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The Coast Guard Cutter Polar Star and its sister ship, the Polar Sea, are the world's most powerful non-nuclear
icebreakers and operate from the Coast Guard Support Center at Pier 36, Seattle, Washington.
Polar Star's primary missions are scientific support in the arctic and Antarctic and ice escort of shipping and logistics support for U.S. Government interests in both polar regions. In addition to providing support to scientific stations, the Polar Star is equipped to function as a major scientific platform. We have laboratories, offices, and sleeping quarters which can support 20 scientists and technicians in a variety of programs. The Polar Star, like all Coast Guard vessels, is also prepared to perform search and rescue, law enforcement, and environmental response missions. One of the most outstanding characteristics of the Polar Star is its powerful propulsion system. Each of Polar Star's three shafts can be turned by either a diesel-electric or a gas turbine power plant. Each shaft is connected to a four-bladed, controllable pitch propeller with a 16-foot diameter. The diesel-electric plant can produce 18,000 shaft horsepower and the gas turbine plant 75,000 shaft horsepower, making the Coast Guard Polar class the world's most powerful non-nuclear icebreakers. POLAR CLASS ICEBREAKERS POLAR STAR's propulsion is provided through three shafts that are turned by either a diesel-electric generator/motor or a by gas turbine/reduction gear system. Each shaft has a 16 foot diameter, four-bladed, controllable pitch propeller. The diesel electric plant can produce 18,000 shaft horsepower and the gas turbine plant a total of 75,000 shaft horsepower. POLAR STAR has a computerized propulsion control system to effectively manage its six diesel powered propulsion generators, three diesel powered ship's service generators, three propulsion gas turbines, and other equipment vital to the smooth operation of the ship. The extensive use of automation and low maintenance materials have significantly reduced manpower needs compared to earlier icebreakers. Though POLAR STAR is capable of breaking very thick ice, rule number one in ice breaking is, "if possible, avoid the ice". This is simply because it takes longer, consumes more fuel, and produces more "wear and tear" on the ship to batter through the ice. However, when there is ice between the ship and its destination, Polar Star can do the job. The most efficient way to break through ice is to find the weakest points and break through where less force will be required. This is usually done by exploiting existing cracks or open areas called "leads". When there are none, the ship is piloted preferably over "first year ice", which is often flat and 2-6 feet thick, depending on how severe the Antarctic winter has been. As sea ice gets older it becomes considerably stronger. With first year sea ice, most of the salts remain in tiny pockets that prevent a more rigid crystalline ice structure from forming. POLAR STAR can usually maintain a continuous speed of 3-5 knots through most first year ice. As the ice ages, the salts slowly leach out, leaving behind much stronger ice. This "multi-year" ice is very distinctive. It has a deeper blue color as compared to the whiter shade characteristic of first year ice. Its hardness is even more distinctive, and causes the ship to slam and shudder dramatically whenever multi-year ice is encountered. More often than not, the ship has to "back and ram" to make progress through multi-year ice. When POLAR STAR is stopped by the ice, the cutter will back down between one half and two ship lengths (200-800 feet) through the track cut in the ice behind it. Polar Star then uses its engines to create as much forward momentum as possible before coming into contact with the ice where it was previously stopped. The momentum of the ship will carry the cutter up higher on the ice, and push it ahead with more force to break through. This process is repeated as many times as is necessary to get through the heavy area, but consumes much greater amounts of time and fuel. POLAR STAR has sufficient hull strength to absorb high powered rams into the ice. The hull plating, which is 1-3/4 in. thick at the ice belt, and associated internal support structure are fabricated from steel that has especially good low-temperature strength. The shape of the hull is designed to maximize ice breaking by efficiently combining the forces acting on the ship. The curve of the ice breaking bow allows POLAR STAR to first ride up on top of the ice, then the bow is levered downward by gravity through the ice like a giant sledgehammer, as the stern is forced upward by the added buoyant forces created there by the bow's upward inclination on the ice. This "one-two" punch brings an incredible amount of the ship's 13,000 tons to bear on the ice. POLAR STAR has other unique features designed to aid in ice breaking. An installed heeling system can rock the ship to prevent getting stuck in the ice. Fuel tanks which can carry over 1.3 million gallons of fuel provide the POLAR STAR with 60-150 days of endurance. A central hydraulic system operates cranes, boat hoists, and the anchor system. Polar Star also carries two H-65 helicopters during major deployments, which are used to carry out scientific support, ice reconnaissance, cargo transfer, and search and rescue as required. The ship has five laboratories and has berthing to accommodate up to 20 scientists. The cranes and work areas give scientists the capability to do at-sea studies of geology, oceanography, sea-ice physics, and several other science disciplines. SHIP'S ORGANIZATION The Commanding Officer, or "CO" is addressed as "Captain". His authority on board is nearly absolute in accordance with long standing maritime traditions and Coast Guard Regulations. The Captain is ultimately responsible, and totally accountable for the ship, it's mission, and her crew. The Executive Officer, or "XO", is second in command and is directly responsible to the CO for the day-to-day internal operations of the vessel. The ship is organized into five departments: Operations, Engineering, Deck, Supply, and Aviation. Each Department is then subdivided into Divisions. Department Heads are officers who report directly to the XO. Division Officers are responsible for their assigned division and report directly to their Department Head. Operations in the remote, hazardous and unforgiving Polar regions make it necessary for the crew of POLAR STAR to be highly self-sufficient. The crew consists of personnel trained in navigation, seamanship, engineering, aviation, welding, machinery, electronics, boat handling, fire fighting, damage control, diving, medicine, meteorology and nearly every other kind of special skill and support that could possibly be needed. 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Source: U.S. Coast Guard Cutter Polar Star |
