M15-class monitor

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HMS M21
Class overview
NameM15 class
Operators Royal Navy
Preceded byGorgon class
Succeeded byM29 class
In service1915–1959
Completed14
Lost4
General characteristics
TypeMonitor
Displacement540 tons
Length177 ft 3 in (54.03 m)
Beam31 ft (9.4 m)
Draught6 ft 9 in (2.06 m)
Propulsion
  • 2 shafts
  • Triple-expansion
  • 800 hp (600 kW)
  • 4 shaft
  • Bolinder 4-cylinder semi-diesel
  • 640 hp (480 kW)
  • 4 shafts
  • Campbell 4-cylinder paraffin engines
  • 560 bhp (420 kW)
Speed11 knots (20 km/h; 13 mph)
Complement69
Armament

The M15 class comprised fourteen

monitors of the Royal Navy
, all built and launched during 1915.

Design

The ships of this class were ordered in March, 1915, as part of the

, all received the Mk VI mounting.

During September 1915, the 9.2 inch guns of HMS M24, M25, M26 and M27 were removed for use as artillery. These were replaced by

, M26 received one of Swiftsure's spare guns. M27 received 6-inch (M27) guns.

M21 and M23 also had their 9.2-inch gun removed in 1917, receiving 7.5-inch guns from the decommissioned pre-dreadnought Swiftsure.

The class used a mixture of propulsion methods. M21 and M22 were fitted with conventional triple-expansion steam engines, M24 was fitted with four-cylinder paraffin engines, and the remainder received Bolinder four-cylinder semi-diesel engines.

Admiral Reginald Bacon, who had commanded several of the M15 class in the Dover Patrol, wrote about his experiences with the ships of the patrol in 1919. While generally positive about the performance of the design, he noted that they had a tendency to roll, using a specific occasion with M25 as an example;

"The M25, while in the mouth of the Thames at anchor, rolled 180 degrees in ten seconds - that is, she made two complete rolls of 45 degrees each way, each occupying only five seconds."[1]

Service

M25, M26, M27 and M28 served in the Dover Patrol from 1915 to 1918. The remainder served in the Mediterranean from 1915, with M23 joining the Dover Patrol in June 1917 and M21 in October 1917.

As part of the

intervention into the Russian civil war M23, M24, M25 and M27 served in support of British and White Russian forces in the White Sea
in May to September 1919.

M22 was converted to a minelayer in 1920, whilst M23 became a drill ship, surviving until 1959.

Ships of the class

  • M15 - launched on 28 April 1915 and sunk by UC-38 on 11 November 1917.
  • M16 - launched on 3 May 1915 and sold 29 January 1920.
  • M17 - launched on 12 May 1915 and sold 12 May 1920.
  • M18 - launched on 15 May 1915 and sold 29 January 1920.
  • M19 - launched on 4 May 1915 and sold 12 May 1920.
  • M20 - launched on 11 May 1915 and sold 29 January 1920.
  • M21 - launched on 27 May 1915 and mined 20 October 1918.
  • M22 - launched on 10 June 1915, renamed Medea 1925 and sold December 1938
  • M23 - launched on 17 June 1915, renamed Claverhouse 1922 and sold 1959
  • M24 - launched on 9 August 1915 and sold 29 January 1920.
  • M25 - launched on 24 July 1915 and scuttled 16 September 1919
  • M26 - launched on 24 August 1915 and sold 29 January 1920.
  • M27 - launched on 8 September 1915 and scuttled 16 September 1919
  • M28 - launched on 28 June 1915 and sunk during the Battle of Imbros 20 January 1918

References

  1. ^ Bacon 1919, vol 1, p. 67.

Bibliography

External links