The K class was a series of steam-propelled attack submarines built for the Royal Navy, and launched between 1916 and 1919. This was
another attempt for achieving a submarine capable of accompanying the surface fleet at its regular cruising speed. This goal was
indeed achieved, for these submarines could reach a speed of 24 knots while in surface, but this came with a high price: their poor
maneuverability and their machinery of convoluted conception caused an abnormal number of fatal accidents. These defects were
accentuated by the proximity to the surface fleet imposed by their role. Given how dangerous a submarine was and how difficult was to
make a precise identification of a submerged vessel, these units were prone to friendly fire. On the other hand, the scarce visibility
from inside a submarine rendered these vessels as unsuitable for navigating in a close formation.
These submarines were fitted with two petrol boilers, having each of them a small chimney which, vertically, led to a water well. These
boilers, for achieving a maximum performance, were provided with numerous vents which constituted a serious danger. As a contemporary
submarinist said, the submarines had "too many damn holes". A small obstruction, a piece of rope, or anything similar, was enough to
leave open one of so many openings, putting into serious danger a submarine ready for immersion.
One of the most serious incidents happened during the Battle of May Island the 31st January 1918, when two flotillas of K-class submarines
which were operating alongside some battlecruisers, suffered a series of collisions. The K4 was sunken by the K6 while the K7 was rammed
by one of the battlecruisers. A subsequent investigation revealed that the disaster was triggered by a blocked rudder in the K22 (ex K13,
rebaptized after her maiden voyage in which many of her crewmen drowned). Due to their notable size, these units were hardly maneuverable.
They were in fact the largest submarine units of that time, even larger than a German U-cruisers.
In the illustration we can see the K11; note the four torpedo launchers at prow, the two side openings amidships for the transverse torpedo
launchers, the external torpedo tubes installed in the large superstructure, the two funnels and the two 102-millimeter deck cannons.
There existed an improved version of the K class, which eliminated many defects from the original version. A new raised bow contained
a ballast deposit to allow for a quicker immersion. During the war six units were lost due to the aforementioned technicals problems.
The largest part of these submarines was scrapped between 1921 and 1926 but the K26, the only unit of improved version completed, survived
until 1931, when she was broken up because her displacement exceeded the limits set by the London Naval Treaty in 1930.
K class: 18 units (K1 to K17, K26)
Type: Attack submarine
Length: 103 meters
Beam: 8.1 meters
Draught: 6.4 meters
Displacement (surfaced): 1980 tonnes
Displacement (submerged): 2566 tonnes
Propulsion: 2 x shaft, 2 x steam turbine Brown-Curtis/Parsons 10500 horsepower, 2 x petrol boiler Yarrow,
4 x electric motor 1440 horsepower, 1 x Diesel-electric group Vickers 800 horsepower 600 kilowatt
Speed (surfaced): 24 knots (44 kilometers/hour)
Speed (submerged): 8 knots (14.8 kilometers/hour)
Range (surfaced): 12500 nautical miles (20000 kilometers) at 10 knots
Range (submerged): 40 nautical miles (64 kilometers) at 4 knots
Test depth: 60 meters
Armament: 8 x 457-millimeter torpedo tubes (4 at prow, 4 in transverse), 16 x torpedo, 2 x 102-millimeter deck cannon