice survey and reconnaissance for the Manhattan.
Dennis Farmer, a U. S. Navy ice interpreter and reconnaissance specialist, was a vital element of the Manhattan’s team. He was specially trained at the U. S. Naval Oceanographic Office, under the direction of Dr. Walt Whitman, to analyze output from the high resolution side-looking radar, the infrared equipment, and the optical laser.
In this way the Manhattan was provided with a “road map” of the ice ahead to show concentration, leads, pressure ridges, and floe sizes. The infrared film would enable us to determine what part of the ice ahead was the hardest.
The laser beam is focused perpendicularly and depicts the ice profile, i.e., the height and frequency of ridging. A 30-foot pressure ridge above the ice, for example, indicates an ice projection some 100 feet below the water. Although such subsurface projections are mushy and not as hard as the ice near the colder surface, they present obvious hazards to any future commercial submarine traffic.
Entering Barrow Strait, we encountered multi-year ice for the first time. The coverage gradually increased until there was no open water. The pack was now five feet thick, but the Manhattan knifed her way through at seven knots, throwing bus-sized chunks to either side.
We arrived at Resolute, the northernmost outpost in the Canadian archipelago, on 6 September. Although weather conditions were still good with the temperature above freezing, in February 1967, Resolute had recorded a temperature of –65 degrees Fahrenheit.
The Coast Guard icebreaker Northwind (WAGB-282) made rendezvous with the task group at Resolute. She had already traversed the Northwest Passage from west to east via the Coronation Gulf route to join us. The next day the three vessels got underway—the Manhattan leading the way, with the MacDonald and Northwind in line astern.
As we plowed through Barrow Strait at five knots, we saw our first polar bear—a 12-foot giant. He is the king of the beasts, at least within the Arctic circle. He scarcely looked up from his meal as the 1,000-foot tanker slid within a hundred yards. His whitish fur speckled with red, he made an interesting picture standing in a pool of blood with the carcass of a large seal at his feet. Behind a mound of ice an Arctic fox watched and waited for his chance at the bones.
Beyond Barrow Strait, we faced the most dangerous leg of the voyage—Viscount Melville Sound and then the ice-choked McClure Strait.
On 7 September, the task group entered Viscount Melville Sound. The ice was now six feet thick and getting thicker. We were encountering 10-foot pressure ridges.
This was the ice condition for which the Manhattan had been converted. The question uppermost in our minds was, could she maintain a continuous icebreaking mode or would she have to resort to backing and ramming? All engines were developing full power and she was making five knots on a heading of 272° true.
Astern, the Northwind was having difficulty maintaining station and was gradually dropping behind. A machinery failure en route to Resolute had put one of her six engines out of operation. The loss in power was to prove critical.
Our first real problem occurred the following day. At 0541, I was awakened by a sudden silence which gripped the ship. The reassuring throb of the engine was stilled. I peered out the port into the Arctic twilight, and it appeared as though the Manhattan had been suddenly displaced onto a desolate range of small white mountains. There was no movement, and as far as I could see, there were 12-foot pressure ridges and snowy hummocks. I dressed hurriedly, grabbed my parka, and ran up one deck to the bridge.
As I entered the bridge, Captain Steward ordered, “Full ahead. Give it a jingle.” There was a noticeable vibration as the twin shafts whirled at maximum r.p.m., but the vessel did not move. The 43,000-s.h.p. could not overcome the friction of the ice pressing against the ship’s sides. We were beset in Viscount Melville Sound.
During the night the Northwind also had become stuck and was unable to ram herself free. The MacDonald had reversed course to go to her assistance but ran into difficulty breaking through the high pressure ridges. Because of the Manhattan’s previous successful icebreaking performance through 6-foot ice, the decision was made to come about and assist the Northwind to break out. However, we learned the hard way that, while 43,000 s.h.p. was sufficient to move ahead on a set course, it was not sufficient to allow for extensive maneuvers.
Two of the three vessels in the task group were now beset, and it was time for a conference. A short time later, Captain John D. McCann, U.S.C.G., commanding officer of the Northwind, landed on the Manhattan’s helicopter deck, followed by Captain Paul M. Fournier, R.C.N., commanding officer of the MacDonald. Stanley B. Haas, Humble Oil project manager, Captain Steward, Captain Frederick A. Goettel, U.S.C.G., senior U. S. Coast Guard representative, and Captain Thomas Pullen, R.C.N., Canadian Arctic expert, met with the two icebreaker skippers to discuss the situation.
Since we were stopped, and while the conference was in session, it seemed a good opportunity for the scientists in the ice party to test their equipment and make some experiments.
