Subsequently, the ship's weight and forward motion combine to fracture the ice. The upward angle of Polar Star 's bow is designed so that the hull rides up onto the ice surface during icebreaking operations. Propeller issues continued through 1977-1988, leading Coast Guard to invoke the warranty clause of the Lockheed Shipbuilding and Construction Company. While the centerline propeller functioned satisfactorily, it too displayed evidence of incipient failure of the link bearings. Removal of the wing propellers and opening of the hubs revealed massive failures of the links, link bearings, and drive pins. The starboard controllable pitch propeller failed, followed up shortly by the same type of failure on the port propeller. In May and early June 1976 Polar Star conducted ice trials in the Arctic regions during Arctic West Summer (AWS76) operations.
#Starmade fleet portable
Later upgrades allowed it to serve as a scientific research platform with five laboratories, additional space for seven portable laboratories on deck and accommodations for up to 35 scientists. The 13,000-ton (13,200-metric ton) Polar Star is able to break through ice up to 21 feet (6.4 m) thick by backing and ramming, and can steam continuously through 6 feet (1.8 m) of ice at 3 knots (5.6 km/h). The curved bow allows Polar Star to ride up on the ice, using the ship's weight to break the ice. The portion of the hull designed to break ice is 1.75 inches (44 mm) thick in the bow and stern sections, and 1.25 inches (32 mm) thick amidships. Polar Star's shell plating and associated internal support structure are fabricated from steel that has especially good low-temperature strength. The diesel-electric plant can produce 18,000 shaft horsepower (13 MW), and the gas turbine plant a total of 75,000 shaft horsepower (56 MW). Each shaft is connected to a 16-foot (4.9 m) diameter, four-bladed, controllable-pitch propeller. The ship's three shafts are turned by either a diesel-electric or gas turbine prime mover. In August 1971 the Secretary of Transportation announced awarding of a contract to Lockheed Shipbuilding and Construction Company of Seattle, Washington, "to build the world's most powerful icebreaker for the US Coast Guard," Polar Star, the first of two "Polar-Class" icebreakers. Replacement ships for what is called the Polar Security Cutter program have been ordered for a new generation of USCG icebreakers. The Coast Guard's only other icebreaker, USCGC Healy, despite being classified as a "medium icebreaker", is actually larger than 'Polar Star' (13,623 LT versus 16,000 LT). After Polar Sea was deactivated in 2010, Polar Star became the US's only heavy icebreaker. Homeported in Seattle, Polar Star operates under the control of Coast Guard Pacific Area and coordinates her operations through the Ice Operations Section of the United States Coast Guard. Commissioned in 1976, the ship was built by Lockheed Shipbuilding and Construction Company of Seattle, Washington along with sister ship, USCGC Polar Sea. USCGC Polar Star (WAGB-10) is a United States Coast Guard heavy icebreaker. Three shafts controllable-pitch propellers.
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