The 30-mm Goalkeeper CIWS naval air-defences system is an autonomous radar-directed short-range weapon designed for fully automatic defences against high-speed missile and aircraft, Built as a joint venture by the American company General Electric and the Dutch company Hollandse Signaalapparaten BV, the Goalkeeper has all its elements integrated on a single mount like the Phalanx system. The Goalkeeper consists of an I-band track-while-scan search-and acquisition surveillance radar, a dual frequency LK-band tracking radar, fire-control electronics and a cannon with high rate of fire, namely the 30- . mm seven-barrel GAU-8!A Sea Vulcan version of the aircraft Gatling gun. System operation is completely automatic from target detection, through target destruction and termination of the engagement, to detection of the next target. Missiles flying as low as 5 m (16.4 ft) have been successfully destroyed, and the tracking radar can also be used against high-elevation diving targets. For multiple attacks there is an automatic kill-assessment subsystem to assign target priorities. The AP discarding-sabot round has, instead of the original depleted-uranium penetrator, one made of a high-density tungsten alloy, For softer targets an HE incendiary round is employed, A total of 1,190 rounds is carried in a link less feed drum-storage system. To replenish this storage/feed arrangement a bulk loading system is used, but in an emergency manual reloading can be performed. The Goalkeeper system has been chosen by the Royal Netherlands navy for its 'Kortenaer', 'Jacob van Heemskerck' and future 'M' class frigates. The Royal Navy has also ordered a number for fitting to its four "Type 22 Batch 3' class frigates and the new 'Type 23' or 'Duke' class medium sized frigates.

Specification Goalkeeper      Caliber: 30 mm

Number of barrels: seven Elevation: -25° to +85°

Muzzle velocity: 1021 m (3,350 ft) per second

Effective range; 3000 m (3, 280 yards) Rate of fire: 4, 200 rounds per minute Weight: (with ammunition) 6730 kg (14,837 lb)

Number of rounds carried on mount: 1,190