As soon as the go-ahead was given, the deck crew winged a boom over the side and lowered away the sleds and snowmobiles. The four bright orange sleds contained augers, picks, and instruments. The sleds were pulled by two snowmobiles. The scientists, led by the chief of the ice study team, Guenther Frankenstein, trekked off across the hummocked, snow-blown ice-scape. Every 100 feet along the trail a marker was planted in case of a sudden blizzard. By twos and threes the individual study groups dropped off until only Frankenstein and two assistants reached the stopping point 6,000 feet ahead of the Manhattan.
The ice parties performed three basic tests. One was to measure salinity and temperature, the two most important data points for determining ice strength. To do this, a 3-inch diameter core sample is drilled from the ice. Using a hand drill, it takes five minutes to drill a foot. Sometimes the core would be 12 feet thick. It would be cut up into 6-centimeter units and tested for temperature. These samples were placed in plastic containers and carefully marked as to relative depth position. Back at the ship’s laboratory, they were analyzed for salinity. At each drilling point the two-man team would make an on-the-spot measurement of the ice strength, using an instrument calibrated to gauge the deflection each ice sample makes in a wire ring. At the same time other teams would measure the thickness of the ice by simply drilling a 1½-inch hole in the ice and inserting a steel tape measure into the opening.
A study of a 6,000-foot stretch in front of the ship would take four to six hours, depending on the ice thickness. The best part of the study was the break for lunch. There was something special about eating a ham sandwich perched on a cake of ice in the middle of a 100-square mile ice flow only 50 miles away from the magnetic North Pole.
In later ice experiments, after the team returned to the ship and the sleds and snowmobiles were secured the Manhattan would get underway and plow through the ice course marked out by the ice scientists.
The readout from the transducers, showing ship’s velocity, propeller revolutions, torque, and other pertinent data would then be correlated with the known ice conditions through which the ship was passing.
That afternoon, with the ice party and snowmobile back on board, the conference of captains broke up. Captain McCann of the Northwind had made a difficult decision. Although his cutter was an Arctic veteran d 25 years, with only five engines on the line, she could not assist in carrying out the mission. Captain McCann sent a priority message to the Commandant, U. S. Coast Guard, recommending that the Northwind, which the MacDonald had freed from the ice, be detached and proceed independently to Prudhoe Bay. The reply was affirmative.
That evening, the MacDonald, a sturdy veteran of ten seasons in the Arctic, managed to cut her way through the pack to relieve the pressure around the Manhattan. After opening an area off our stern, she proceeded up the port side within ten yards and cut a side relief channel in the ice.
At 1815, the Manhattan’s enunciator rang up “full astern” and we backed down two ship lengths. Then, with a double-jingle on “full ahead,” the twin propellers developed their 43,000 s.h.p. within 40 seconds and we were once again moving ahead. Everyone on the bridge stood silently, waiting. We did not have long to wait. Within 100 yards, the behemoth came to a halt. Captain Steward reversed and then charged the ice again. At last, after three rams, the Manhattan was able to maintain forward motion and we proceeded at four knots.
The voyage on through Viscount Melville Sound was a series of skirmishes with polar packs varying in thickness and hardness. With the “road map” provided by the air reconnaissance, we were able to predict the ice conditions ahead. This was verified by the ice research teams which were flown off by helicopter and landed ahead of the ship.
With her twin rudders and twin propellers the Manhattan had proven to be extremely maneuverable in open water and in annual ice; however, it had been demonstrated that compacted, multi-year ice reduced the giant tanker’s maneuverability to the extent that she could not fully exploit weak ice sectors or open leads that appeared. Nonetheless, moving ahead on a set course, she demonstrated that, without having to stop, back, and ram, she was able to break a path in 6-foot ice with pressure ridges of 12 feet.
It was also determined that when the Manhattan was required to break ice in a backing and ramming mode, the available astern power, 13,000 s.h.p., was not sufficient to permit adequate backing.
On 9 September, off the northeastern corner of Banks island, one of the Manhattan's helicopters landed an ice party on a polar floe a few miles from the ship. As the helicopter rested on the ice, the starboard wheel broke through the ice and the craft tipped over on its side. One member of the party narrowly missed being struck by the rotor blades as the aircraft toppled over.
The maneuverable MacDonald was able to reach the damaged helicopter and swing it aboard with her crane. Then the MacDonald hove alongside the Manhattan and transferred the aircraft. The accident confirmed that, in future Arctic operations, helicopters should be pontoon-equipped for ice landings. The small-diameter wheels have a much higher print pressure, more than 500 psi, than pontoons.
With the “Johnny Mac,” as the Manhattan’s crew called her, alongside, the two crews were able to visit back and forth. The distinctive black berets with crown insignia, which the 96 men in the Johnny Mac’s crew wore, were swapped for the Manhattan’s patch featuring the Humble tiger with earmuffs.
