The Porpoise-class submarine was the first new submarine class launched by the Royal Navy after World War II with first of class HMS Porpoise being launched in 1956. In the period between 1945 and 1956 the Royal Navy’s submarine assets continued to comprise of the war-era T-class albeit it in its upgraded and smoothed off version to reduce its underwater acoustic signature. Somewhat ironically although not uncommon amongst the wartime allies the Porpoise-class was inspired by German advancements made in the closing stages of the war.
The Porpoise-class was one of the most capable conventional submarines available to NATO in the late 50s and early 60s. They were perhaps the quietest submarines in NATO and were far quieter than the equivalent Soviet Navy Whiskey-class. This meant they were difficult to detect; a fact dramatically proven when during exercises HMS Rorqual managed to make it all the way to the Statue of Liberty undetected by the US Navy. Top speed was 18knots submerged although a more economical (and quieter) 14knots was the norm.
The Porpoise-class was the first submarine class in the Royal Navy not to be fitted with a deck gun since the R-class of World War I. This was because deck guns had become obsolete weapons due to the increasingly sophisticated detection methods employed by ASW forces that required all attacks to be made submerged. Additionally the removal of the gun reduced underwater drag and noise. The Porpoise-class was armed with eight 530mm torpedo tubes with four forward facing and two aft. A complement of 30 torpedoes could be carried or alternatively the tubes could fitted with mines.