World Wide Corvettes - 500 to 2,500 tons

A corvette is a small warship, classed between a frigate and a sloop-of-war. The terms frigate and corvette, which before the introduction of heavy guns designated well-defined types, were nevertheless used quite arbitrarily. In the age of sail, the original classification into ships of the line, frigates, and corvettes called all cruisers with covered batteries frigates, and limited the term corvette to those ships which were flush-decked with no covered batteries. In the late 19th Century, ships with 'tween deck batteries were called frigates or 'decked' corvettes. Ships with open batteries were called 'flush' decked corvettes.

Before the days of the steam turbine and steel hull, a corvette was larger than a sloop, but smaller than a frigate and usually characterised by a single gun deck. Corvettes usually were flush-decked and carried fewer than 28 guns. They were widely employed in escorting convoys and attacking merchant ships during the great naval wars of the late 18th and early 19th centuries. Their tasks would include small-scale combat, 'showing the flag' of a country around the world, or supporting larger fleets of bigger ships. Capable naval platform that helped to protect the convoys, in some ways corvettes are odd vessels; bigger than an offshore patrol craft, but lacking the size of a frigate; a bridge between a navy's brown-and blue-water capabilities.

With the miniaturisation of today's electronic systems, vessels of corvette-size are able to pack in more technology than previously thought possible. The development of space-saving multi-purpose devices from video-displays to missile launchers allow more by the way of weaponry, electronics and computing equipment. Already able to fit in a variety of SSMs like the Exocet and Harpoon, these fittings extend to SAMs and torpedoes.

New lightweight and compact air detection and defence systems were rapidly developed. The Sea Sparrow ship-launched, point-defence missile has semi-automatic/automatic modes with vertical-launch options. Vertical launch systems reduce the space taken up. Fully containerised Israeli IAI Barak vertical-launch AA missile launchers are available with particular attractiveness, as they require no deck penetration for fitting. Matra has also developed the Mistral launcher, designed for use on small vessels against aircraft and helicopters within the 4 to 6km range. The ubiquitous 76mm OTO Melara also has an upgraded super rapid-fire version to cope with air threats. Close-in weapon systems (CIWS), once thought of as suitable for major surface combatants now also have versions, like the Breda Twin 30mm guns, suitable for corvettes.

The larger build of the corvette comes along with the advantages of longer range and better seakeeping. This extra range is a consideration in view of the tighter defence budgets with the recent economic downturn. The new corvette would be expected to fulfil a multi-role function that goes beyond limited strike operations.

The weapon systems associated with corvettes are a yardstick for marking the importance of these ships. The most common remains the rocket-powered MBDA Exocet, while other options include the Saab Bofors Dynamics' turbojet-powered RBS15 missile, the Boeing Harpoon, one of the most common anti-ship missiles, and the Russian equivalent of the Harpoon, the 3M24 Uran (SS-N-25 'Switchblade'). A very common ordnance is the Oto Melara 76-mm 62-calibre gun. The smallest weapon used is the BAE Systems Bofors SAK 57, a single barrel 57-mm 70-calibre gun capable of 220 rounds/min. The corvette also has potential for Anti-Submarine Warfare and many now carry launcher systems for lightweight (32 to 40-cm diameter) torpedoes. These weapons have passive sonar to detect the target while travelling at relatively low speeds in a search pattern and then an active sonar which can be used to engage it.