To a U. S. Coastguardsman who has been used to the stark purity of grey metal bulkheads, angle irons, and armored cable crisscrossing the overhead of every compartment, the luxurious accommodations of the Manhattan had been a revelation. However, the decor of the Canadian Coast Guard’s MacDonald outdid even the Manhattan. In addition to rich mahogany paneling and varnished wooden rails, each cabin had a fireplace. Of even more interest to the dry Manhattan’s crew was the fact that there was a well-stocked liquor locker and a regularly-scheduled happy hour.
All during the passage, as the Manhattan cleaved through the polar packs of Lancaster Sound, Barrow Strait, and Viscount Melville Sound, we knew the real challenge would be the ice-choked McClure Strait. The passage is open to the north and the constant onslaught of winds off the polar ice cap force the pack ice from the Beaufort Sea into the narrow neck of water. Pressure ridges as high as 30 feet have been observed in the area. The Strait has been transited only once by a surface vessel and that was in 1954 when the Northwind penetrated from the west.
A glance at a chart shows that the Manhattan had two alternative routes to reach Prudhoe Bay, one via Prince of Wales Strait, which is protected from the Arctic Ocean by Banks Island, and the other is McClure Strait. If the Manhattan could not cut through the pressure-ridged packs of McClure Strait, she would come about and head for the other.
On 10 September, with Banks Island off to port appearing like a long white layer cake, we stood into McClure Strait. The first day the Manhattan maintained a speed of two knots through ice 10 feet thick. Pressure ridges were from 10 to 20 feet high. The crack of the thick ice around the bow sounded like far-off detonations of dynamite. The second day, however, the thickly compressed polar pack proved too much. We were beset off Banks Island in the vicinity of Mercy Bay at 74° 20’ North and 116° 4’ West. It was the same location where Commander Robert McClure’s bark, the Investigator, had been beset in 1853. After spending 18 months waiting for the polar pack to release the vessel, the Royal Navy officer completed his transit of the Northwest Passage by walking across the icy expanse of the strait now named after him.
Although we were not fearful of having to follow in Commander McClure’s footsteps, after 20 hours of being beset, the alternative did enter our minds. It would be an understatement to say we would have been disappointed if we had had to fly out by helicopter.
At another captain’s conference, the decision was made to abandon the McClure challenge. The two-ship task group would leave McClure Strait and complete the voyage via Prince of Wales Strait. The only problem was how to break free and come about. The C-130 dropped a SLAR photograph which showed a weak ice sector to the north with leads and reduced ridging. If we could just break through to the weaker area, we would be able to reverse course.
Captain Steward and his officers decided on the strategy to get the Manhattan underway. The MacDonald was requested to break through to us and plow up the ice astern. She would also try to cut a pressure relief channel down the port side. The heeling system was energized, and within a short time, the Manhattan commenced rolling like a giant metronome. Since it was imperative that the maximum 43,000 s.h.p. be developed by the two steam turbines, emergency measures were taken. The evaporator, sanitary systems, and all auxiliary steam lines were secured.
By late in the afternoon of 11 September, the Johnny Mac had nibbled away at the ice, and it was time to make the effort. The engine room telegraph handles were shoved to full astern. The engine vibration felt good on the soles of our feet as the twin shafts whirled up to a maximum of 90 r.p.m. The tanker moved astern, rolling six degrees. After we had backed down half a ship’s length, she stopped. The captain ordered full ahead and again we picked up speed. With a crunching roar the spoon handle bow smashed against the icy barrier. We lurched to a stop. Again we went astern and again we rammed ahead. At last, after five rams, the Manhattan broke through the polar pack and moved steadily toward the open leads to the north.
Once in the Prince of Wales Strait in the lee of Banks Island there were only scattered ice floes, and icebreaking ceased to be a problem. But there was a new problem, of equal gravity—uncharted shoals. The Strait is 150 miles long and about 12 miles wide with some depths charted as shallow as 10 fathoms. Surveys of the Strait have been infrequent and those were not considered reliable. The navigational charts for the area warn the mariner to exercise caution when navigating these waters. The watery slot is also swept by strong currents. Halfway through the strait, a small island, Princess Royal, bisects the channel leaving a navigable width of six miles on either side.
Captain Steward, acutely aware that the Manhattan was drawing 55 feet, did not take his eyes from the Fathometer. Near Princess Royal Island, the Fathometer recorded two shoal areas, one 12 fathoms (17 feet below the keel) and the other 14 fathoms. These shoals, coupled with a strong variable current, estimated at three knots, and drifting ice floes, resulted in our being set to within one mile of the island.
The experience vividly pointed out the need for further hydrographic surveys in the strait, as well as the entire Northwest Passage, before year-round traffic can safely transit the region.
On the night of 14 September, the Manhattan slipped quietly into the calm waters of Amundsen Gulf. The polar pack had moved offshore and left the route to Prudhoe Bay ice-free.
