In the 1930s, naval strategists foresaw a need for small anti-submarine warfare craft. These so-called "junior destroyers" would be used to protect bases and coastal shipping, releasing the bigger destroyers for fleet tasks and overseas deployment.
President Franklin D. Roosevelt was a strong advocate of the sub-chaser program and encouraged interest in the new craft. However, lack of funds precluded any subchaser construction.
When the Japanese invaded China in the fall of 1937, Roosevelt revived the subchaser program. The experimental small boat program of May 1938 called for development of two steel-hull patrol craft, or PC, types--one with diesel engines and one with a steam turbine power plant. Additionally, two prototype wood-hull subchasers, or SCs, also would be developed. The competition that ended in March 1939 attracted 11 proposals for the PC and eight for the SC.
The diesel-powered PC winner was designed by Sidney A. Vincent of Newport News Shipbuilding with the Navy Bureau of Construction & Repair (later BuShips) proposing a flush-deck design with steam turbine propulsion. The Defoe Shipbuilding Company of Bay City, Michigan, was selected to build the first two prototypes.
In 1940, BuShips recommended the flush-deck design with a diesel power plant, designating this as the 461-class PC. Fifteen different shipbuilders were involved in construction of the 359 PCs of this design.
The SC design was essentially the same as its World War I predecessor, adding upgraded anti-submarine warfare equipment, armament and propulsion systems. Luders Marine Construction and American Car and Foundry were selected to build the two prototype SCs. Fisher Boat Works was contracted to build a third SC powered with a GM Pancake Diesel power plant.
Thirty-five small boat and yacht builders nation-wide participated in construction of the 438 SCs delivered.
World War II patrol vessels did not participate in any major sea battles, but saw action in every combat zone worldwide. They performed a variety of assignments, often under extremely hazardous conditions.
In December 1941, the Navy had 77 small ships classified as patrol vessels, along with 74 Coast Guard ships, to counter the Nazi U-boat threat off U.S. coastal waters. The majority of these vessels were of World War I vintage. The rest were converted private yachts, and a few newly constructed 173-foot, steel-hull PCs and 110-foot SC patrol vessels. The PC and SC subchasers accounted for more than 790 ships in the patrol vessel fleet. A total 359 PCs and 438 SCs were constructed by various ship builders along the East and Gulf coasts, Great Lakes, inland waterways, and West Coast. Forty-four PCs and 142 SCs were transferred to U.S. allies under the Lend-Lease program and served in seven Allied navies.
The PCs were effective in protecting convoys along the Atlantic seaboard and in the Caribbean, Gulf of Mexico and south Atlantic during the critical years of 1942-1943. Relatively easy to build, the PC filled the escort gap until the destroyer escort could be produced in sufficient numbers to take over.
In 1942, PC-458 critically damaged U-153; in 1943, PC-565 sank U-521, capturing her skipper. Also in 1943, U-375 was sunk by PC-624. In 1944, PC-619 assisted in destroying the U-986 in the mid-Atlantic while en route to England.
Though only a few German U-boats were actually sunk by PCs, their presence, and the threat of depth charge attacks, was a deterrent to many U-boat commanders.
In the Aleutians, in a classic one-on-one encounter, PC-487 depth-charged then rammed and sank the Japanese supply submarine I-9. In the Pacific, PC-1135 sank the I-32 and SC-669 attacked and sank the Japanese sub RO-107.
With the submarine threat on the wane, the PCs and SCs took on more hazardous duties. With their shallow draft and high maneuverability, these ships proved to be exceptionally adept as beach control craft (PCCs and SCCs), controlling and guiding landing craft in every amphibious landing from North Africa to Normandy in the Atlantic theater, and Guadalcanal to Okinawa in the Pacific.
Operating close ashore and at slow speeds made them extremely vulnerable to attack. SCC-694 and SCC-696 were sunk by German dive bombers off Sicily; PCC-496 struck a mine off Sicily; PCC-558 was torpedoed in the Mediterranean; and PCC-1261 claims the dubious distinction of being sunk by a mine on D-Day, 58 minutes before H-Hour. PC-564 also sustained major damage in an engagement with German E-boats in the English channel off Normandy.
In the Pacific, SCC-700, SCC-1326 and PCC-1119 fell victim to Japanese shore batteries. A Japanese kamikaze severely damaged SCC-699 off New Guinea. At Leyte, PC-1224 was badly damaged by a Japanese bomber, and PC-1129 was sunk by a suicide boat off Luzon. SC-744 was sunk by a kamikaze in Leyte Gulf. At Okinawa, two kamikazes crashed into PCC-1603. Many more PCCs and SCCs suffered minor damage and casualties when they came within the range of enemy shore batteries.
Once aware of their effectiveness as beach control craft, the Japanese assigned entire squadrons of suicide boats to destroy or disrupt PCC and SCC activity during landing operations.
Operation Olympic, the invasion of the Japanese home island of Kyushu, was the next big invasion, planned for execution in March 1946. The PCCs and SCCs had received their assignments and were preparing for the invasion when the war ended in August 1945.
During the war, PCs and SCs underwent one major conversion. Stripped of their antisubmarine warfare equipment, the ships were rearmed and reclassified as patrol gunboat, motor, or PGM, designed to operate with patrol torpedo squadrons as Japanese "barge-busters." However, the war ended before the PGM could be fully used.
In late 1943, the first 303-foot, Tacoma class patrol frigate, or PF, joined the fleet. Manned by Coast Guard personnel, the PFs replaced many PCs as convoy escorts.
The years 1944 and 1945 saw the introduction of the slightly larger 180-foot patrol craft escort, or PCE, and the 136-foot, wood-hull patrol craft sweeper, or PCS. Both the PCE and PCS saw action in the Pacific.
Following the end of the war, most of the patrol vessel fleet was either transferred or sold to Allied countries, mothballed or sold for scrap. By late 1970 all patrol vessels had been stricken from the Naval Register.
By the late 1980s patrol combatants fell into two categories: patrol combatant (PG) and guided-missile patrol combatant (hydrofoil) (PHM). The patrol combatant was developed because of increased emphasis on counterinsurgency and unconventional warfare operations. The PG is designed for good sea-keeping qualities, long endurance, a high payload, and high speed capabilities. Although the PG is not a torpedo boat, it can operate in shallow coastal waters and is capable of combating coastal shipping as well as enemy torpedo boats.
The main propulsion plant of the modern gunboat uses a combination of diesel and gas (turbine) (CODAG). This combination achieves the greatest possible fuel economy and maximum endurance time on station. Two diesel engines drive the twin propellers during maneuvering and cruising speeds, the gunboat's normal operating condition. When high speeds are needed, the diesels are declutched and the gas turbine is clutched to the propeller shafts for speeds over 40 knots.
The modern PG is constructed of aluminum and fiberglass, is 165 feet long, has a beam of 24 feet, and displaces 225 to 245 tons. Its armament consists of one 3"/50- caliber gun, one 40-mm gun, and four 50-caliber twin machine guns. The guided- missile patrol combatant (hydrofoil) ships (PHM) USS Pegasus could operate in all weather conditions and can move in heavy seas with a stability that is usually found only in much larger ships.
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