The Martin P5M Marlin (P-5 Marlin after 1962), built by the Glenn L. Martin Company of Middle River, Maryland, was a twin piston-engined flying boat that entered service in 1951, and served into the late 1960s with the United States Navy performing naval patrols. It also served with the United States Coast Guard and the French Navy. 285 were produced. Built as a successor to the PBM Mariner, it had better engines, an improved hull, and a single vertical fin tail. The XP5M Marlin prototypes were based on the last PBM-5 Mariners, the company designation being Model 237. The type was heavily improved, again leading to the P5M-2 (Model 237B), which was redesignated SP-5B. A number of P5M-1 models were also used for training, designated TP-5A (after 1962). The Marlin was designed as a gull-winged aircraft to place the engines and propellers high above the spray. Power was provided by two Wright R-3350 radial engines. The rear hull did not lift sharply from the water at the tail, instead rising up steadily, a Martin innovation; this gave the aircraft a longer base of flotation and reduced "porpoising" over waves. The prototype had nose and tail turrets with twin 20 mm (0.79 in) cannon in each, as well as a dorsal turret with two 0.5 in (12.7 mm) M2 Browning machine guns. The cockpit area was the same as the Mariner's. It first flew on 30 May 1948. For more details of the design, operational history and 15 variants, click here.