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WAGB-10 Polar Class icebreakers

The Polar Class icebreakers were built for the U.S. Coast Guard to replace the aging Wind Class icebreaker fleet. The Polar Star and the Polar Sea were designed to break 6.5 feet. They had several mission in the Arctic, but until recent years most of the missions of the Polar Class icebreakers were in the Antarctic.

The rounded hull design of the Polar Star allows the vessel to pivot on its bow and swing the stern to port or starboard, helping facilitate freedom of movement when working under fast or anchored ice conditions. Another design feature of the Polar Star is the hulls ice horn. This ice horn is what allows the vessel to continuously break ice up to 6-feet thick and back and ram ice up to 21-feet thick.

Polar icebreakers onerate under the most inhospitable ocean ~onditions the world has to offer. Designed for optimum performance at low temperatures in Ice fields varying from unifomn plate ice to deep windrowed ridges, they also transit areas of intense heat, high winds, and extreme sea conditions. Their hull structure sees a variety of loads ranging from those thermally induced to concentrated ice Impact loads to those impossible to design for, such as grounding on uncharted rock pinnacles. The icebreaker designer must allow for extreme loads on the one hand, but must pay attention, like all naval architects, to detail design, with a view toward eliminating structu~al failures from more subtle causes such as elastic instability, brittle fracture, and fatigue.

The United States Coast Guard affords icebreaker support, both domestic and polar, to a variety of ship operations conducted in areas made hazardous or impassable by ice. Typical polar icebreaker missions include escort of vessels supplying outlying military or scientific stations: independent logistics support to similar survey operations and support in both polar regions.

The Polar icebreaking program objective is to provide for the traverse of polar regions by United States shipping and to facilitate support of activities of national interest in polar areas. The Coast Guard is responsible for operating and maintaining the entire national Polar icebreaking fleet.

The need has been apparent since the early 1960S for a new class of icebreaking ships to replace aging members of the fleet and to undertake more extensive duties as Coast Guard Responsibilities change and expand. In 1966 the Icebreaker Design Project was established in the Naval Engineering Division at Coast Guard Headquarters to initiate preliminary design work on a new polar icebreaker. Tbe initial thrust of the effort was toward a nuclearpowered cutter, hut this was later modified to conventional dieselelectric and finally revised to include a gasturbine mode of operation.

During the existence of the Icebreaker Design Project, its personnel delved into the significant aspects of ship design as it applied to icebreakers. Its most significant contributions to icebreaking technology were probably in the areas of hull form, powering predictions, and hull struture, the latter including material selection. By the time of the dissolution of the Icebreaker Design Project in 1969, a basic preliminary design had been developed. Hull form and principal dimensions had been defined, rough arrangements completed, a machinery plant size and type selected, a basic structural arrangement chosen, and tentative scantlings determined.

In March of 1970, these early beginnings were transferred to the existing Design Branch of the Naval Engineering Division for contract desizn development. Completion of the contract desi~n in 1971 was followed by bid solicitation and award of a contract to Lockheed Shipbuilding and Construction Company, Seattle.

As reported during hearings before the Merchant Marine Subcommittee, Senate Committee on Commerce in March 1972, the Coast Guard plans were to replace six "Wind Class" ships with four new icebreakers, thus giving them five ships for polar work. Funding for the first new ship was provided in the fiscal year 1971 budget, and funding for the second ship was provided in the fiscal year 1973 budget.

The Coast Guard obtained outside assistance in the form of 28 contracts totaling $980,500 for icebreaker studies. These efforts included items such as model testing, weight analyzing, arrangement and layout of vessel, structural analysis for icebreaking, vibration study, and a polar region study. The Coast Guard prepared a listing of functional specifications available to prospective bidders and for use by the construction contractor in preparing detailed design and working drawings.

The prime contractor for the icebreaker ships was Lockheed Shipbuilding and Construction Company, Seattle, Washington. For the first ship, selection of the contractor was made on the basis of price competition, and award was made under a firm-fixed price contract. The second ship was placed with the same contractor with a firm-fixed price to be negotiated. Procurement of the first ship was awarded by firm-fixed price contract for $52.7 million in August 1971. As of December 31, 1973, contract changes had increased the price to $52.9 million. A ceiling price of $53.75 million was establfshed for the second ship in January 1973. The price had not yet been definitized, and the contractor's proposal was for $60.5 million.

CGC POLAR STAR (WAGB10) is a United States Coast Guard Heavy Icebreaker. Commissioned in 1976, the ship was built by Lockheed Shipbuilding and Construction Company of Seattle, Washington along with her sister ship, POLAR SEA (WAGB11)

POLAR STAR's three shafts are turned by either a diesel-electric or gas turbine power plant. Each shaft is connected to a 16-foot(4.9-meter) diameter, four-bladed, controllable-pitch propeller. The diesel-electric plant can produce 18,000 shaft horsepower(13,425 kilowatts) and the gas turbine plant a total of 75,000shaft horsepower (55,925 kilowatts). Along with POLAR STAR's sister ship POLAR SEA, she is one of the largest ships in the US Coast Guard and the world's most powerful non-nuclear ships.

