RN Submarines

Pennant Numbers

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.

Pennant Numbers

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.