SR.N6

During the late 1950s and early 1960s, British inventor Christopher Cockerell had, in cooperation with British aerospace manufacturer Saunders-Roe, developed a pioneering new form of transportation, embodied the form of the experimental SR.N1 vehicle, which became widely known as the hovercraft.[1] By late 1964, Saunders-Roe had commenced design work on multiple hovercraft designs; in addition to the relatively huge SR.N4 and studies into a prospective 2,000 ton freighter, there was also interest in developing its existing smaller hovercraft range.[2]

In particular, the company had observed there to be customer demand for a model of the SR.N5 that would be capable of carrying a much greater payload; there was a view that the existing craft was uneconomic for what payload it could carry and that an expanded, or 'stretched', model would be able to rectify this. According to Saunders-Roe's own projections, an increase of the craft's payload by 110 per cent would only reduce performance by 10 per cent as the increased payload was in part offset by the expanded cushion area, which meant that cushion pressure would not need to be substantially increased instead.[2]

The first craft to be lengthened in this manner, in effect becoming the first SR.N6, was the ninth SR.N5 to have been produced.[2] Following three months of work to adapt the craft to the new configuration, this first prototype was launched for the first time on 9 March 1965. Portions of the SR.N6's development were performed in conjunction with Hovertravel, a newly formed operating company located near Saunders-Roe's East Cowes facility.[3] In June 1965, following an initial series of trials, the SR.N6 prototype was delivered to operated by Scandinavian Hovercraft Promotions of Oslo, Norway under the name 'Scanhover'; it was followed by a second craft later that same month.[2]

The SR.N6 had been designed in such a fashion that it could be extended from its initial 36 seat capacity to 58 without having to perform a major redesign or incurring high building costs.[4] Work on the stretched SR.N6 was headed by Ray Wheeler, the chief designer of the British Hovercraft Corporation (BHC) - which Saunders-Roe had by then merged into. Many components and systems remained unchanged, including the relatively expensive Bristol Gnome turboshaft engine.[5] Perhaps the most substantial change on the stretched craft, beyond the increased length, was the adoption of a twin-propeller configuration, which was done in order to reduce tip speed and thus noise.[6] Hovertravel produced its first stretched SR.N6, achieved with engineering support from the BHC, by converting an existing damaged SR.N6 and two SR.N5s.[5]

SR.N6-024 at Westgate Beach, Kent 1967

Norwegian operator Scanhover served as the SR.N6's launch customer.[2] In June 1965, the first SR.N6 entered commercial service and was quickly joined by another craft. They operated on a 120-mile route, with six stopping points, in the Ålesund area. These craft were later operated between Aarhus and Kalundborg in Denmark and, during February and March 1966, also successfully underwent cold weather trials in Sweden, in the Gulf of Bothnia. The introduction of regular hovercraft services in the form of the SR.N6 attracted worldwide interest.[16]

On 24 July 1965, British operator Hovertravel took delivery of its first SR.N6, placing it into service in the Solent area on a route between the Ryde Transport Interchange on the Isle of Wight and Southsea.[17] This route was particularly well suited to hovercraft, as the tidal conditions of the surrounding coastline made berthing ships difficult, as well as a high volume of traffic; by 2012, Hovertravel had become the oldest hovercraft operator in the Western world, continuing to operate the same route.[18]

British Rail, using the operating name of Seaspeed, started a hovercraft service using the SR.N6 across the Solent between Southampton and Cowes on the Isle of Wight in 1965. This was later taken over by Hovertravel. The service ended in 1980 because of rising costs and increased competition.[19]

In 1966, operator P & A Campbell, in conjunction with Townsend Ferries, purchased SR.N6-024 to conduct a Townsend Car Ferries service, initially performing cross-Channel services between Dover and Calais. This service did not prove popular and was terminated after roughly two months.[20] During 1966 and 1967, Campbell toured various holiday resorts across Great Britain, offering pleasure rides on the craft. SR.N6-024 was subsequently sold to Hovertravel, which soon deployed it on board the Cunard ocean liner RMS Sylvania in order to perform practical demonstrations in the Mediterranean to officials of various nations as well as some trips for passengers on board.[21]

An SR.N6 landing at Ryde, Isle of Wight, 1980

In 1967, Hoverwork, a subsidiary of Hovertravel, operated a pair of SR.N6s at Expo 67, a World's fair held in Montreal, Canada, to provide passenger services between the exhibition site and Montreal itself.[22] In 1968, a single Hoverwork SR.N6 traversed a 2,400 km route of inhospitable jungle terrain within central South America, between Manaus, Brazil and Port of Spain, Trinidad, for a National Geographic scientific expedition.[23] Between Hoverwork and Hovertravel, a fleet of up to nine SR.N6s was employed on both scheduled and chartered operations around the world.[24]

Prior to its introduction of the far-larger SR.N4, British Rail's hovercraft operating division, named Seaspeed, decided to adopt a pair of SR.N6s for route proving and information gathering purposes.[25] In October 1966, Charles Brindle and several engineers surveyed several potential sites on both the British and French sides of the English Channel, using an SR.N6 to determine their suitability for the future SR.N4 service.[26][27] In late 1971, the company stretched its SR.N6 to the larger Mk 1S standard and fitted more powerful Gnome engines to account for the increased payload.[28] However, in the long term, it was determined by Seaspeed that the SR.N6 could not be profitable on the Cowes-Southampton route to which it had tasked the type.[29]

During the late 1960s, Hoverlloyd also launched a cross-Channel service using a pair of SR.N6s, running four return trips per day.[30] Like Seaspeed, Hoverlloyd used its SR.N6 fleet to gain experience prior to its own acquisition of the larger SR.N4.[31]

In 1998, the Canadian Coast Guard decommissioned its last SR.N6 that was in active service, commissioned as CCGH 045.

Military variants have seen service with the Italian Navy, Egyptian Navy, Iraqi Navy (Mk 6C), Iranian Navy and the Saudi Arabian Frontier Force.

The Iraqi Navy operated its fleet of six SR.N6s as patrol vehicles along Iraq's contested border with Iran, and were used during the Iran–Iraq War.[32]

The British Royal Marines operated SR.N6 XV589 in the Falkland Islands in the late 1960s and early 1970s to evaluate them for use in remote regions. A. Cecil Hampshire writes that Naval Party 8902 was established with a strength of 10 to use an SR.N6 in June 1967. The British Army under the Royal Corps of Transport had 200 Hovercraft Trials Squadron at lee On Solent and Browndown formed in 1966 and disbanded in 1974.

The North Korean Kongbang-class hovercraft is derived from the SR.N6. Currently the North Korean Navy fields 130 such hovercraft.[33]