POLAR STAR has other unique engineering features designed to aid in icebreaking. An installed heeling system can rock the ship to prevent getting stuck in the ice. The system consists of three pairs of connected tanks on opposite sides of the ship. Pumps transfer a tank's contents (35,000 gallons, 133 kiloliters) to an opposing tank in 50 seconds and generate 24,000 foot-tons (64,800 kilowatt-seconds) of torque on the ship. That goes a long way in rocking POLAR STAR loose from any tight spots.

POLAR STAR carries two helicopters during major deployments. They support scientific parties, do ice reconnaissance, cargo transfer, and search and rescue as required.

POLAR STAR has a variety of missions while operating in polar regions. During Antarctic deployments, our primary missions include breaking a channel through the sea ice to resupply the McMurdo Research Station in the Ross Sea. Resupply ships use the channel to bring food, fuel, and other goods to make it through another winter. In addition, to these duties, POLAR STAR also serves as a scientific research platform with five laboratories and accommodations for up to 20 scientists. The "J"-shaped cranes and work areas near the stern and port side of ship give scientists the capability to do at-sea studies in the fields of geology, vulcanology, oceanography, sea-ice physics and other disciplines.

POLAR SEA was commissioned in 1978, and has operated in the Arctic Ocean since 1979. The ship was first involved in a series of pioneering polar marine transportation studies off Alaska, and then conducted interdisciplinary science off the northeast coast of Greenland. During a science expedition, POLAR SEA and the Canadian Coast Guard Ship LOUIS S. ST-LAURENT made the first Pacific to Atlantic crossing of the Arctic Ocean; navigating through 2300 miles of Arctic ice. The expedition greatly contributed to knowledge of previously unexplored areas of the Arctic Ocean and the role the polar ocean plays in global environmental change.

The two Polar-class icebreakers were designed to carry out a range of missions in the Arctic, including escorting non-icebreaking vessels through the ice, resupplying military and research bases, and supporting scientific operations. In recent years the role of the Polar-class vessels in research has expanded as more complex research projects and larger science teams have placed added requirements on the current icebreakers. This led to a major upgrade of their capabilities in 1987 through the Polar Science Upgrade Program, a five-year, $14 million program to enhance the scientific support capabilities of these vessels. Scientific laboratories and living areas were expanded to allow up to 32 scientists and technicians to embark on scientific cruises. Upgraded oceanographic winches, new cargo and science gear handling systems, expanded lab spaces, new oceanographic instrumentation, and new communications and satellite data acquisition systems improved the research capabilities of the Polar-class vessels.

On February 5, 1994 POLAR SEA reached 7829.9' South latitude, the southernmost point in Antarctica navigable by ship. On August 22 of the same year she was the first American surface ship to reach the North Pole. POLAR SEA has sailed all seven seas, crossed the Arctic Ocean, circumnavigated Antarctica, and visited ports in twenty-four foreign countries. As of spring 2008, POLAR SEA has made eighteen voyages to the Antarctic and nineteen voyages to the Arctic. POLAR SEA has been awarded four Coast Guard Unit Commendations, four Coast Guard Meritorious Unit Commendations, the Navy Meritorious Unit Commendation, and the Canadian Coast Guard Commissioner's Commendation.

On June 25, 2010 the Coast Guard announced the 399-foot Cutter POLAR SEA suffered an unexpected engine casualty and would be unable to deploy on its scheduled fall 2010 Arctic patrol. Polar Sea has been inactive since 2010 when it experienced a catastrophic engine failure. 2 According to a January 2017 Coast Guard assessment, the Coast Guard does not plan to recommission the Polar Sea because it would not be cost-effective.

On 30 June 2006 the POLAR STAR went into a special status "Caretaker". This caretaker status required the crew to be reduced to 34 and to keep the ship ready for a possible return to the ice. The Commandant of the U.S. Coast Guard, Admiral Thad Allen made it one of his top three priorities to find a resolution to the state of the Polar Icebreaking program. On March 11, 2010 Admiral Thad Allen, Commandant, U.S. Coast Guard, reactivated the Coast Guard Cutter Polar Star, one of Americas two polar class ice breakers. In 2013 POLAR STAR was officially reactivated and returned to the fleet and reassumed its mission.

The Polar Star, built in 1976, is well past its 30-year design life. Its reliability will continue to decline, and its maintenance costs will continue to escalate. Although the ship went through an extensive life-extending refit in 20112012, the Polar Stars useful life is estimated to end between 2020 and 2024. As USCG has recognized, the evaluation of alternative arrangements to secure polar icebreaking capacity is important, given the growing risks of the Polar Star losing its capability to fulfill its mission.

The January 2018 report estimated the remaining service life of the Polar Star as 5 years or less. In April 2018, the Coast Guard approved the Polar Star life extension project to establish requirements and evaluate the feasibility of alternatives that will achieve the requirements. This creates a potential heavy polar icebreaker capability gap of about 3 years, assuming the Polar Stars service life ends in 2020 and the lead HPIB is delivered by the end of fiscal year 2023 as planned. If the lead ship is delivered later than planned in this scenario, the potential gap could be more than 3 years.



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Page last modified: 18-04-2019 14:30:19 ZULU