When viewed in the light of our strategic and scientific goals in the polar regions today, one may raise some serious questions about the adequacy of our icebreaker construction program. Although a new icebreaker has often been included in broad scope shipbuilding schedules, she has never survived beyond the preliminary stages of approval and financing. For one reason or another, a new icebreaker always has had to take a back seat to other items adjudged more important at the time.
U. S. Navy and U. S. Coast Guard representatives have frequently reported that there are insufficient icebreakers available to carry out the tasks required of them in the polar regions. The opening of the St. Lawrence Seaway and the emergence of Alaska as a state have greatly increased the requirements. The fact, too, that our seven Wind-class icebreakers are 20 years or more in age, well past the prescribed life of other comparative naval vessels, compounds the problems.
Recently the precarious state of our icebreaker availability was emphatically demonstrated when the USS Edisto (AGB-2), just returned from six months in the Antarctic, had to be despatched to the Arctic to evacuate 21 scientists and their equipment from a disintegrating ice island off the east coast of Greenland. The fact that the USS Atka (AGB-3), which originally had been sent to perform the job, had been seriously damaged by striking a rock in Boston Harbor on the way up, provided little solace to the crew of the Edisto.
Our icebreaker force, due mainly to the heavier commitments at Greenland and the Canadian Arctic is based as follows: the USS Glacier, USS Edisto, USS Atka, USCGC Westwind, and the USCGC Eastwind, on the East Coast; and the USS Burton Island, USS Staten Island and USCGC Northwind on the West Coast.
An improvement in this polar icebreaking force may soon be forthcoming. The recent decision to place all icebreakers under the Coast Guard instead of having icebreaking responsibilities shared by the Navy may be a step in the right direction. It is reasonable to expect that since the icebreakers will represent a relatively large share of the Coast Guard’s commitments they will receive more attention. And, because they will be among the largest of all the Coast Guard’s vessels, they will not have to compete against the construction of even larger or more sophisticated types as they have had to in the Navy.
If current reports in Washington are true, the Coast Guard is already envisioning an icebreaker powered by atomic energy. Long a gleam in its eye, the Coast Guard’s first attempt, in 1958, in gaining the necessary approval for such a ship was fruitless. The House of Representatives Committee on Merchant Marine and Fisheries and the Senate Committee on Interstate and Foreign Commerce reported favorably on a bill to authorize construction of a nuclear-powered icebreaker for the Coast Guard but it was never enacted into law.
Icebreakers have progressed a long way from the early wooden polar vessels, which though heavily reinforced in most instances, were wall-sided so that the pressure of hundreds of tons of ice could bear directly against their hulls. The loss of the Jeannette in the Arctic Basin off Siberia in 1881, in which Lieutenant George W. De Long, U. S. Navy, and most of his crew afterward perished from starvation, provides a graphic example of this kind. Ships were crushed and lost in numerous other expeditions during the 19th century, or they became so helpless and immobile in the ice as to negate the purpose of their expeditions almost entirely.
The finding of personal items and equipment from the ill-fated Jeannette off the coast of Greenland resulted in the building of a special kind of ice-ship by Fridtjof Nansen of Norway. To test the validity of the Arctic currents suggested by such an action, he wanted a ship strong enough to withstand the tremendous ice pressures sure to be encountered in his proposed drift across the Arctic Basin.
Thus, Nansen’s Fram was different. Her underwater portion was shaped to resemble the cross section of a cylinder or barrel. No outer protuberances would offer resistance to the ice. If great enough, the ice pressure, it was believed, would literally raise the ship out of the water much like a pea is forced out of a pod by pressure from the fingers. Encroaching ice would advance under the hull and expend its force against ice on the other side. That the ship was in every way successful was proved by her three-year drift from a location off the northern Russian coast, across the top of the world, to emerge finally free of the polar ice fields in the Atlantic Ocean on 13 August 1896.
The United States is a late comer in the field of polar icebreakers. Except for past, small, polar vessels like the Coast Guard’s cutter Bear, and the Northland (PG-49), which did not have great power and relied on pushing heavy ice aside rather than riding up on it and breaking it by sheer weight, we had never before engaged in this kind of ship operation.
Our polar expedition ships, with the exception of Admiral Robert E. Peary’s Roosevelt, consisted mainly of beefed-up sealers and whalers. These did not fight the ice, but bided their time to sail into areas that were temporarily clear of ice. Sometimes they were caught. Sometimes they were crushed.
