on Pennant Numbers
These were used for visual
signalling purposes. Prior
to 1940 these identities consisted of two
Numeric Flags followed by an Alphabetic
Flag. In the Case of earlier Classes these
identities were painted on the
Conning Tower (eg
H and L-Classes). Later
Classes such as Rivers had no numbers painted
externally but had their name shown on
the Conning Tower.
Minelaying submarines also had no external
identity on their conning tower but
used Flag M
inferior to the allocated Numeric.
After 1940 the system was changed
and sequence of the Numeric and
Alphabetic Flags was
reversed. Identities used for pre-war build
were Flag N followed by two Numerics.
The submarines built during the war had
Numbers with Flag P followed by two or three Numerics.
This identity was used alone in place of a
Name for all purposes until early in
1943 when all existing wartime built
submarines were given names and future
builds were named before entering operational
service. Details of the Pennant Numbers are
shown in the List of builds
with earlier identities in parenthesis.
C l a s s
S u b m a r i
n e s
e n e r a l I n f o r m a t i
Originally intended for use as
this design was modified to provide gun
armament to enable their use in war for short
duties. Diesel-electric propulsion was used to
simplify the arrangements. One short-coming
was the absence of a
separate gun hatch which was provided in other
Classes to enable minimum time possible when
was required. All personnel outside the hull
had therefore to use the conning tower hatch.
build of this pre-war design took place during
Wartime builds were slightly larger)
x 21” Torpedo Tubes Forward with
four reload weapons.
x 3” Gun.
Later Builds had only four torpedo tubes.)
feet overall length, 16
feet beam and 12 feet 9 inches draught.
BHP Diesel and two 825 HP Electric Motors.
9-10 knots submerged
miles at 10 knots.
in later builds.