DD-364 Mahan

The welded steel destroyers of the Mahan class were was 341.3 feet long overall, with a waterline length of 334 feet, a 34.8-foot beam, a 9.9-foot draft, and a 1,726-ton displacement. The twin screws were driven by General Electric geared turbines, which were powered by four Babcock and Wilcox, oil-burning, Express boilers. The ship's plant was rated at 46,000 shaft horsepower at 37 knots. Armament consisted of a main battery of five 5-inch/38 caliber guns and three quad 21-inch torpedo tubes mounted on deck. They additionally carried four .50 caliber machine guns, two depth charge tracks, and "K"-type depth charge projectors.

Prior to World War II the United States focused considerable attention on destroyer design and construction; in 1922 it possessed the largest destroyer fleet in the world. The basic pattern for prewar destroyers was set with the Farragut class destroyers of 1934; they were followed by larger "leader" destroyers of the Porter class of 1935-1936. The next class, and the first to introduce "extreme steam conditions" was the Mahan class.

In March 1935, the Navy General Board met to discuss military characteristics of destroyers. The Farragut-class, first commissioned in 1934, was deemed ?satisfactory, but, of course, it is necessary to make improvements in new construction where practicable in order to not fall behind in design progress. These improvements were found in the follow-on Mahan-class 1500-tonners. At the completion of the current destroyer building program, including both the 1500-ton and 1850-ton classes, the Navy would have seven squadrons of 1500-ton destroyers and ten 1850-ton leaders, one for each squadron and three spares.

Armament changes included the movement of torpedo tubes from the centerline to the wings, an extra set of quadruple torpedo tubes, dual purpose guns verses the single purpose guns installed on the first two ships, and the installation of protection for vital spaces on the ship against .50 caliber machine gun attacks and fragments.

The Mahan destroyers incorporated prototypes of a new generation of destroyer machinery, which combined increases in pressure and steam temperature with a new type of lightweight, fast-running turbine. Thus was introduced a class whose long endurance was so important for Pacific warfare. The Mahan class was also important in that additional above-the-waterline 21-inch torpedo tubes were added and gun crew shelters were built for the superimposed weapons fore and aft for the first time. The Mahan destroyers were the first destroyers fitted with emergency diesel generators. Eighteen of these destroyers were built between 1935 and 1936, among them, Lamson (DD-367).

Lamson (DD-367)

Lamson was ordered retained in inactive status on November 15 "in view of experimental tests" and was sent to San Diego on November 29. At year's end, the destroyer returned to Pearl Harbor, where it was prepared for Operation Crossroads.

Lamson steamed from Pearl on May 21, 1946, for Bikini. The destroyer sailed with Submarine Division 111, made up of Skipjack, Tuna, Skate, and Searaven, also bound for Crossroads. On the afternoon of Thursday, May 30, 1946, Lamson arrived at Bikini and was anchored at "Berth 142" in 21 fathoms of water. According to the ship's log for June 30, 1946, the main engines were secured on 12 hours notice, the gyro was secured, and boiler No. 4 alone was lit for auxiliary purposes. That morning the crew was mustered, evacuated to USS Henrico (APA-45), and the last inspection of the ship was made. In the afternoon the fires were allowed to die under the No. 4 boiler, the engineering plant was secured, and condition "affirm" was set: "ship is secured throughout" before the last of the crew departed.

The log reported on Monday, July 1, "Anchored as before. 0902 Bomb for Test 'ABLE' was detonated. 0930 Lamson was reported as capsized, with her keel in the air, as a result of the atom bomb detonation. In the early afternoon the Lamson rolled onto her port side and sank stern first in 21 fathoms of water." Lamson was anchored approximately 700 yards abeam and slightly aft of the actual zeropoint for the Able bomb's detonation.

Loaded with 50 percent of its fuel and ammunition, Lamson was badly damaged by the Able test burst, which tore off the light topside superstructure, stacks, and mainmast, and badly smashed the bridge. Photos taken 12 seconds after the burst show the destroyer upright, but with heavy superstructure damage; a second photograph, taken nearly six minutes after the burst, shows the same. At 9:40 a.m. a reconnaissance plane, PBM Charlie, noted the destroyer was on its beam ends, "on her starboard side with her bridge structure underwater, and the port side of her bottom above the surface. A large oil slick...trailing to leeward." Lamson remained afloat at least until 2:00 p.m., when PBM Charlie departed the lagoon; the vessel capsized to starboard and sank (after floating bottom up) sometime between 2:00 p.m. and 5:00 p.m., five to eight hours after the blast; at 5:00 p.m., USS Reclaimer (ARS-42) made a quick tour of the lagoon and found "no trace of the Lamson."

Divers found the ship resting on its starboard side; "the stern was lying in a hole which makes it appear that the ship went down stern first, pivoted around and ended up heading southwest on the bottom." Navy reports made just after Able indicate that "the portion of the stern aft of frame 178 has twisted counterclockwise until the sheer strakes are separated about three feet. This rotation appears to pivot about the centerline of the deck." A "large dent" was noted in the bottom shell plating extending from the port propeller guard to the centerline, with an 18-inch-deep "wrinkle" in the main deck plating at the stern, with another wrinkle "of varying depth and width in the port side shell plating. It is 2.5 feet deep and 18 inches wide at frame 170 and tapers to nothing at frame 130. The sheer strake appears crushed between frame 70 and 80." The starboard side was not examined because the destroyer was lying on it.

Damage topside included the missing stacks and mainmast, "badly damaged" light superstructure, and the foremast, which was bent aft at a 90-degree angle. "At frame 70 a Z door and frame are blown out. The port side of the deckhouse aft of mount 2 is opened up top and bottom for a short distance fore and aft." The guns remained in their mounts, "at maximum elevation," and the quad 21-inch torpedo tubes "are apparently intact. Only one torpedo is in the tubes and it is broken and hanging there." The depth charge racks "are twisted and torn almost beyond recognition," with "a large number of depth charges around the bottom aft. The special weapon NORD 5130 was not in its chocks on the stern and could not be located."

Lamson was decommissioned on July 29 and stricken from the Navy Register on August 15, 1946.