World War II, however, provided the impetus for us to take positive steps in polar icebreaking when it became apparent that we would have to afford protection to Greenland or have it fall under Nazi control. Congress authorized the construction of four Wind-class, or “deep-draft,” icebreakers for use in the polar and sub-polar regions. Three of these icebreakers—originally named the ; Northwind (WAG-278), Westwind (WAG-281), and Southwind (WAG-280)—were transferred to the custodianship of the Soviet Union at their request, and Congress accordingly authorized funds to replace them.
After the war, the Navy took control of the USS Burton Island (AG-88) and the USS Edisto (AG-89), and the Coast Guard assumed administration of the Northwind. In 1950 and 1951, with the return of the three icebreakers from the Soviet Union, the original Westwind reverted to the Coast Guard while the other two joined Navy ranks as the USS Atka (AGB-3) and the USS Staten Island (AGB-5). In 1955, the Navy built an additional icebreaker, the Glacier (AGB-4), of greater capability but with the same basic design features as the Wind-class icebreakers.
As our interests and responsibilities in both polar regions have increased greatly since World War II, the requirements for these icebreakers have likewise increased in these widely separated areas of differing configuration. Each has its own peculiar icebreaking problems. Eight thousand miles is the distance between the two operating zones, a voyage track further augmented by intervening ports of call and irregular land masses. Fortunately, the summer operating seasons, when optimum operating conditions prevail, are six months apart, but this leaves little time for winter operations or for badly needed overhauls or upkeeps. Icebreaking, with its repeated shocks, causes metal fatigue and heavy engine wear. Present-day operations involve long periods of time, a factor which tends to aggravate deterioration and hasten breakdowns.
In 1946-47, an expedition composed of 13 ships, known under the code name of HIGH JUMP, carried out extensive photo missions around the periphery of the Antarctic continent. The icebreakers Northwind and Burton Island broke ice for the central group of ships which had to transit a record 600-mile-thick ice belt in the Ross Sea. In the ensuing year, the Burton Island and the Edisto completed these operations by establishing controls in situ for charting.
Present Antarctic Deep Freeze Operations, which began with the support of the U. S. scientific effort in the International Geophysical Year of 1957-58, embrace an average of nine vessels each year of which four are icebreakers. With continued executive backing these operations will no doubt be a yearly requirement. The recent signing of an Antarctic Treaty, freezing claims and providing for the free exchange of scientific data between signatory nations (of which the Soviet Union is one) has been a stabilizing item in the gathering and studying of scientific information in south polar and sub-polar regions.
In the Arctic, the establishment of a number of joint United States-Canadian weather stations at strategic locations established a requirement for icebreaker support. Construction of the Early Warning System, air fields, and scientific stations (during the 1957-58 IGY) have added to this, although the Canadian Government is now supplying a large portion of this support with added icebreakers.
It appears likely that there will be increased commercial activity along the icebound coasts of Alaska. Although mineral resources of the North American Arctic are only partially known, those that are may become valuable enough, due to a change in domestic reserves or curtailment of imports in an emergency, to render ship transportation feasible for their exploitation.
One of our icebreakers is already employed each season in a variety of jobs off the Alaskan coast, including native health care, law enforcement, marine safety, mail delivery, icebreaking, fisheries patrol, and other state and federal co-operative missions.
Except for nuclear-powered submarines, icebreakers are the only ships which can gather oceanographic data from controlled platforms within the polar packs. For this reason, their oceanographic work schedules are almost always more than they can fulfill at any one time. The amount of work that they can do in this category alone, if given the opportunity, almost defies description.
Miscellaneous tasks such as the rescue of ships entrapped in the ice, plane crashes in the polar seas, and possible atomic submarine failures in these areas may require assistance which because of the nature of circumstances can only be effected by an icebreaker or by icebreaker-based helicopters.
Because the Coast Guard is also engaged in ice clearance in the navigable waters of the continental United States in support of maritime commerce, an increase in the number of polar icebreakers would also lighten the workload of smaller icebreakers, especially in the event of unusually severe winters on the East Coast.
Fundamentally, it appears that the number of icebreakers should be such as to satisfy the following specific functions: (1) icebreaking in support of domestic commerce; (2) icebreaking in support of military operations; (3) icebreaking in support of national scientific goals in the polar regions. Surely a hard, calculating look should be taken of the capabilities of our icebreakers in relation to the requirements generated by these functions.
