All Royal Navy vessels were identified by Pennant, or Pendant, numbers, which had one or two components. These two components were known as the flag superior and the flag inferior. Flags superior consisted of a letter or a number, some of which were changed before and during the war. The flags inferior had numbers. The numbers themselves were apparently picked at random. (Excluding the coastal forces, where the boat's numerical name itself was worn as the flag inferior.) Besides being used for identification during signaling, the smaller vessels also had their pennant numbers painted on their hulls.
Pennant numbers were introduced to help to abbreviate signalling and to help make signals more secure, they also served to clear up confusion between ships with similar names and as an aid in identifying ships visually, particularly where ships of the same classification were grouped in a Squadron.
During the wars, many vessels were transferred between Commonwealth and Allied Navies. Where this did occur, the vessel usually kept the same Pennant Number (even though the vessels name may well have changed). If a vessel was sunk in action, it was usual for the Pennant Number of that ship to be allocated to the next vessel to be launched.
Between the wars the submarine pennant number was the reverse of the boats (numerical) name or an identifying number followed by the class letter in the case of a named boat. I.e., numeral pennant and a flag inferior. The flags used were H or L for the H and L class, P for the O and P class, R for the R class, F for the Thames class, M for the Porpoise class, S for the S class, T for the T class, and C for the U class.
Until the Second World War, it was usual for submarines to have only a Pennant Number and no name, Winston Churchill directed that all Submarines be named. Some minor ships had no Pennant Number, whilst others had them removed from photographs due to censorship. It is believed that the pennant system was last revised in 1947. At that time K, L and U all became F.
Then in 1939 all submarines were allocated pennant numbers ending with the N (N flag inferior), the numbers remained unchanged. In May 1940, this was changed to flag N superior. Again, the numbers themselves remained unchanged
Early in the war it was decided that submarines built (or acquired) during the war would no longer be given names but only the letter P and a number. (To prevent enemy recognition of new submarines.) Then in 1942, it was once again decided that all submarines would be named.
Titanic. The name of this famous ship (or infamous, depending on the way you look at history) reverberates throughout the century since she sank in 1912. Her sinking was the instigator of many changes, developments and innovations not least the genesis of the US Coast Guard and SOLAS. Among the innovations of how to detect obstructions at sea, like an iceberg, was one conceived by a Canadian born radio engineer, Reginald Fessenden working as a consultant to the Submarine Signal Company to enhance their system of underwater bells for shore-based stations, buoys, and light ships and for sound detection on ships.
During the Cold War, nuclear submarines performed the greatest public service of all: prevention of a third world war. History shows that they succeeded; the Cold War ended peacefully, but for security reasons, only now can this story be told.
Eric Thompson is a career nuclear submarine officer who served from the first days of the Polaris missile boats until after the end of the Cold War. He joined the Navy in the last days of Empire, made his first sorties in World War II type submarines and ended up as the top engineer in charge of the navy's nuclear power plants. Along the way, he helped develop all manner of kit, from guided torpedoes to the Trident ballistic missile system. In this vivid personal account of his submarine operations, he reveals what it was like to literally have your finger on the nuclear button.
In his journey, the author leads the reader through top-secret submarine patrols, hush-hush scientific trials, underwater weapon developments, public relations battles with nuclear protesters, arm-wrestling with politicians and the changing roles of females and homosexuals in the Navy. It is essentially a human story, rich in both drama and comedy, like the Russian spy trawler that played dance music at passing submarines. There was never a dull moment.
Behind the lighter moments was a deadly serious game. This, the inside story of Britain's nuclear deterrent, reveals the secretive life of submarines and the men who served on them; they kept their watch, and by maintaining the threat of 'Mutually Assured Destruction' helped keep Britain and the world safe.
17 pages added or updated in the last 1 month
Please help to maintain this site by reporting any Errors, Broken Links, Information or Site Issues on this page using this button
If you find this site useful, please consider supporting my work with a small Donation.
Please Note: Donations made using this option go directly to the site owner and not to the Submariners Association.
Thankyou for your support.
