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AGSS-569 Albacore 1962-1967 - Phase IV

In 1962, Albacore went into Phase IV. In 1962, she received a newly developed DIMUS sonar system and, on 7 December of that year, work began on her fourth major conversion which included the installation of concentric contra rotating propellers, of a high-capacity silver-zinc battery, and of a larger main motor. New radio equipment, BQS and BQR sonars, an emergency recovery system, and a new main ballast tank blow system were also added. After the work was completed in March 1965, Albacore prepared for deployment to Florida waters to study the results of her changes. She returned to Portsmouth on 8 October and continued to evaluate her capabilities under the new configuration. On 1 August, she reentered the Portsmouth Naval Shipyard to replace the silver-zinc battery and to shorten the distance between the contra-rotating propellers-work which lasted into August 1967.

More powerful machinery, with contra-rotating propellers, were installed, giving her a greater underwater speed. During this period, the single propeller was replaced by a 10-foot diameter, 7-bladed forward propeller, in tandem with an 8-foot diameter, 6-bladed aft propeller. These propellers are concentric -- one left-handed and one right- handed, separated by a short spindle. The two screws turned in opposite directions. Still and motion picture cameras were installed to determine the cavitation characteristics of the various propeller sizes and spindle lengths tested.

The spacing between these two propellers was set at 10 feet and a second 7,500-SHP motor was added to drive the second screw. Continuous testing in this test series saw the shortening of the distance between the two screws during an overhaul between August 1966 and August 1967 and further shortening in January 1968. The separation distance was decreased to five feet which proved optimal for propulsion efficiency.

In February 1966, when most submarines were averaging speeds of 10 knots submerged, the Albacore was credited with the world record of 33 knots underwater. In an attempt to reach similar speeds in an operational boat, USS Jack (SSN-605), commissioned in 1967, incorporated counter-rotating propellers in its design. But Jack was never able to reach Albacore's speed, and the counter-rotating propeller system would not be used in any future submarine classes.

Two more modifications were made to the boat in Phase IV. New high capacity silver-zinc batteries replaced the traditional lead-acid type. These batteries allowed Albacore to operate longer at a high speed. The other modification was the installation of a new high pressure "emergency" ballast blowing system called "Subsafe." This would slam 3000 psi air from storage into the ballast tanks for a rapid return to the surface in the event of a power loss or other emergency.

The Submarine Force had suffered a major catastrophe while Albacore was working through Phase IV. In 1963, during deep-diving trials, USS Thresher (SSN-593) suffered a flooding casualty and was unable to blow her ballast tanks and surface, resulting in the loss of the submarine and all aboard. In response to this tragedy, an emergency blow system was installed and tested on Albacore. This new system ran a maze of piping from the air banks, through the control room and then to the ballast tanks. In the control room, the blow valves could be operated manually to expel ballast in each tank. When there was an emergency, a flip of the "chicken switch" blew all the ballast tanks and the submarine would rise rapidly to the surface.

Quartermaster Norm Bower recalls this experience, "After testing the system on the surface, we went to sea to test it while submerged. Our first test was from a depth of 100 feet and a dead stop. The blow was initiated and the boat rose rapidly to the surface. The second test was. from 300 feet. When the blow began, the boat immediately took a huge [54 degree] angle to starboard and stayed that way until we reached the surface.we did the blow from 500 feet and we shot to the surface with no problem."

Standardization and machinery tests in the Gulf of Maine during September were followed by evaluation of towed sonar arrays off Port Everglades, Fla., in October and November 1967. Then came acoustics trials in the Tongue of the Ocean, a deep channel in the Central Bahamas.

On New Year's Day 1968, the submarine returned to Portsmouth for a modification of her propulsion system which kept her in the navy yard until 19 April 1968. Then, following a month of trials in the Gulf of Maine, she headed south for evaluation of her new MONOB I and AUTEC systems and of Fly-Around-Body (FAB), Phase I, equipment on Tongue of the Ocean. The "fly-around-body" was tested in 1968. This is a sort of underwater kite which can be used to deploy antenna systems from a submarine's superstructure. She returned to Portsmouth on 24 August for AUTEC de-instrumentation and installation of FAB Phase II equipment. Then, following evaluation of this new gear in the Gulf of Maine, Albacore returned to Portsmouth on 30 September 1969 and went into reduced operating status pending the results of further studies on the feasibility of using her thereafter for further research.