The transfer from a conventional ship, particularly a lean, swift destroyer to an icebreaker is rather a startling one for a ship- handler. Heretofore, he has avoided all contact with solid objects such as floating ice or dead whales. Now, he finds himself suddenly confronted by a task requiring him to do just the opposite. Gone also is that feeling of lively responsiveness which allows a ship to dash here and there in a welter of foam. In its place is a sensation of ponderous, yet purposeful power. Pleasure and satisfaction come, not from “kicking up one’s heels” when executing a “change of axis” in a screen formation, but from bludgeoning ice and outwitting it in its most threatening moods. It is a thrilling moment for a commander to see the results of his efforts at close hand.
The author, who has spent nearly 15 years in Arctic and Antarctic operations, mostly in the capacity of commanding officer, commodore, or observer aboard each of the Wind- class icebreakers, or the Glacier, or numerous ice-convoy ships and polar ships of other countries, has known this thrill and, as a result, has formed definite conclusions about our present icebreakers.
He believes that the diesel-electric driven Wind-class icebreakers were well conceived and of excellent design at the time of their construction. Besides having a round underwater body constructed of If inch-thick high tensile strength steel, they included such innovations as a helicopter flight deck, an automatic heeling feature, where powerful pumps transfer water or liquid from one set of tanks to another in order to effect a rocking motion helpful in breaking the grip of ice, and an aloft conning station in the mast. The originally fitted forward motor and propeller assemblies were removed when polar operations showed them to be especially vulnerable in the varying ice concentrations of the polar regions.
The excellent visibility provided by their short forecastles and low freeboard is advantageous when maneuvering in the ice. Quick responses to power demands are made possible through linkage controller systems located within the pilot house and on each wing of the bridge. The exceptionally long cruising radius of the Wind class is well-appreciated insurance on long periods of isolated icebreaking.
Among Wind-class shortcomings, one must surely list the cramped living quarters and virtually non-existent scientific work spaces. In the open ocean their motion in a seaway is notoriously bad. During storms, frequent damage to boats, topside cargo, boat cradles, and other exposed equipment occurs because of the low freeboard and excessive rolling. A late modification in installing passive anti-roll tanks has, however, cut down the rolling to some extent. Lack of air-conditioning is sadly felt during transits through the tropics on voyages to and from the Antarctic. Inadequate hangar space often results in a high incidence of deterioration to helicopter frames and engines due to salt air and spray.
At the risk of incurring the wrath of Wind-class personnel who seem to be extraordinarily loyal whenever the larger Glacier is mentioned, it must be stated that her added power and space, improved engine and rudder control facilities within her hollow foremast at the aloft conning station, and permanent helicopter facilities make the Glacier a better icebreaker in almost every respect. Even with bent and broken propeller blades, the Glacier has been observed to break more ice than an undamaged Wind-class icebreaker.
Where the Glacier is particularly deficient, however, is in her cruising radius. She consumes as much as 25,000 gallons of fuel each 24 hours of full-power icebreaking as opposed to 10,000 gallons for the Wind-class. It was in large part for this reason that a decision was made to have the Glacier accompanied by a Wind-class icebreaker during the 1960 and 1961 Bellingshausen Sea explorations in the Antarctic.
Though the Glacier is an improvement on the Wind-class icebreakers, she, in turn, can be improved upon. Reference to the table below shows how our icebreakers compare to recent types of icebreakers built by the Soviet Union, Canada, and Argentina. It may be also interesting to note that our icebreaker tonnage stands behind the first two countries.
Most of the commanding officers of our icebreakers agree that we should have more space for embarked scientists in any new icebreakers. Work spaces, laboratories, and instrumentation should be provided for hydrography, meteorology, oceanography, marine biology, rocketry, ionic physics, and other geophysical studies. Balloon storage and launching areas with associated telemetering equipment are required. There should be a cold room laboratory for ice physics and monitoring apparatus for satellites.
And, if air-conditioning has not as yet been installed in U. S. icebreakers, neither have circuits which would make possible the cross- connection of any generator to an opposite main motor. This would be a particularly desirable feature in case of an emergency or breakdown.
Whereas any kind of icebreaker can perform most of the duties required—e.g., convoying and opening up a harbor—a particular exigency may demand a particular feature. Given these and other parameters, we want to ensure that we get the best icebreaker possible for our investment. We surely want increased reliability, better performance, and longer cruising radius.
