Tigerfish ( torpedo ) The Mk 24 Tigerfish torpedo was a heavyweight acoustic homing torpedo used by the Royal Navy ( RN ) for several years . The early Mod0 and Mod1 variants were unreliable and unsuccessful , but were issued to the RN even though they failed Fleet Weapon Acceptance . Reliability was significantly improved in the Mod2 variant as a result of the Consolidation Programme which addressed the complete weapon system i . e . the on - board fire control system ( TCSS10 and DCB ) and the Mk24 torpedo . The Consolidation Programme was initiated following the torpedo ' s reliability failures during the Falklands War . It was headed by Marconi Underwater Systems Limited as Prime Contractor with Ferranti Computer Systems Ltd and Gresham Lion as major sub - contractors . Tigerfish was eventually replaced in - service by the much more capable Spearfish torpedo . It was fitted with both active and passive sonar and could be remotely controlled through a thin wire which connected it to the launching submarine . Wire guidance permits a torpedo to be launched on - first - warning , i . e . when a target is first detected at long range . This permits the torpedo the time needed to close the range while target course and speed is being updated by the submarine ' s superior sensors and transmitted ' down - the - wire ' . The torpedo can also be re - assigned to another target or recalled . Typically , wire - guided torpedoes initially run at low speed ( in order to maximize their range and to minimize their self - generated noise ) while they close the range ( the approach speed ) and speed up during the attack phase ( the attack speed ) . Design and development . The initial concept developed in the mid - 1950s was for a very fast ( 55 knot / 100 km / h ) , deep - diving torpedo driven by an internal combustion engine , carrying high pressure oxygen as oxidant , guided by a wire system developed from the Mackle wire - guidance study dated 1952 using data transmitted from the firing submarine sonar s and using an autonomous active / passive sonar developed from the abandoned 1950s UK PENTANE torpedo project . The weapon was known as Project ONGAR because Ongar railway station was , until 1994 , the last on the Central Line of the London Underground system . The engineers developing this weapon were confident that it would be so advanced that it would be " . . . the end of the line for torpedo development " . The programme ran into serious problems in the late 1950s because the technology required was too advanced to meet an in - service target date of 1969 . In addition , the closure of the Torpedo Experimental Establishment , Greenock , Scotland in 1959 and the transfer of its staff to Portland in Dorset disrupted the pace of development . In the early 1960s a series of wide - ranging reviews ( one report was titled " Whither ONGAR ? " - the pun being intentional ) led to a greatly reduced performance specification which was realistically expected to achieve an in - service date of 1969 . The propulsion system was changed from an internal combustion engine to an electric motor with a silver zinc battery as the power source . This reduced the planned speed of the weapon from 55 knots to 24 knots ( 100 km / h to 44 km / h ) with a short final - attack - phase capability at 35 knots ( 64 km / h ) . The homing system was simplified by the exclusion of the anti - surface ship capability in the Mod 0 weapon . Only the wire - guidance system was retained relatively unchanged . This was similar to the system used on the earlier Mk 23 torpedo . The original requirement for a crush depth of 1 , 000 ft ( 300 m ) was overtaken by rapid advances in SSN deep - diving performance and the requirement was progressively increased to 1 , 600 ft ( 490 m ) and then 2 , 000 ft ( 600 m ) . Tigerfish never met these requirements and the best that could be achieved was 1 , 150 ft ( 350 m ) and later 1 , 450 ft ( 440 m ) ; the structure was incapable of further crush - depth development . In - service performance . Early models suffered from poor reliability : only 40 % of the Mod 0 ASW model performed as designed . The torpedo depended in large part on the remote - control system , but the weapon tended to dip during launch , severing the control wire . The Mod 0 failed its initial fleet acceptance trials in 1979 but was nevertheless issued to the fleet in 1980 . The Mod 1 DP ( dual purpose ) anti - submarine and anti - ship model also experienced problems , though a redesigned version ( Mod 2 ) passed sea trials in 1978 and was issued the following year . When HMS " Conqueror " sank the ARA " General Belgrano " during the 1982 Falklands war she used the " point and shoot " 21 " Mark VIII torpedoes rather than her Tigerfish . The Mark VIII had no homing system but , despite the design being over 50 years old at the time , was far more reliable and carried a greater high - explosive payload . In a test carried out by submarines returning to the UK after the war two of five Mod 1 Tigerfish fired at a target hulk failed to function at all and the remaining three failed to hit the target . A measure of the Royal Navy ' s desperation for a reliable means of dealing with fast , deep - diving , time - urgent targets at long range resulted in a project to arm Tigerfish with a nuclear warhead to offset its poor diving depth and homing performance and to increase kill probability close to 90 % . Various other measures were proposed in mid - 1969 , including purchase of U . S . weapons such as the Mark 45 ASTOR nuclear torpedo , the Mark 48 Mod - 1 torpedo or the Subroc rocket . Alternatively , at the initiative of Flag Officer Submarines ( FOSM ) , a nuclear warhead might be fitted to the unguided , shallow - running and short - ranged , but reliable Mark VIII torpedo . Flag Officer Submarines minuted that the proposal to arm the Mark VIII with the WE . 177 A warhead would , despite the torpedo ' s performance shortcomings , be " much superior to any present British submarine weapon . . . " However , the short range of the Mark VIII put the firing submarine within damage range of the nuclear warhead of its torpedo . The Marconi Consolidation Programme of the early 1980s finally produced the Mod 2 with reliability improved to 80 % , which the Royal Navy accepted as the best that could be achieved with a basic design that was incapable of further development . By 1987 all 600 Tigerfish had been modified to the Mod 2 standard . The tribulations with the Tigerfish torpedo development , from its concept in the mid - 1950s to the introduction of the unsuccessful Mod 0 variant into Royal Navy service in 1980 , were responsible for the decision to purchase cruise missiles to attack ships from Royal Navy submarines . Versions were : In 1990 Cardoen of Chile was granted a licence to manufacture Tigerfish for the Chilean , Brazilian and Venezuelan navies . The Royal Navy retired the last of the Tigerfish torpedoes from service in February 2004 .