CLK-1 Norfolk / DL-1 Norfolk Class
The end of World War II also produced new, deadlier submarine threats. Late U-boats of the Type 21 (somewhat like the USN's postwar "Guppy" conversions, with better streamlining, more battery power, and a snorkel for charging batteries at periscope depth), and Walter type (powered when submerged by hydrogen peroxide, requiring no air for propulsion) had much higher submerged speed than wartime production models.
Postwar, the US Navy discovered that U-boats had had greater depth capability than American submarines, and the high-tech late U-boats were also deep divers. The Type XXI had a maximum depth of over 900 feet. Like the late war airborne threats, these late war submarine threats suggested that World War II type escorts were inadequate and that new kinds of antisubmarine warfare (ASW) ships would have to be created.
Building on the advanced submarine designs created by the Germans during World War II, the Navy anticipated submarines of the future going deeper, staying there longer, and moving much faster. Indeed, in reports submitted in 1949 and 1950 naval and civilian advisors suggested that advanced German U-boat technology exploited by the Soviets might present the most potent postwar naval threat to the United States. No warship of the time could effectively detect and track a submarine like the German Type 21 which could sustain a 17 knot submerged speed for at least thirty minutes.
One type was the "hunter-killer cruiser", using the new designation CLK. The Bureau of Ships developed the design from the wartime Atlanta antiaircraft cruiser. Its main features were large size and good seakeeping so that even in bad weather it could overhaul a 25-knot submarine. It was to be armed with new, trainable Weapon Able (or Alpha) ASW rocket mounts whose size and ship impact was similar to a medium caliber gun turret, as well as homing torpedoes and an elaborate sonar for targeting. All these features led to rather a cruiser-size ship, which is why BuShips picked Atlanta as the starting point.
The ship had a double bottom that went up to the second deck – clearly a cruiser rather than destroyer feature. The two machinery units were separated by 20 feet to improve survivability. The ship was finally commissioned as USS Norfolk in 1953. She had four twin 3-inch /70 turrets as "main" armament, but the four Weapon A launchers and eight torpedo tubes were really her reason for being. At 520 feet LWL and 6600 tons, this was a small cruiser even compared to its WWII prototype, with a twin 80,000 SHP powerplant that resembled the Atlanta's except that it was 1200 psi. However, compared to wartime destroyers then in service which were in the 3000 ton range, it was something more than a destroyer.
The second Norfolk (DL-1), projected as hunter-killer ship (CLK-1), was laid down 1 September 1949 by the New York Shipbuilding Corp., Camden. N.J.; launched 29 December 1951; sponsored by Miss Betty King Duckworth; and commissioned 4 March 1953, Capt. Clarence Matheson Bowley in command. The first major U.S. warship built since World War II, Norfolk was authorised in 1947 as an anti-submarine hunterkiller ship which could operate under all weather conditions and would carry the latest radar, sonar, and other electronic devices.
The designator CLK 1 didn"t last long. The new category was abolished in 1951, and Norfolk was redesignated as DL 1 , with the Mitscher class (formerly DD 927, a 4500 ton AAW destroyer of about the same date as Norfolk) becoming DL 2-5. The new designator DL stood for "Destroyer Leader" – a term dating from before World War I, referring at that time to a destroyer flotilla leader. But, in the postwar US Navy, the DL designator was associated with the term "frigate", and meant a type intermediate between destroyer and cruiser, functioning as a multi-role task group escort. This designator continued to be used for mainly AAW battle group escorts into the 1970's. The confused terminology did not conceal the reality that a more cruiser-like ship was needed for both fleet AAW and ASW defense in the postwar era.
As a large destroyer leader designed on a light cruiser hull, she could carry a greater variety of detection gear than a destroyer. By 1959 Norfolk's 8 3" 70 cal. guns had been replaced by 8 3" 50 cal. guns and her 20mm. battery had been removed. In 1960 the addition of an ASROC launcher enchanced her antisubmarine capabilities.
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