Shed Number 78 The Boat Store Building Number 78

The Boat Store, also known as Shed Number 78, is a disused boat store and warehouse built between 1856 and 1860 within the Sheerness Dockyard for the Admiralty Works Department. The design was by Col GT Green RE and William Scamp, with ironwork by Henry Grissell's Regents Canal Iron Works. It is constructed of wrought iron with corrugated iron cladding and roofing.

The building is a four-storey, 14x9-bay range with a regular arrangement of columns and floor beams. The sides have corrugated iron panels originally clad in timber, beneath full-width windows, originally with sliding sashes, now containing five casements of six panes each; the ground floor features brick infill beneath the windows, dating to 1946. A central three-bay gable is present on the west front, above ground-floor sliding doors, and a hoist bay is visible on the north side, accessing the first floor of the ninth bay from the front. The rear elevation is blank.

The interior features a frame of cast-iron H-section columns and I-section joists, with rivetted wrought-iron longitudinal beams supporting cantilever brackets for three intermediate timber joists per bay. The space is divided into three sections: a central aisle of three bays, and storage bays on either side, also three bays wide. A heavy rivetted beam spans the central aisle, one bay from the entrance, designed for hoisting. Three travelling platforms run on rails at each floor, facilitating boat transport along the building’s length and between floors. An office area, divided by glazed panels, is situated in the southeast corner of the third floor, with access provided by a timber winder stair leading to an octagonal cupola above the roof. The cupola's structure includes trusses with cruciform struts and wrought-iron tension members.

Boat stores were constructed in royal dockyards to accommodate the large number of small boats used by the navy. This store is notable for its size, efficient storage and handling methods, and its innovative structural system. The all-metal frame's rigidity, achieved through portal bracing, foreshadowed techniques later adopted in Chicago skyscrapers and became universal in modern steel-framed construction. Preceding structures can be found in earlier royal dockyard slip covers, such as those at Chatham, culminating in Green’s own No.7 slip cover. The Boat Store distinguished itself by relying entirely on the rigidity of its joints for stability. It holds international significance in the development of modern architecture. The building forms part of a group including the Boat basin and Buildings Numbers 84 and 86.