The SR.N4 was the biggest hovercraft to have been completed upon its introduction.
Its primary structure comprised a large modular buoyancy tank, the internal structure of which being divided into 24 watertight compartments.
It had an identical platform shape to the smaller SR.N5, being rectangular with a semi-circular bow and a beam-to-length ratio of 1:1.66.

The SR.N4 was powered by four Rolls-Royce Proteus turboprop engines.
The Proteus engines each drove a set of 19 ft (5.8 m) diameter steerable Dowty Rotol propellers, arranged in two pairs on pylons positioned on top of the craft's roof; upon the SR.N4's introduction to service, these were the largest propellers in the world.
Six independent electrohydraulic systems, each driven from the main gearboxes, powered the movement of the fins and pylons, while a further four units were used to actuate the variable-pitch propellers.

The control cabin of the SR.N4 resembled the flight deck of an aircraft, being relatively cramped in comparison with the bridge of a typical vessel.
It housed a crew of three, comprising a captain, first officer/flight engineer, and a second officer/navigator; the main role of the second officer was to avoid collisions, primarily using a Decca 629 radar to do so.
The flying controls appeared broadly similar to a typical aircraft, using an assortment of rudder pedals, joysticks, yokes, separate propeller pitch levels, and engine speed controls; however, their functionality often differed substantially, such as the ability for the yoke to command the pitch of all four propellers.

The SR.N4 is fitted with a 12-ton skirt which runs under the perimeter of the whole craft and employs a complex structure.
On the underside of the buoyancy tanks, a total of five 21-inch platforms (known as 'elephant feet') were positioned so that the craft could stably rest on three of them.
Fuel was contained within flexible bags located at all four corners; the craft could be trimmed by intentionally redistributing fuel between the fore and aft tanks to better match the load and prevailing weather conditions.
The stern of the craft featured a sizeable set of doors for the loading and unloading of vehicles onto the car deck as well as all four of the exhausts for the Proteus engines, another set of loading doors were present on the front as well.
The SR.N4 was the biggest hovercraft to have been completed upon its introduction. Its primary structure comprised a large modular buoyancy tank, the internal structure of which being divided into 24 watertight compartments. It had an identical platform shape to the smaller SR.N5, being rectangular with a semi-circular bow and a beam-to-length ratio of 1:1.66.
The SR.N4 was powered by four Rolls-Royce Proteus turboprop engines. The Proteus engines each drove a set of 19 ft (5.8 m) diameter steerable Dowty Rotol propellers, arranged in two pairs on pylons positioned on top of the craft's roof; upon the SR.N4's introduction to service, these were the largest propellers in the world. Six independent electrohydraulic systems, each driven from the main gearboxes, powered the movement of the fins and pylons, while a further four units were used to actuate the variable-pitch propellers.
The control cabin of the SR.N4 resembled the flight deck of an aircraft, being relatively cramped in comparison with the bridge of a typical vessel. It housed a crew of three, comprising a captain, first officer/flight engineer, and a second officer/navigator; the main role of the second officer was to avoid collisions, primarily using a Decca 629 radar to do so. The flying controls appeared broadly similar to a typical aircraft, using an assortment of rudder pedals, joysticks, yokes, separate propeller pitch levels, and engine speed controls; however, their functionality often differed substantially, such as the ability for the yoke to command the pitch of all four propellers.
The SR.N4 is fitted with a 12-ton skirt which runs under the perimeter of the whole craft and employs a complex structure. On the underside of the buoyancy tanks, a total of five 21-inch platforms (known as 'elephant feet') were positioned so that the craft could stably rest on three of them. Fuel was contained within flexible bags located at all four corners; the craft could be trimmed by intentionally redistributing fuel between the fore and aft tanks to better match the load and prevailing weather conditions. The stern of the craft featured a sizeable set of doors for the loading and unloading of vehicles onto the car deck as well as all four of the exhausts for the Proteus engines, another set of loading doors were present on the front as well.
SR.N4