A hovercraft, also known as an air-cushion vehicle or ACV, is a craft capable of travelling over land, water, mud or ice and other surfaces both at speed and when stationary. Hovercraft are hybrid vessels operated by a pilot as an aircraft rather than a captain as a marine vessel. Hovercraft use blowers to produce a large volume of air below the hull that is slightly above atmospheric pressure. The pressure difference between the higher pressure air below the hull and lower pressure ambient air above it produces lift, which causes the hull to float above the running surface. For stability reasons, the air is typically blown through slots or holes around the outside of a disk or oval shaped platform, giving most hovercraft a characteristic rounded-rectangle shape. Typically this cushion is contained within a flexible "skirt", which allows the vehicle to travel over small obstructions without damage. The first practical design for hovercraft derived from a British invention in the 1950s to 1960s. They are now used throughout the world as specialised transports in disaster relief, coastguard, military and survey applications as well as for sport or passenger service. Very large versions have been used to transport hundreds of people and vehicles across the English Channel whilst others have military applications used to transport tanks, soldiers and large equipment in hostile environments and terrain. Although now a generic term for the type of craft, the name Hovercraft itself was a trademark owned by Saunders-Roe (later British Hovercraft Corporation (BHC), then Westland), hence other manufacturers use of alternative names to describe the vehicles. The Zubr-class (Project 1232.2 class, NATO reporting name Pomornik) is a class of air-cushioned landing craft of Soviet design. This class of military hovercraft is, as of 2012, the world's largest hovercraft.[4] It is designed to sealift landing assault units (such as marines or tanks) from equipped/non-equipped vessels to non-equipped shore, as well as transport and plant mines. There are currently nine ships in active service in the world. The Zubr is used by the Russian, Ukrainian, and Greek navies.[3] The transfer of the Kefalonia (L- 180), the first of two Zubr hovercraft purchased by Greece,[5] to the Hellenic Navy marked the first time that a Russian-made ship was purchased by the navy of a NATO member.[6][7][8] High strength and buoyancy of the craft are provided by a rectangular pontoon, the main load-carrying part of the ship's hull. The superstructure built on the pontoon is divided into 3 compartments with two longitudinal bulkheads: combat material compartment in the midsection fitted with tank ramps, and outboard sections housing main and auxiliary propulsion units, troop compartments, living quarters, and NBC protection systems. To improve working conditions in the battle stations, troop compartments and living quarters are fitted with air-conditioning and heating-systems, sound/heat-insulating coatings, and structures made of vibration damping materials. The ship provides normal conditions for the crew to take meals and rest. Personnel are protected against the effects of weapons of mass destruction by airtight sealing of combat stations, crew and troop compartments, augmented with individual gas masks and protection suits. The ship is also protected from magnetic influence mines with an active system to compensate for the magnetic fields generated by the ship and transported materials. The central command post and MS-227 device compartments are strengthened with alloy armor. The Zubr landing craft has a cargo area of 400 square metres (4,300 sq ft), and a fuel capacity of 56 tons.[2] It can carry three main battle tanks (up to 150 tonnes), or ten armoured vehicles with 140 troops (up to 131 tonnes), or 8 armoured personnel carriers of total mass up to 115 tonnes, or 8 amphibious tanks or up to 500 troops (with 360 troops in the cargo compartment). At full displacement the ship is capable of negotiating up to 5-degree gradients on non-equipped shores and 1.6m-high vertical walls. The Zubr remains seaworthy in conditions up to Sea State 4. The vessel has a cruising speed of 30-40 knots. Russia Listeni/ˈrʌʃə/ or /ˈrʊʃə/ (Russian: Россия, tr. Rossiya, IPA: [rɐˈsʲijə] ( listen)), also officially known as the Russian Federation[7] (Russian: Российская Федерация, tr. Rossiyskaya Federatsiya, IPA: [rɐˈsʲijskəjə fʲɪdʲɪˈrat͡sɨjə] ( listen)), is a country in northern Eurasia.[8] It is a federal semi-presidential republic, comprising 83 federal subjects. From northwest to southeast, Russia shares land borders with Norway, Finland, Estonia, Latvia, Lithuania and Poland (both with Kaliningrad Oblast), Belarus, Ukraine, Georgia, Azerbaijan, Kazakhstan, China, Mongolia, and North Korea. It shares maritime borders with Japan by the Sea of Okhotsk and the U.S. state of Alaska across the