All Royal Navy vessels were identified by Pennant, or Pendant, numbers, which had one or two components. These two components were known as the flag superior and the flag inferior. Flags superior consisted of a letter or a number, some of which were changed before and during the war. The flags inferior had numbers. The numbers themselves were apparently picked at random. (Excluding the coastal forces, where the boat's numerical name itself was worn as the flag inferior.) Besides being used for identification during signaling, the smaller vessels also had their pennant numbers painted on their hulls.
Pennant numbers were introduced to help to abbreviate signalling and to help make signals more secure, they also served to clear up confusion between ships with similar names and as an aid in identifying ships visually, particularly where ships of the same classification were grouped in a Squadron.
During the wars, many vessels were transferred between Commonwealth and Allied Navies. Where this did occur, the vessel usually kept the same Pennant Number (even though the vessels name may well have changed). If a vessel was sunk in action, it was usual for the Pennant Number of that ship to be allocated to the next vessel to be launched.
Between the wars the submarine pennant number was the reverse of the boats (numerical) name or an identifying number followed by the class letter in the case of a named boat. I.e., numeral pennant and a flag inferior. The flags used were H or L for the H and L class, P for the O and P class, R for the R class, F for the Thames class, M for the Porpoise class, S for the S class, T for the T class, and C for the U class.
Until the Second World War, it was usual for submarines to have only a Pennant Number and no name, Winston Churchill directed that all Submarines be named. Some minor ships had no Pennant Number, whilst others had them removed from photographs due to censorship. It is believed that the pennant system was last revised in 1947. At that time K, L and U all became F.
Then in 1939 all submarines were allocated pennant numbers ending with the N (N flag inferior), the numbers remained unchanged. In May 1940, this was changed to flag N superior. Again, the numbers themselves remained unchanged
Early in the war it was decided that submarines built (or acquired) during the war would no longer be given names but only the letter P and a number. (To prevent enemy recognition of new submarines.) Then in 1942, it was once again decided that all submarines would be named.
Titanic. The name of this famous ship (or infamous, depending on the way you look at history) reverberates throughout the century since she sank in 1912. Her sinking was the instigator of many changes, developments and innovations not least the genesis of the US Coast Guard and SOLAS. Among the innovations of how to detect obstructions at sea, like an iceberg, was one conceived by a Canadian born radio engineer, Reginald Fessenden working as a consultant to the Submarine Signal Company to enhance their system of underwater bells for shore-based stations, buoys, and light ships and for sound detection on ships.
During the Cold War, nuclear submarines performed the greatest public service of all: prevention of a third world war. History shows that they succeeded; the Cold War ended peacefully, but for security reasons, only now can this story be told.
Eric Thompson is a career nuclear submarine officer who served from the first days of the Polaris missile boats until after the end of the Cold War. He joined the Navy in the last days of Empire, made his first sorties in World War II type submarines and ended up as the top engineer in charge of the navy's nuclear power plants. Along the way, he helped develop all manner of kit, from guided torpedoes to the Trident ballistic missile system. In this vivid personal account of his submarine operations, he reveals what it was like to literally have your finger on the nuclear button.
In his journey, the author leads the reader through top-secret submarine patrols, hush-hush scientific trials, underwater weapon developments, public relations battles with nuclear protesters, arm-wrestling with politicians and the changing roles of females and homosexuals in the Navy. It is essentially a human story, rich in both drama and comedy, like the Russian spy trawler that played dance music at passing submarines. There was never a dull moment.
Behind the lighter moments was a deadly serious game. This, the inside story of Britain's nuclear deterrent, reveals the secretive life of submarines and the men who served on them; they kept their watch, and by maintaining the threat of 'Mutually Assured Destruction' helped keep Britain and the world safe.
17 pages added or updated in the last 1 month
Please help to maintain this site by reporting any Errors, Broken Links, Information or Site Issues on this page using this button
If you find this site useful, please consider supporting my work with a small Donation.
Please Note: Donations made using this option go directly to the site owner and not to the Submariners Association.
Thankyou for your support.

