United States R-class submarine

The R-class submarines were a class of United States Navy coastal patrol submarines active from 1918 until 1945. With the first of the class laid down following the American entry into World War I, they were built rapidly. Although R-15 through R-20 were completed July–October 1918, they did not serve overseas, and the bulk of the class were not completed until after the Armistice. As had been the usual practice in several of the preceding classes, design and construction of the 27 boats of this class was split between the Electric Boat Company and the Lake Torpedo Boat Company. Both designs were built to the same military operational specifications, but differed considerably in design and detail specifics.^[4]

Boats R-1 through R-20, also referred to as the R-1-class, were designed by Electric Boat and built by the company's subcontractor yards Bethlehem Quincy and Bethlehem San Francisco. These single-hull boats were structurally similar to the preceding O-class, but larger and therefore with more powerful machinery to maintain the required speed. Electric Boat departed from their traditional rotating bow cap that acted as the muzzle doors for the torpedo tubes. All submarines from the R-class forward built by this company would have individual muzzle doors.^[5] For the first time in a US submarine class, 21-inch (533 mm) torpedo tubes were fitted, a tube diameter that is still standard worldwide. A more powerful non-retractable 3-inch (76 mm)/50-caliber deck gun replaced the retractable 3-inch/23-caliber gun found on previous classes.^[6]

Boats R-21 to R-27, also referred to as the R-21-class, which were slightly smaller and faster than the Electric Boat design, were designed and built by the Lake Torpedo Boat Company. Simon Lake finally gave up on his patented zero-angle (aka "even-keel") diving method with midships-mounted diving planes, and adopted the Electric Boat style angled diving method using bow and stern mounted diving planes. The Lake-style flat shovel stern with ventrally mounted rudder, diving planes, and propellers were retained for this class.^[4] There is conflicting information as to what size torpedo tubes were mounted in the Lake boats, with authoritative references by Gardiner^[6] and Friedman^[1] disagreeing as to whether they were equipped with 18-inch (450 mm) torpedo tubes or the 21-inch tubes of the Electric Boat design. They were equipped with the same 3-inch/50-caliber deck gun as the Electric Boat design. At least one boat, R-22,^[7] was fitted with an expanded bow buoyancy tank that gave it a humped appearance. This was done to improve surface sea keeping. Unlike the Electric Boat design group, most of which survived to serve in World War II, the Lake boats were scrapped in 1930, as part of the Navy's compliance with the London Naval Treaty. The Lake company's demise in 1924, and poorly regarded design features, also contributed to this.^[6][4]

Most of the Electric Boat design group spent the 1920s in the Pacific, operating out of San Diego and Hawaii. In 1921, one member of this group, R-14,^[8] was stranded at sea in the Pacific, off Hawaii, when it ran out of fuel during a search and rescue operation. The boat rigged makeshift sails and sailed 140 nmi (260 km; 160 mi) to Hilo, Hawaii.^[9] The Hawaii-based boats returned to the mainland, on 18 January 1931, and were decommissioned to reserve status, at the Philadelphia Navy Yard, in 1931.

In the aftermath of S-4's disaster in 1927, all of the EB design boats were modified for greater safety. A motor room escape hatch was added, the motor room being the after most compartment. The tapered after casing became a step as a result of this modification. The boats also received salvage air connections and mating surfaces around topside hatches to allow the McCann Rescue Chamber to rescue trapped crewmen.^[4]

As the war emergency in Europe became more urgent, most of the boats were recommissioned in 1940, conducting patrols in the Caribbean, or being used as sonar targets at Key West, Florida. They also patrolled between Submarine Base New London, in Connecticut, and Bermuda. At least two R-boats unsuccessfully fired torpedoes at German U-boats on the Bermuda patrols.

During the war, several R class boats operated out of Key West, being assigned to support the Fleet Sonar School. They served primarily as sonar targets for training crews of destroyers and destroyer escorts in anti-submarine warfare. They also conducted patrols in the Florida Strait, and the Yucatán Channel.

Three boats, R-3, R-17, and R-19, were transferred to the United Kingdom's Royal Navy, as HMS P.511, HMS P.512, and HMS P.514 in 1941-1942. P.514 was lost on 21 June 1942, in a collision with the Canadian minesweeper HMCS Georgian due to being mistaken for a U-boat. R-12 was lost on 12 June 1943, while underway off Key West. While the cause of her loss has never been definitively determined, when her wreck was found by the in 2010, by the Lost 52 Project, it was suspected that the old boat suffered from a hull failure in the forward battery compartment.^[10]

Between May and September 1945, the 15 remaining R boats in the US Navy were decommissioned and subsequently scrapped.

Electric Boat built four variants of the R class for the Peruvian Navy (BAP R-1 to R-4). Built after World War I, using materials assembled from cancelled S-class submarines, they were refitted in 1935–1936 and 1955–1956, and renamed Islay, Casma, Pacocha, and Arica in 1957. These were the first submarines built directly by Electric Boat, at their newly established shipyard along the Thames River, in Connecticut.^[11] They were discarded in 1960.

In December 2020, the remains of R-8 were discovered off the coast of Ocean City, Maryland.^[12] The vessel sank there in 1936, after being used for target practice by bomber aircraft.

The 27 submarines of the R class were:

• NavSource early diesel submarines page
• DiGiulian, Tony Navweaps.com early 3"/50 caliber guns