Our icebreakers have had a rather unfortunate history of propeller damage due to striking ice. Whether this is the result of over-initiative on the part of our icebreaker ship- handlers occasioned by necessary operations in severe ice conditions or because design criteria or construction materials are at fault is a moot question.
The apparent success of the special Superstone blades recently installed on the Glacier tends to indict both our present design and the strength of materials now in use. Year after year, the Glacier had bent or broken propeller blades in preparing the ship channel through McMurdo bay-ice in the Antarctic. Wind-class icebreakers have been almost as unlucky. The loss of icebreaking services during reinstallation of propellers can be critical as well as expensive.
The new propellers, while being cast of a stronger magnesium-nickel-aluminum bronze and 12 per cent chrome-stainless steel, are of approximately the same over-all dimensions, i.e. diameter, pitch, blade area, as the former ones. But the blade thickness ratio is about 1.5 times the original, and the leading edges are sharper for ice cutting. They are frequently referred to as “clubs.” To date no deformation or breakage has occurred.
Many technicians argue that one-piece propellers should be used because of better strength and hub design—providing casting flaws inherent in large castings can be eliminated. No value accrues from separate bolted construction since propeller changes must always be accomplished in a drydock and the unit as a whole has to be balanced anyway.
The general rule of thumb about propellers is that three-bladed ones are more efficient and that each blade is stronger than four- bladed ones. However, a very efficient four- bladed propeller can be designed which would have the advantage of presenting smaller gaps between blades with less chance of the ice hanging up on the blades.
Another approach to the propeller-vulnerability problem is a redesign of our icebreaker stern underwater form to afford more protection to the propellers when the ship is backing down. The installation of hull baffles forward of the propellers or a shift to hydro-jet propulsion are others.
Perhaps the practice of fitting icebreakers with three shafts, one along the centerline and two at the wings, a feature long followed by the Russians and of late by the Canadians, is really a worthwhile answer in this regard. The only difference is in the application of i power; the Soviets employ 50 per cent power t to the center shaft and 25 per cent to each of the wing shafts, whereas the Canadians divide the total power equally in their ships. Its proponents claim the following advantages for the three-shaft installations:
• Reduced vulnerability of the centerline propeller due to its more advantageous center- line location.
• Reduced vulnerability of wing propellers. Smaller propellers may be used because reduced power is available for each of the wing shafts, thereby bringing the tips deeper below the surface of the water.
• More power remains in the event of damage to one screw.
• With one screw directly ahead of the rudder, steering is improved.
• The three-shaft installation makes possible a better arrangement of machinery spaces so that flooding or fire in any one complete engineroom would not render the icebreaker helpless.
• Damage to any propeller will affect steering far less than damage to one propeller in a two-shaft system due to the imbalance of forces in the event power cannot be applied to the damaged propeller.
• Reversal of wing propellers while the icebreaker is charging has greater effect in ensuring that the ship does not become stuck at the forward point of progress while breaking heavy ice.
In commenting upon the performance of the Canadian version of three-shaft installation, the former master of the John A. MacDonald writes:
While handling this vessel during my period in command, I cannot report that I experienced any evidence of unequal torque, in fact I would submit that I found MacDonald ideally responsive during manoeuvring with the equal division of power on each shaft.
During icebreaking, a great deal of working astern in ice, particularly in winter operations in the Gulf of St. Lawrence is required, and at the outset I found MacDonald possibly a little more difficult to control than our twin screw icebreakers, however, in experience gained by applying power on any desired shaft when required this disappeared and she was found to be capable of working astern as well as any other icebreaker in our fleet.
I always considered by result that the centre propeller provided the major thrust and effectiveness in breaking ice, and many times contemplated that more power would be desirable on the centre shaft. This could well be advantageous.
Icebreaking ability, often—and quite mistakenly—is defined as the thickness of ice that a ship is capable of breaking. Other factors being constant, the thickness of ice which can be broken actually depends upon the amount of free surface adjoining the ice. A solid, monolithic sheet of ice imposes the most difficult conditions. As this icebreaking ability is dependent upon the form of the ship, the displacement, the thrust, the location of the center of gravity, the physical properties of the ice, and perhaps other variables, the design features within this listing should be so constructed as to obtain the optimum performance.
