SR.N4

Mark III SR.N4 arriving in Dover on its last commercial flight October 2000
Class overview
Name	SR.N4 Mountbatten class
Builders	British Hovercraft Corporation
Operators	Hoverlloyd Seaspeed Hoverspeed
In service	1968–2000
Completed	6
Scrapped	5
Preserved	1
General characteristics (Mark III)
Type	Hovercraft
Tonnage	320 t
Length	56.38 m (185 ft 0 in)
Beam	23.77 m (78 ft 0 in)
Height	11.48 m (37 ft 8 in) on landing pads
Installed power	3,800 shp (2,800 kW)
Propulsion	4 x Rolls-Royce Marine Proteus gas turbines for lift and propulsion, each driving a single four-bladed variable-pitch propeller
Speed	70 knots (130 km/h)
Capacity	up to 60 cars and 418 passengers

The SR.N4 (Saunders-Roe Nautical 4)^[1] hovercraft (also known as the Mountbatten class hovercraft) was a combined passenger and vehicle-carrying class of hovercraft.^[2] The type has the distinction of being the largest civil hovercraft to have ever been put into service.

Work on the SR.N4 was initiated in 1965 by Saunders-Roe. By the time that the vehicle's first trials took place in early 1968, Saunders-Roe had merged with Vickers' hovercraft division to form the British Hovercraft Corporation, who continued development. Power was provided by four Rolls-Royce Proteus marine turboshaft engines each driving its own lift fan and pylon-mounted steerable propulsion propeller. The SR.N4 was the largest hovercraft then built, designed to carry 254 passengers in two cabins besides a four-lane automobile bay which held up to 30 cars. Cars were driven from a bow ramp just forward of the wheelhouse. The first design was 40 metres (131 ft) long, weighed 190 long tons (193 t), was capable of 83 knots (154 km/h) and could cruise at over 60 knots (111 km/h).

The SR.N4s operated regular services across the English Channel between 1968 and 2000. In response to operator demands, stretched versions of the SR.N4 were developed, culminating in the Mk.III variant, which had almost double the capacity for carrying both cars and passengers as the Mk.I. While interest was expressed in military applications for the type, no vehicles were ultimately used for such purposes. Following the fleet's withdrawal from cross-channel services, a single remaining Mk.III example, GH-2007 Princess Anne, remains on static display at the Hovercraft Museum at Lee-on-Solent as of August 2021.