We hove to off Prudhoe Bay on 19 September and dropped anchor. The shallow slope of the seabed and lack of reliable charts prevented us from approaching closer than 20 miles to the shore. Our saga of the Arctic was over—we had logged 4,600 treacherous miles in 28 days. To commemorate our arrival, a symbolic gold-plated barrel of oil was lifted aboard and the voyage was now a memorable chapter of maritime history.
I departed the Manhattan for the flight back to reality and Washington, D.C., where there was an immediate series of debriefings. The Coast Guard Merchant Marine Technical Division, with statutory responsibilities, insofar as concerns ship construction and safety equipment requirements, wanted to be ready for plan approval, with answers to the questions that would arise if oil companies made the decision to start construction of a new generation of supertankers.
The voyage had convinced me of one thing—it was possible to build icebreaking supertankers that could successfully negotiate the ice-covered Northwest Passage the year-round. I foresee ships of 250,000 deadweight tons, 1,200 feet long, 180 feet in beam and drawing 80 feet, plying trade routes north of the Arctic Circle. They must have propulsion machinery capable of developing 100,000 to 150,000 s.h.p. for forward motion and have 65% of this power available for backing.
Since the ability to back down in the ice will be of primary importance, it will be necessary to design a stern which can break ice. The stern must also provide protection for the propellers and rudders against the ice.
In any event, the hull shape of the new icebreaking supertankers, with increased drafts, will provide protection for the propellers. Drafts as deep as 80 feet will place the propellers in a protected location some 50 feet below the ice pack.
Use of the latest development in propeller design—the controllable pitch propeller—will facilitate maneuvering the ship in the ice. This arrangement allows the vessel to develop maximum power astern instantly, since the shafts do not have to change their direction of rotation.
The designing of the Northwest Passage tankers will not only introduce new hull shapes but will also incorporate metal fatigue considerations. In the aircraft industry, metal fatigue has long been of primary concern in structural design. Now, the shipbuilding industry will have to give metal fatigue similar consideration.
Unlike other tanker operations where wave-created bending moments are the primary stress considerations, the ice-breaking function will place tremendous cyclic loads on the vessel. A ship operating in pack ice will undergo three times the number of load cycles as a ship traveling the same distance in the open sea. As the bow meets the ice, force is applied to the hull girder. As the ice fractures beneath the bow, the load is suddenly removed and the cycle repeats itself. These alternating stresses will create a fatigue potential which must be compensated for during design.
In addition to the cyclic loads, the extremely low temperatures will emphasize metal fatigue, and will require the use of a low-carbon, high-manganese steel, possessing a nil-ductility temperature characteristic sufficient to withstand the cyclic loads and resist brittle fracture at such temperatures.
An ideal design innovation for icebreaker tankers, which may be possible now, would be to remove all appendages, i.e., rudders, propellers, struts, and bilge keels. A combination bow-and-stern thruster could be used in lieu of the conventional rudders. Foreseeably, a water jet propulsion system could be developed to be used in place of propellers.
The problems connected with an oil pollution “fail safe” design will have to be resolved because of international environmental concern. It has been suggested that future icebreaking tankers be constructed with doubleskin hulls. An alternative method of construction might be the extension of the cofferdam type ice belt from above the waterline to the turn of the bilge.
All of the considerations in new design to provide icebreaking capability and pollution control require a great deal of steel and horsepower. How much of each must be designed into the Northwest Passage tanker remains to be answered. It is now a question of economics. Without doubt, a new sea route has been opened, unlocking not only the oil riches of Alaska’s north slope, but also the fantastic mineral wealth buried within the Arctic Circle.
While the last decade saw a landing on the moon, this decade will see the ice-covered straits in the Arctic Circle, both above the North American continent and Eurasia, become international sea routes. Although the managements of industry must still make the decisions necessary to exploit these new opportunities, it can be predicted that, by 1973, supertankers will shuttle through the Northwest Passage. By 1976, huge ore carriers will be moving millions of tons of ore from Arctic islands to ports around the world. By 1979, container traffic between Europe and the Far East will be routed “across the top.”
__________
A graduate of the U. S. Coast Guard Academy in 1963, Lieutenant Keith served as a deck-watch officer in the Eagle (WIX-327). He subsequently served as a deck/engineer watch officer in the Chautauqua (WHEC-41) and in the Gresham (WHEC-387). In 1966, he attended the University of Michigan and received M.S. degrees in Naval Architecture and Mechanical Engineering. Upon graduation, he studied at the Ship’s Structures Laboratory, Det Norske Veritas, Oslo, Norway, towards his Ph.D. in Naval Architecture. In 1968, he was designated Coast Guard project officer for the conversion of the SS Manhattan to an icebreaker/tanker. He is currently serving in Merchant Marine Technical, U. S. Coast Guard Headquarters.