

USS Sailfish (SSR-572) and USS Salmon (SSR-573), were the first purpose-built radar picket submarines and were commissioned in 1956. In these boats, the search antenna was retractable into a fore-and-aft recess in the top of the sail. In this bow-on view of Salmon, the search antenna is deployed athwartships, and the height finder on its pedestal is visible just to the right of the sail. As a direct consequence of the Navy's growing need for long-range air defense in the final phases of World War II, U.S. submarines gained an improbable new mission as early-warning radar pickets that expanded dramatically during the early Cold War. The resulting series of distinctive submarine classes eventually culminated in the largest nuclear-powered submarine the United States had ever built. And then inside of a year or two, they were all gone. It's an interesting story. Defending Against

the "Divine Wind"

In the closing months of the Pacific war, Japan's desperate use of kamikaze aircraft - suicide planes - in its last-ditch defense of the home islands inflicted serious damage on the gathering Allied fleet. In attempting to counter this new threat during the invasion of Okinawa in April 1945, the U.S. Navy deployed lines of destroyers as "radar pickets" across the threat axis at some distance from their task group centers. Although these distant ships provided timely early warning of Japanese air attacks and significantly reduced the toll taken of major combatants, they themselves proved exceptionally vulnerable to kamikaze tactics, and twelve were sunk.

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.



(left) The first full-blown radar-picket conversions - of USS Requin (SS-481) and USS Spinax (SS-489) - were completed in 1946. This stern view of Spinax shows the cause of most of the technical difficulties found with this earliest design: both the search radar and the height-finder were located down aft at deck level. Subsequently, both Requin (shown here) and Spinax were given so-called MIGRAINE II conversions, which moved the air-search radar to a pedestal above the aft end of the sail but left the height finder in its original position. Post-War Developments -

Project MIGRAINE

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) (see footnote) 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. [Editor�s Note: See �Regulus � America�s First Sea-borne Nuclear Deterrent,� in the Spring 2001 issue of UNDERSEA WARFARE.] By this time, the Cold War with the Soviet Union was in full swing, and air defense of U.S. carrier battle groups on potential strike missions near the Russian landmass generated a requirement for even more submarine radar pickets. Eventually, six more World War II submarines � all Manitowac-built USS Gato (SS-212)-class boats � were chosen for the more drastic MIGRAINE III SSR conversion. Because experience had shown that even the newer SSR configurations were seriously cramped, the final MIGRAINE design called for cutting the boats in two and inserting a 24-foot �plug� to get additional room for an expanded CIC and electronic spaces forward of the main control room. Even so, the MIGRAINE IIIs also had to sacrifice their after torpedo tubes for more berthing space, but they were fitted with a larger, streamlined sail, with the BPS-2 search radar mounted aft of the periscopes and other masts. An AN/BPS-3 height-finder radar on a pedestal just behind the sail and an AN/URN-3 TACAN beacon on the afterdeck completed the installation. The six MIGRAINE III boats � USSs Pompon (SSR-267), Rasher (SSR-269), Raton (SSR-270), Ray (SSR-271), Redfin (SSR-272), and Rock (SSR-274) � were all converted at the Philadelphia Navy Yard between 1951 and 1953 � giving the Navy a total of ten radar picket submarines to face the growing Soviet threat just as the Korean War was drawing to a close. In the MIGRAINE I conversions, both search radar and height-finder were moved to pedestals abaft the sail. This is USS Tigrone (SSR-419), converted in 1948; USS Burrfish (SSR-312) followed in 1949. The small antenna farthest aft is for an aircraft homing beacon. New-Construction SSRs

and Cold War Operations

To the MIGRAINE units were added two new-construction boats, USS Sailfish (SSR-572) and USS Salmon (SSR-573), designed from the keel up as radar pickets and laid down at the Portsmouth (New Hampshire) Navy Yard in December 1953 and March 1954, respectively. With a length of 350 feet and a surface displacement of over 2,300 tons, these were among the largest conventional submarines ever built by the United States. Because it was assumed that they would spend most of their time on the surface, Sailfish and Salmon were given substantial reserve buoyancy and hull forms optimized for surface performance. On each, the BPS-2 air-search radars could be rotated into a fore-and-aft position for retraction into the large sail fairwater, but just as in the MIGRAINE III boats, the BPS-3 height finder was mounted on a pedestal abaft the sail. The two new SSRs were both commissioned in mid-1956, giving a total of 12 radar pickets, but since the earliest of the MIGRAINE boats were reaching the end of their service lives, that total would soon drop. Eventually, seven SSRs (Requin, Tigrone, Burrfish, Pompon, Ray, Redfin, and Sailfish) were assigned to the Atlantic Fleet and operated nominally in the Caribbean and North Atlantic, with regular participation in NATO exercises and periodic deployments to the Mediterranean as part of the U.S. 6th Fleet. The five remaining (Spinax, Rasher, Raton, Rock, and Salmon) went to the Pacific Fleet and operated off western North America and in WESTPAC deployments to 7th Fleet. Although the SSRs became key participants in fleet air defense as early-warning pickets and CAP controllers 50 to 100 nautical miles in front of typical Cold War carrier battlegroups, their overall effectiveness was frequently hampered by their relatively modest surface speeds, particularly when task-group course changes required rapid repositioning. Even Sailfish and Salmon, the fastest of the type, could only make 20 knots on the surface, little better than the older fleet boats. Thus, the accelerating development of submarine nuclear power - and the debut of USS Nautilus (SSN-571) in early 1955 - appeared to offer a welcome solution to this operational problem. The Ultimate Radar Picket Submarine - USS Triton

