USS Guavina (AGSS-362), refueling a P5M-1 Marlin flying boat off Norfolk, Virginia (USA), in 1955. Prior to World War II several submarines were fitted to refuel seaplanes. During the war, Germany and Japan used this technique with some success. After the war this technique was experimented with within the US Navy. It was planned to use submarines to refuel the new jet powered P6M Seamaster flying boats. As part of this program Guavina was converted to carry 160,000 gallons for aviation fuel. To do this blisters were added to her sides and two stern torpedo tubes were removed. When the P6M project was canceled, there was no further need for submarine tankers. This concept was never used operationally in the US Navy.