100 YEARS OF BARROW-BUILT RN SUBMARINES, 1901-2001
L, H AND R CLASSES, 1916-1945
L CLASS SUBMARINES
1916 - 1945
Delighted with the success of the E Class submarines, the Admiralty decided, in 1916, to revert to the saddle tank type of construction, but incorporating the lessons learned from war experience. Two submarines to a new Admiralty design were ordered from Vickers in February 1916 and, being practically elongated Es, they were called E57 and E58. However, overall improvements so distinguished the design that a new class title was adopted, the L Class, and the two boats were later renamed L1 and L2.
By December 1916, a total of 34 L Class submarines had been ordered, but of these only 27 were commissioned - L28 to L32 were broken-up after commencement and L34 and L35 were cancelled. L13 was never ordered, presumably for 'superstitious' reasons (memories of the K13?) Eighteen of the class were built at Vickers, three of which were completed in other yards.
L Class submarines can be divided into three groups: L1 to L8 with 18-inch bow and beam tubes; L14, L17 and L24 to L27, which were fitted as minelayers, with 21-inch bow tubes; and L9 to L33 (excluding the minelayers) which had 21-inch bow tubes and 18-inch beam tubes.
In addition to torpedo armament, the class carried a gun mounted on the superstructure forward of the bridge. Although the earlier boats (L1 to L8) carried a 3-inch HA gun, all the class were eventually fitted with a 4-inch gun of various descriptions - for a three-man increase in the complement: this increase meant that the L boats had a 38-man crew, but even so, they carried only one 12ft 6in collapsible lifeboat.
The L Class were the first submarines to carry some of the normal fuel stowage in external tanks. Although only about 20 tons of fuel was carried in two lightly-constructed tanks, this started the practice, which was developed in the 1920s, of carrying a large amount of fuel externally.
The main engines of the class were two 12-cylinder diesels, giving a total of 2400 bhp at 380 rev/min. Some authorities quote 2600 bhp, but this was the bench test power of the engines. L Class submarines carried 336 cells in three battery tanks, grouped to allow working at 220 volts in series and 110 volts in parallel, producing submerged power for four main motors of the open shunt wound double-armature type, developing a total of 1600bhp at 300 rev/min for 11/2 hours. Also, an auxiliary drive consisting of a 20hp motor, driving the starboard shaft through a worm drive, could give a slow-running submerged speed of 1.75 knots.
A surface speed in excess if 17 knots was hoped for in the L Class and, even when carrying additional fuel in the external tanks, there is no doubt that this speed was attained. The first boat on trials, L1, actually obtained 17.2 knots and, in 1930, 17.6 knots was given as the design surface speed for the class. Although a designed submerged speed of 11 knots was anticipated in L1, the fitting of a 5ft 6in high fixed bridge screen reduced this to 10.5 knots.
Whilst it has been stated that the designed diving depth of the L Class was 250 feet, the officially used maximum diving depth, in 1925, was 150 feet - based on the age of the boats, their wartime construction, etc. However, depths, in service, of more than 250 feet have been recorded and, on one occasion, L2 accidentally submerged to 300 feet and, except for minor faults, withstood the pressure.
Of the L Class, only one was lost during the war - L10, in the North Sea. In August 1923, L9 foundered in Hong Kong harbour in a typhoon and was later salvaged, but was not refitted. In January 1924, L24 was accidentally rammed and sunk off Portland by the battleship HMS Resolution. At the time, prolonged efforts were made to salvage her, and a team of German divers, with a new type of diving suit that enabled them to work in deeper waters, was brought over.
Unfortunately, the strong underwater currents proved too difficult and the L24 still lies where she sank. In October 1945, L23 was the last L boat to be taken out of service - 28 years after she was laid down - thus reflecting the success of the class.
The building of the L boats led to the construction of the L50 Class, which was the L Class modified to give increased armament. Although none were built at Vickers, a total of 25 L50 submarines were ordered from seven yards, but of these only seven were completed.
