to a standard International Union of Railways (UIC) locomotive. The UIC approved the PA6 in 1971 and the first engines were produced in 1972. In 1975, the high speed PA6 BTC for naval ships in 1975 was introduced. In 1981, the PA6 CL long-stroke engine with reduced fuel consumption was released. In 1988, the PA6 STC, which used sequential turbo-charging for naval ships, was introduced. In 1995, SEMT launched the final engines in the series, the PA6 B and high-speed PA6 B STC in 1995, providing increases in power and overall performance. The PA5 was launched in 1981 to meet an initial market demand from the Japanese fishing fleet. A dual-fuel version would later be developed (diesel fuel and gas) for electricity generating stations. Major installations French Navy surface ships SEMT has provided PA and PC engines for many French naval vessels the Georges Leygues, La Fayette, Floréal, Cassard and Horizon frigates; the A69 avisos P400 patrol boats; the Jules Verne repair ship; the Durance class of oil tankers (one of which was built in Australia as HMAS Success) the Foudre and Ouragan Landing Platform Docks. Other naval surface ships SEMT provided engines to the Saudi F 3000 S frigates (Sawari II program) and the Sigma class frigates for the Moroccan Navy (2 x 20 PA6B STC). Through Fairbanks Morse Engines, SEMT engines have been purchased by the US Navy, The 16-cylinder PC2.5 STC engine were used by the USN for the San Antonio-class LPD 17 troop transporters, which are each equipped with four engines The PA and PC engines have been used by Australia, China, Canada, India, the United Kingdom, South Korea, Indonesia and Russia, along with the Japan Coast Guard. Submarines The PA4 engine was adapted for use by submarines, leading to the SM versions of the PA4 185 and 200. These were equipped with Hispano-Suiza compressors – given the particular constraints in terms of air aspiration and exhaust gases within a submarine. The compressor also minimized the pressure variations created by the sea swell, increasing the reliability of the engine and therefore the safety of the entire propulsion system. Merchant ships Large ships (cruise liners, cargo ships and container ships) traditionally use medium-speed PC engines, Smaller vessels use high-speed PA engines Japanese licensee Niigata identified strong demand among the country's fishing fleet – requiring an engine that would fit the trawlers exactly. The result was the design