Watersports Hangar (Calshot Former Rnas Station Circa 250 Metres West of Castle)

The watersports hangar, formerly a flying boat hangar, is located at the former Royal Naval Air Station at Calshot, approximately 250 meters west of the castle. It was built in 1914 or possibly earlier and features a timber frame with corrugated metal cladding and a pitched, felted wooden roof. The structure has a rectangular plan with ten bays, covering an area of about 720 square meters. It includes sliding wooden doors on the west side, while the east side has a unique set of surviving wooden "roll-up" slat doors. There is a single-storey outshut to the north and a range of five lights to the south.

Inside, the hangar boasts wooden lattice-braced "bowstring" roof trusses. This hangar is a unique surviving example of its type, as later hangars from the World War I period typically had 100-foot spans, whereas this early example has an 80-foot span. It was likely constructed to accommodate the Sopwith Bat Boat, which was used at Calshot from 1913. The hangar is part of an exceptional group of aircraft hangars from 1914-1918 that demonstrate the evolution of aircraft technology during World War I. Its design is said to be associated with Barnes Wallis, although there is no definitive evidence to support this claim, as Wallis worked on airship design for Vickers Ltd before the war. The hangar is also linked to the renowned Schneider Trophy seaplane contests held at Calshot in 1929 and 1931.