It was powered by a single 300 horsepower (220 kW) Hispano-Suiza 8F V8 engine, mounted on two N struts above the hull and below the upper wing, which drove a two-bladed propeller in a pusher configuration.

[2] Italy entered the S.51 in the 1922 Schneider Trophy race along with two Macchi M.17 flying boats in competition with a British Supermarine Sea Lion II flying boat.

[5] Righted by its crew, it completed the race, piloted by Alessandro Passaleva but could only take second place, with the Sea Lion a comfortable 2 min 22 s ahead.

The course required 13 laps, a total distance of 370 km (230 mi), over which the S.51 averaged 229.57 km/h (142.65 mph).

[3][4] On 28 December 1922 the S.51, flown again by Passaleva, set a world speed record for seaplanes of 280.155 km/h (174.080 mph).