Since the heaviest icebreaking is effected by “ramming”—the bow rising up on the ice and then sinking through—icebreaking ability in this instance depends directly upon the magnitude of the downward force generated on the ice at the bow. The choice of the 30° bow angle presently used on all icebreakers is the result of trial and error. Lessening the angle increases the downward acting component of force so that the ship either becomes “stuck” after ramming ice or shoves the ice up in a pile forward of the bow.
A study made at the Massachusetts Institute of Technology suggests a new concave- type icebreaking bow which would have the advantages of both the lesser and the 30° bow angles. Other valuable suggestions from the same source to increase simultaneously the downward thrust exerted and reduce the extracting requirement demanded after each charge are: the employment of a blunter bow, and a decrease in friction through the application of nonviscous coatings (lubrication, heating, or Teflon).
The task of convoying cargo ships through the ice perhaps causes the greatest compromise in icebreaker construction. As the preferred course is usually a series of courses along a track at those points where the ice floes are weakest and where the ship can proceed with the least difficulty, a short-hulled icebreaker is desired.
Ease in maneuvering is also helpful in breaking out beset ships. The sharp changes of course made by such an icebreaker, both voluntary and involuntary, render the chore of station-keeping extremely difficult for cargo ships behind the icebreaker. As a result, they may be unable to keep within the swept lane and be forced out into the pack with possible chance of damage and temporary besetment. Longer icebreakers more nearly have the turning circles of conventional ships and also provide more space for cargo, laboratories, and engines.
The only criterion of the beam should be that it be wide enough to clear an adequate path for convoyed ships. As a rule, an icebreaker breaks a channel about one-half a yard wider than herself. While it is possible that sections of the ice will upend simultaneously on each side of the icebreaker and reduce the width of the channel astern by twice the thickness of the ice, such action is considered extremely unlikely. Too large a beam may also enable ice to pass under the icebreaker so that it will be forced against the propellers.
The low-beam ratio of icebreakers with no parallel middle body gives good maneuverability. Too low a ratio, however, presents a large metacentric height, making a vessel stiff and uncomfortable at sea. The trend, within certain limits, is for higher ratios.
The complete answer to longer cruising radius for icebreakers is, of course, nuclear propulsion. The advantage of being able to cruise for over a year in the ice fields without refueling is self apparent, and particularly so in the quest for scientific information.
The Soviet Union appears to be so pleased by the technical success of its nuclear-powered Lenin that two more similarly powered icebreakers are planned, if reports are correct, with construction of the first probably starting in 1969.
A new icebreaker named after one of Captain Robert F. Scott’s famous expedition ships, the Terra Nova, is on British drawing boards. Probably the very latest icebreaker to be completed is the Japanese 320-foot Fuji of 8,566 tons full load displacement, built at the Tsururni Shipyard of Nippon Kokan. This ship, designed to take advantage of experience gained during six Antarctic expeditions made by the Soya, a ship converted for polar exploration, has such desirable features as fully air-conditioned living quarters, three helicopters for rapid transport of personnel and cargo between ship and shore installations, anti-roll devices, an elevator, a convelator for cargo, and safeguards to protect the rudder and propellers. Diesel generators drive her four motors at a maximum of 12,000 horsepower giving the ship an icebreaking ability amounting to about 20 per cent greater than our Wind-class icebreakers.
Finland, Norway, Sweden, Denmark, and Germany are employing new and unusual ideas in their icebreaking vessels. Recurrent needs of keeping waterways and harbors free of ice in the wintertime for shipping have resulted in a great deal of research and experimentation in icebreaking in these countries.
For our own icebreaking problems there seems little doubt that our icebreaker construction program is inadequate. Too long have we had to wait for the benefits to be derived from improved materials, better construction techniques, and lessons learned from operating experience. Too long have our icebreakers been relegated as second class ships when building funds are limited.
It is high time that we take a hard, calculating look at what kind of ship will best serve our icebreaking requirements, one which will be more capable, more efficient, but less prone to damage. Extensive studies and tests in hull forms and propellers should be conducted. Innovations incorporated in the latest foreign icebreakers, particularly with regard to the unique advantages offered by nuclear power, should be reviewed.
Icebreaker design has progressed a long way since the first time an ice-clearance ship was envisioned, though, admittedly, it is still far from the ultimate craft yet in this respect. No icebreaker in the world will ever be powerful enough to move some ice, yet a better icebreaker will move far more ice than a run-of- the-mill one. We should insist, therefore, that we have the best icebreakers that can be built now for the jobs on hand and for those that beckon. Anything less is compromise.