HMS ''Excalibur'' was an , the sister ship of , the only two

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

s powered by

high-test peroxide High-test peroxide (HTP) is a highly concentrated (85 to 98%) solution of hydrogen peroxide, with the remainder consisting predominantly of water. In contact with a catalyst, it decomposes into a high-temperature mixture of steam and oxygen, with n ...

(HTP) which were constructed for the

Royal Navy The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...

. She is the only commissioned ship in the Royal Navy to be named as such, in honour of the

sword A sword is an edged and bladed weapons, edged, bladed weapon intended for manual cutting or thrusting. Its blade, longer than a knife or dagger, is attached to a hilt and can be straight or curved. A thrusting sword tends to have a straighter ...

Arthurian According to legends, King Arthur (; ; ; ) was a king of Britain. He is a folk hero and a central figure in the medieval literary tradition known as the Matter of Britain. In Welsh sources, Arthur is portrayed as a leader of the post-Ro ...

legend A legend is a genre of folklore that consists of a narrative featuring human actions, believed or perceived to have taken place in human history. Narratives in this genre may demonstrate human values, and possess certain qualities that give the ...

. In 2025, the Royal Navy christened a non-commissioned uncrewed submarine of the same name into service for the purpose of testing unmanned underwater systems.

Operation

Both ''Excalibur'' and ''Explorer'' were assigned to the 3rd Submarine Squadron. However, due to their experimental nature, they tended to operate independently, accompanied by their depot ship HMS ''Kingfisher'' and the fuel carrier RFA ''Spabeck''. They later acted as high-speed underwater targets for the Royal Navy's prototype nuclear-powered submarine .

Periscope

The submarine's periscope survives. It was installed in the starter's hut at the ''Golf House Club'', the golf club at

Elie and Earlsferry Elie and Earlsferry is a coastal town and former royal burgh in Fife, and parish, Scotland, situated within the East Neuk beside Chapel Ness on the north coast of the Firth of Forth, eight miles east of Leven. The burgh comprised the linked vill ...

, Scotland; players and visitors may use it to view the golf course.

References

Bibliography

* * * {{DEFAULTSORT:Excalibur Explorer-class submarines Ships built in Barrow-in-Furness 1955 ships Cold War submarines of the United Kingdom