Consequently, the Navy laid down what was intended as the first of a series of nuclear-powered radar picket submarines in May 1956. This was USS Triton (SSRN-586), which at 448 feet long and nearly 6,000 tons surface displacement, emerged as the longest U.S. submarine ever built until the appearance of the USS Ohio (SSBN-726) class in the early 1980s. Triton was unique among U.S. submarines in carrying a propulsion plant with two nuclear reactors, each an S4G rated at 22,000 horsepower. She was also the last U.S. submarine to have a conning tower inside the sail, twin screws, and an after torpedo room. Like Sailfish and Salmon, she was optimized for high surface speed - with a knife-like bow and ample reserve buoyancy - and reportedly, she exceeded 30 knots on her trials. Although like the most recent SSRs, Triton mounted her air-search radar on the sail where it could be stowed within the fairwater for submergence, her newer AN/SPS-26 was scanned electronically in elevation, so no separate height-finding radar was required. With three deck levels beneath the sail, there was ample room for dedicated air-control facilities just below the control room/attack center. Triton was commissioned in November 1959 with the decorated World War II submarine skipper - and later distinguished naval author - CAPT Edward L. Beach, in command. For Triton's maiden voyage/shakedown cruise, Beach was ordered to attempt the first submerged circumnavigation of the globe, and the ship departed New London on 16 February 1960, not to return until 10 May, 84 days and 41,500 nautical miles later. This unprecedented success brought significant international prestige to the nation and the Navy, and by maintaining a steady speed of 21 knots for nearly three months, Triton firmly established the endurance and reliability of nuclear propulsion. In recognition, President Dwight D. Eisenhower awarded the ship and her crew a Presidential Unit Citation after their return. Triton joined 2nd Fleet in August 1960, and soon thereafter, she deployed to European waters to assume her role as a radar picket in a series of NATO exercises. And then� the bottom dropped out of her primary mission. The Passing of the Pickets - and the Rest of the Story

With the successful introduction of carrier-borne early warning aircraft in 1958 - first the Grumman E-1B Tracer, and then the successor E-2 Hawkeye in 1964 - the requirement for surface radar pickets soon faded, and the SSR/SSRN mission was quickly phased out. Thus, in March 1961, Triton was reclassified as an attack submarine (SSN) and overhauled at Portsmouth between 1962 and 1964 to refuel her reactors and convert her for a new role. Even though she was too large to be effective as an attack boat, Triton - now SSN-586 - served gamely at Norfolk as flagship of COMSUBLANT until June 1967, but nonetheless she had become an expensive white elephant. Although plans were floated to use her large, surviving CIC space as an alternative national emergency command post, these never came to fruition, and when a planned 1967 overhaul was cancelled because of defense cutbacks, her days were numbered. Triton was subsequently inactivated and then decommissioned in May 1969 - the first nuclear-powered submarine to be withdrawn from service. She is now in storage at the inactive ship facility in Bremerton, Washington, awaiting final disposal by the Nuclear Ship and Submarine Recycling Program.

The first - and only - nuclear-powered submarine laid down as a radar picket was USS Triton (SSRN-586), commissioned in November 1959. Powered by two reactors, and at that time the largest submarine in the world, Triton made a submerged circumnavigation of the globe on her maiden voyage in early 1960. Within a year of that historic event, however, the radar-picket mission had been supplanted by airborne early warning, and she was converted to an SSN soon after. Similarly, 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; the last were Sailfish and Salmon. Although two of the MIGRAINE III boats were put out of service and scrapped almost immediately, the remainder were reclassified as conventional attack boats (SS) or as auxiliary general submarines (AGSS) for non-combat duties, and they survived for "twilight careers" that lasted as late as 1978. The longest-lived was Sailfish, which was decommissioned in September of that year and which still remains laid up and afloat at Bremerton. Several of the others served as Naval Reserve training hulks after decommission, and five were eventually sunk as targets, most recently Salmon in 1993. Tigrone was re-commissioned in March 1962 and, as an AGSS, played a major part in developmental testing for several passive sonar systems before she was finally put out of service in 1975. Similarly, Redfin - as AGSS-272 - became a test platform for the pioneering inertial navigation systems required by the Polaris SLBM program. She was then decommissioned in May 1967 and scrapped four years later. Burrfish had an interesting aftermath: The Canadian Navy leased the boat in 1961, renamed her HMCS Grilse (SS-71), and used her as a "live" target for anti-submarine warfare training. She was returned to the U.S. Navy in 1969 and sunk as a target that same year. 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. Dr. Whitman is the Senior Editor of

UNDERSEA WARFARE Magazine. (footnote) It is interesting to note that Requin�s first Commanding Officer was World War II submarine ace CDR Slade Cutter, and the CO who first took her to sea as a radar picket was Medal of Honor winner CDR George L. Street, III.

[See �Submarine Hero � Slade Deville Cutter� in the Fall 2000 issue of UNDERSEA WARFARE; and �Submarine Hero � George Levick Street, III� in the Fall 1999 issue.]