The steel Porpoise class submarine Grampus was lauched from the Birkenhead yard of Cammell Laird Ltd (Yard No 1238) on 30th May 1957. She measured 290.0′ x 26.6′ x 18.0′ and her tonnage was 2080 displacement tons on surface 2450 displacement tons submerged. She was powered by 2 × Admiralty Standard range diesel generators delivering 1,650 horse power for underwater propulsion and 2 × English Electric main motors delivering 12,000 horse power to twin shafts. She was armed with 8 × 21 in torpedo tubes, 6 bow, 2 stern and carried 30 × Mk8 or Mk23 torpedoes ( later the Mark 24 Tigerfish torpedoes).
Construction of the Porpoise class submarine Grampus began when her keel in was laid in Cammell Laird’s Birkenhead yard in 1955. Finally launched in 1957 she began a lengthy fitting out process before her successful sea trials in 1958. Built to the highest modern standards her powerful diesel engines gave her a top underwater speed of 17 knots and an impressive range of 9000 miles. She was therefore capable of long secure patrols avoiding the prying eyes of her Russian adversaries. The Porpoise Class submarines were exceptionally quiet. In fact it was claimed they were 97% quieter than the preceding submarine class and even quieter when compared to her Russian equivalents. Clearly a huge advantage for a submarine. She was finally commissioned on 19th December 1958 to begin her Royal Navy career carrying a compliment of 71 officers and men.
She began a successfully but relatively uneventful career mainly involved in acoustic intelligence gathering tracking down and identifying Russian patrol submarines in the North Atlantic. In the early months of 1963 she spent three weeks under the polar ice cap returning to Gosport on 1st April to repair some superficial damage caused by collisions with the ice. In another incident, on 11th January 1968, the French trawler Fomalhaut caught Grampus in her nets in the English Channel. Grampus surfaced and both crews spent over three hours disentangling the nets.
In 1968 she was part of the First Submarine Squadron based at HMS Dolphin, Gosport and during that year she participated in Navy Days at Portsmouth and took part in Exercise Eden Apple, a large NATO deployment in the Mediterranean. In 1972, along with the other 7 submarines in her class, her weaponry was updated with Tigerfish Mark 24 torpedoes, the deadliest torpedoes in the Navy’s armoury, although thankfully they were never fired in anger.
As her career drew to an end she was assigned as a training ship between 1976 and 1979 before finally being decommissioned, stripped of her fittings and finally sent to the Ardnagowan submarine exercise are in Long Fyne to be scuttled as a sonar target. However, on her final trip on 18 September 1980, something went wrong and she sank short of her ultimate destination, a few miles north of Barmore Island. Reason for the accident is not known. The wreck of the Grampus lies in position 55° 56.853’N, 05° 23.666 W in 130 metres.