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SSR-481 Requin

Since the anticipated invasion of Japan itself - scheduled for November 1945 - was expected to attract an even more intense kamikaze onslaught, the Navy high command sought to use submarines as less vulnerable radar pickets and in July 1945 ordered that 24 boats be prepared for that role by installing an approximation of a typical destroyer's radar and air-control capabilities. Since preliminary tests indicated that the standard submarine radar could not detect air targets above 10,000 feet or beyond 27,000 yards, and because there would need to be a combat information center (CIC) and appropriate communications onboard for controlling interceptors, the necessary full-blown conversions would have stretched into 1946, too late for their intended role in the invasion of Japan. As an interim measure, COMSUBPAC modified the SV air-search radars on USS Grouper (SS-214) and USS Finback (SS-230) for periscope mounting and operation at shallow submergence, and similar conversions of four other boats - including rudimentary CICs - had already begun when the Japanese surrendered in August 1945.

Even though the end of World War II eliminated the urgent need for radar picket submarines, two of the more ambitious conversions planned earlier were continued on the USS Tench (SS-417)-class fleet submarines, USS Requin (SS-481) and USS Spinax (SS-489) and completed in the fall of 1946. Although not yet classified as radar pickets ("SSRs"), both submarines mounted high-powered SR-2 search radars and SV-2 height finders directly on their afterdecks, with the radar electronics and CICs just below in the after torpedo rooms. Although a stern launching capability was still retained, the tubes had to be loaded externally. To accommodate the additional electronics, each boat received an extra motor-generator and more air-conditioning, and to provide a reference point for the combat air patrol (CAP) they controlled, homing beacons were deck-mounted on both. Despite having to discontinue radar operations whenever they submerged, Requin and Spinax were basically successful in their new roles, and they were certainly more survivable than a corresponding destroyer. However, the low deck-mounting of their antennas severely limited radar performance and attracted reliability problems from both breaking seas and salt-water intrusion into the waveguides. Below deck, having to crowd so much high-powered electronics into all available nooks and crannies brought its own share of maintenance headaches.

Thus, it was quite appropriate for the Navy's Bureau of Ships to name their follow-on design program for radar picket submarines Project MIGRAINE. In 1948 and 1949, making use of the lessons learned from Requin and Spinax, two more fleet submarines, the Tench-class USS Tigrone (SS-419) and the USS Balao (SS-285)-class USS Burrfish (SS-312), were given so-called "MIGRAINE I" conversions - and redesignated as SSRs. In this modification, the space formerly used as the crew's mess and galley was turned into a CIC, and the after torpedo tubes were removed to allow the entire after torpedo compartment to be used for berthing. Two of the forward tubes were also eliminated to make additional room for storage and equipment. More importantly, however, the two radar antennas were raised on masts, with an AN/BPS-2 search radar sprouting from the after portion of the sail, and the height finder mounted on a free-standing tower just abaft it. This put the 15-foot search antenna some 40 feet above the water, with the height finder only a little below.

At approximately the same time, Requin and Spinax were returned to the yard for upgrading of their earlier systems to a MIGRAINE II configuration that put the search radar up on a sail-mounted mast - as in MIGRAINE I - but left the height finder in its less satisfactory position down aft. Again, the after torpedo compartments were stripped of their tubes and used for both CIC space and crew berthing. Both the MIGRAINE I and MIGRAINE II boats were also fitted with AN/BPQ-2 guidance equipment for mid-course control of Regulus cruise missiles.

By early 1961, all of the conventionally-powered SSRs had ceased radar-picket operations. The first to be withdrawn were the MIGRAINE I boats, Burrfish and Tigrone, temporarily decommissioned in late 1956 and 1957, respectively.

Ironically, one of the first two SSRs survives today as a memorial. Requin was re-classified in 1959 as SS-481 - then AGSS-481 - and she remained in active service until December 1968. From 1972 to 1986, the ship was a tourist attraction in Tampa, Florida, but financial troubles led to abandonment by her operators. Subsequently acquired and lovingly restored by the Carnegie Science Center, Requin has been displayed in the Ohio River near Pittsburgh, Pennsylvania since October, 1990, and she remains one of the most popular exhibits in the Three-Rivers area.



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Page last modified: 22-07-2011 17:42:51 ZULU