H21 CLASS SUBMARINES
1917-1945
While L Class submarines were under construction, Vickers received an order, in January 1917, to build 12 boats to the American H Class design. Twenty boats of this class had been contracted from the Bethlehem Steel Works, USA in November 1914 for the Royal Navy. Fourteen had been delivered (H1 to H12, H14 and H15) - whilst the other six had been forfeited to Chile as compensation for warships seized in 1914. H14 and H15 were transferred to the Royal Canadian Navy in April 1919.
The British H boats, known as the H21 Class, were a modification of the American design, and accommodated a heavier torpedo armament (21-inch bow tubes replacing 18-inch tubes) which increased the overall length of the class by over 21 feet. Construction was speeded up by using engines, main motors and other fittings obtained from America. The Vickers-built first-of-class boat, H21, was completed in January 1918 - 11 months after being laid down.
In June 1917, further orders were given to five other yards for 22 additional H21 submarines (H33 to H54), with their engines and motors being made in England to the American H Class design. Ten of these boats were subsequently cancelled when it was decided, in October 1917, to construct 12 new R Class submarines.
The H21 Class were the first Royal Navy twin-shafted single-hulled submarines, and their American-designed eight-cylinder vertical single armature diesel engines produced a total of 480bhp. Also of American design, their main motors, powered by 120 battery cells, produced 620bhp for one hour and had a continuous rating of 320bhp.
As the H21 Class employed the same engines and main motors as the American H boats, but had an increase in displacement of over 70 tons, quoting the American design speeds of 13 knots surfaced and 10.5 knots submerged was obviously optimistic. In service, actual speeds of 11.5 knots surfaced and 9 knots submerged were recorded.
Although built for service in the First World War, the only H21 Class submarines to be lost on active service were, ironically, during the Second World War - over 20 years later. The H49 was depth charged off the Dutch coast in October 1940 and the Barrow-built H31 was lost, presumed mined, in the Bay of Biscay on Christmas Eve 1941.
The last H21 Class submarine to be taken out of service was the H34 - in October 1945 - 28 years after she was laid down at Cammell Laird.
1917-1934
R Class submarines, the forerunners of the modern-day hunter-killers, were built on the premise that a submarine with an exceptionally high submerged speed and with the ability to launch a number of torpedoes might be able to overtake and sink the enemy.
In October 1917, 12 R boats were ordered from five yards and R7 was the first to be completed, at Vickers, in June 1918 within nine months of order. Vickers also constructed R8. A further. two boats that were to be built at Pembroke Dockyard, R5 and R6, were cancelled before launch.
The R boats' surface speed of 9.5 knots was attained from one 240 bhp engine of the H Class type and their two main motors, driven by 220 battery cells, generating 1200bhp. Also, the fact that the class could reach a submerged speed of 15 knots, which remained a record until the closing stages of the Second World War, was partly due to their lightened superstructure, which was cut to a bare minimum, and a streamlined fish-shaped hull.
From war experience, designers became rather optimistic in their assessment of diving depths and the designed diving depth of the R Class was given as 250 feet, but the operational diving depth would have been fixed at 150 feet.
The R Class were the first Royal Navy submarines to be fitted with six 18-inch bow torpedo tubes, which was a powerful torpedo armament for the size of boat. One spare torpedo was allowed for in the design, but during the war, six spares were stowed at the expense of the Senior Ratings' accommodation. Originally it was intended to fit a 4-inch gun forward of the bridge, but this was never adopted, as it would have had an adverse effect on submerged speed, which was the main characteristic of the design.
Having a greater submerged radius than most submarines of the period, the R boats used five hydrophones to detect submerged enemy vessels: had they been fitted with a better detection device, the development of the modern submarine may have gone ahead more quickly. An R boat is credited with torpedoing a U-Boat in October 1918 - had the torpedo exploded, the R boats might have earned more respect instead of being thought of as curiosities.
MAIN PARTICULARS L1 to L8 L9 to L33 H21 Class R Class
Length overall 231 ft 1 in 238 ft 7 in 171 ft 9 in 163 ft 9 in
Beam 23 ft 5 1/2 in 23ft 5 1/2 in 15 ft 9 in 15 ft 9 in
Depth, pressure hull 15 ft 9 1/4 in 15ft 9 1/4 in 15ft 4 in 15 ft 3 in
