USS Tusk (SS-426) - Shakedown and GUPPY Conversion

Shakedown and GUPPY Conversion

Tusk completed her shakedown cruise in the southern Atlantic with a round of goodwill visits to Latin American ports. She called at Rio de Janeiro and Bahia in Brazil, Curaçao in the Netherlands West Indies, and at Colón in the Panama Canal Zone before returning to New London, Connecticut, in June. For the next year, she conducted operations along the East Coast between New London and Wilmington, North Carolina. During the first month of 1947, Tusk participated in a fleet tactical exercise in the Central Atlantic. A three-month overhaul at Philadelphia, Pennsylvania, followed by oceanographic work along the Atlantic shelf in conjunction with Columbia University and the Woods Hole Oceanographic Institution occupied her until October 1947 when she entered the Portsmouth Naval Shipyard for a Greater Underwater Propulsive Power Program (GUPPY) conversion.

Over the next seven months, Tusk received extensive modifications to improve her submerged performance characteristics. Four "greater capacity" batteries replaced her old larger ones. Her hull became more streamlined—the anchors were recessed into the hull and the propeller guards were removed—to improve her overall hydrodynamic design for underwater operations. Her sail was streamlined and enlarged to house the snorkel, a device added to allow her to operate on diesel power at periscope depth and to recharge her batteries while running submerged. All of these changes helped to convert Tusk from simply a submersible surface ship into a truer submarine. They increased her submerged range; and, though she lost about two knots in surface speed, her submerged speed increased from just under 10 knots (19 km/h) to about 15 knots (28 km/h).

The newly converted submarine returned to active duty early in the summer of 1948. She conducted her shakedown training and made a simulated war patrol to the Panama Canal Zone in June and July. She returned to the United States in August and visited the United States Naval Academy at Annapolis, Maryland, where her presence allowed about 1000 fourth-classmen to see at firsthand the latest development in submarine design. That fall and winter, Tusk resumed normal operations, participating in exercises with other United States and NATO forces. She ranged from the Caribbean Sea in the south to above the Arctic Circle in the north. The beginning of 1949 brought a more restricted radius of operations. During the first six months of that year, she served with Submarine Development Group 2 based at Newport, Rhode Island. In July, Tusk rejoined the multinational forces of NATO for another round of exercises in the North Atlantic. During these exercises, she visited Derry, Northern Ireland, and Portsmouth, England.