Whitby - class frigate The Type 12 or " Whitby " - class frigates were a six - ship class of anti - submarine frigates of the Royal Navy that entered service late in the 1950s . They were designed as first - rate ocean - going convoy escorts in light of experience gained during World War II . At this time the Royal Navy were designing single - role escorts , and the " Whitby " s were designed as fast convoy escorts capable of tackling high - speed submarines . However , this made the " Whitby " s more expensive and sophisticated to produce in large numbers in the event of a major war , and so the Type 14 " utility " or " second - rate " anti - submarine frigate was developed to complement the Type 12 . Although themselves rapidly outdated , the Type 12 proved to be an excellent basis for a series of frigate designs used by the British and Commonwealth navies for the next 20 years . Design . Critical to the design of the Type 12 was the requirement to be able to steam for long periods of time in heavy seas , economically and at high speed . For this reason a novel hull form was devised , which despite appearance , was totally unrelated to that of the earlier Type 41 / Type 61 design . The hull showed the fine lines more typical of a destroyer , but had a raised forecastle with considerable flare . The fo ' c ' sle deck was level to maintain maximum freeboard aft of the stem where it is most likely that waves will break across the deck . These two features meant that the hull not only cut through the water , but that spray was thrown upwards and outwards , away from the bridge and gun turret . This was especially important in high latitudes where war experience had shown that spray could cause rapid and undesirable ice build - up on the forecastle . The deck edges and hull also met at a curve rather than an angle , the anchors were recessed , and protrusions were kept to a minimum to limit the potential sources of ice build - up and spray generation . The Mark 6 gunhouse was large and heavy , so had to be carried low to maintain stability and give a good view over it from the bridge . The forecastle therefore had a very distinctive kink , allowing the position of the guns to be lowered . This had the added benefit of moving the bridge aft , where there was considerably less motion , improving the lot of the watchkeeper . The hull form , coupled with a twin - shaft double - reduction geared steam turbine plant ( the Y - 100 ) that operated at high temperature and pressure ( for efficiency ) and low revolutions , with new five - bladed low - cavitation propellers ( for efficiency and quietness ) lent themselves to the perfect hull for a high - speed , all - weather anti - submarine vessel . Experience with the Type 15 frigate program , rebuilding wartime destroyers into fast anti - submarine frigates had led to the adoption of a bridge design characteristic of Royal Navy escorts up to the " Leander " class of 1969 . The covered bridge , where the ship was conned , was located above the operations room where the ship was fought , and there was a small pilot ' s position located to the front of the bridge , giving the indicative " T " shape when viewed from above . " Whitby " was unique in that her bridge face was vertical , her sisters having the windows mounted at an angle to the face , to cut down on internal reflections inside the bridge in low - light . There was also an open navigation bridge located above and behind the enclosed one . The original funnel was a straight , cylindrical affair that was designed to resist a nuclear blast , but this was prone to down - draughting and did not clear the hot exhaust gasses particularly well . It was replaced by a heightened , raked , streamlined version with a characteristic domed top . This was incorporated in later build vessels , and in all of the subsequent " Rothesay " class . Only " Scarborough " retained the stubby vertical funnel throughout her career . Armament . The armament was based around two Limbo Mark 10 anti - submarine mortars . This allowed a three - bomb salvo to be placed both above and below the target , creating a convergent pressure wave more likely to assure a kill . The Limbos were mounted in a well on the quarterdeck , with a 360° arc of fire . Again , wartime experience had shown that the quarterdeck , perhaps not an obvious location for an ahead throwing weapon , was indeed the best location for such weapons where they were out of the spray towards the front of the vessel . The Limbo mortars were controlled by three sonars , the Type 174 search set , Type 162 target classification set and the Type 170 ' pencil beam ' targeting set . The lattice foremast carried the radar Type 293Q target indication set and the Type 974 navigation set , and a Type 277Q height finder was carried on a stump mast between the bridge and the mainmast . These sets were all derived from units of second world war vintage . Carrying the Limbos aft allowed the forecastle to be left clear for the twin 4 . 5in Mark 6 gun for anti - surface and limited anti - aircraft fire , controlled by a Mark 6M director with radar Type 285 mounted behind the bridge . Further anti - submarine capability was to be afforded by twelve 21 inch Mark 20E " Bidder " anti - submarine homing torpedo es , carried in fixed tubes ; Four pairs were fixed firing forward on either beam , with a trainable pair behind these on each side . Ultimately the E version of the Mark 20 torpedo was a failure as it was not nearly fast enough to catch its intended target , and the tubes were removed ( where they were fitted at all ) and the torpedoes never deployed . Self - defence against aircraft was provided by the elaborate STAAG weapon , a complex and ultimately failed exercise in engineering . The STAAG , or " Stabilised Tachymetric Anti - Aircraft Gun " , consisted of a two Bofors 40 mm L / 60 guns , the radar Type 262 fire control set and a tachymetric computer ( predictor ) . All this was carried on a common , stabilised , powered - operated gun mounting . Intended to function much as the modern CIWS does , this weapon was ahead of the limits of technology at the time and was overweight , overly complex and its sensitive valve electronics were a maintenance nightmare . Ultimately STAAG would be replaced by a simple and ubiquitous Bofors 40 mm gun on the single Mark 7 mounting . Service . The " Whitbys " served up until the 1970s , when increasing age and defence economies led to their gradual withdrawal or re - assignment . In 1966 , " Blackpool " was loaned to the Royal New Zealand Navy , while they waited for the delivery of , a " Leander " - class frigate . It would remain in New Zealand service until 1971 when it returned to the Royal Navy , and decommissioned that same year . All other ships , except " Eastbourne " and , were decommissioned in the 1970s . The latter two ships were decommissioned in 1984 and 1985 respectively . " Scarborough " and " Tenby " were intended to have been sold to Pakistan , but the country could not afford the refits required for the two ships , and thus the sale was aborted . " Blackpool " was decommissioned for use as a target vessel in the Firth of Forth , " Eastbourne " became an engine room training ship alongside at at Rosyth and " Torquay " was modified and fitted with CAAIS ( " Computer Assisted Action Information System " ) for use as a trials and training ship . Construction programme . Models . In 1959 Triang Minic Ships produced a series of 1 : 1200 ( one inch to 100 feet ) metal models of Type 12 frigates , carrying the names " Whitby , Tenby , Torquay " and " Blackpool " . These toys were mass - produced in large numbers between 1959 and 1965 , and did much to raise awareness of these post - war ships for the younger generation . At the same time the Frog ( models ) company produced an accurate plastic model kit of HMS " Blackpool " to a scale of 1 : 500 . The moulds for this were sold to Russia in 1976 , and it has been re - issued under the " Novo " trademark on several occasions .