A WW I motor launch - ML 59
Class overview
Operators Royal Navy
In commission1915–1920s
General characteristics ML.1–50 series
TypeMotor launch
Displacement34 t
Length75 ft (23 m)
PropulsionPetrol engine
Speed19 kn (35 km/h)
General characteristics ML.51–550 series
TypeMotor launch
Displacement37 t
Length86 ft (26 m)
PropulsionPetrol engine
Speed19 kn (35 km/h)
General characteristics ML.551–580
TypeMotor launch
Displacement37 t
Length80 ft (24 m)
Speed19 kn (35 km/h)
  • 1 × 13-pdr gun
  • later replaced with 1 × 3-pdr

A motor launch (ML) is a small military vessel in Royal Navy service. It was designed for harbour defence and submarine chasing. Similar vessels were used by the Royal Air Force for armed high-speed air-sea rescue. Some vessels for water police service are also known as motor launches. Motor launches were slower than motor torpedo boats and motor gun boats

World War I service

Although small by naval standards, it was larger than the preceding steam or diesel-engined harbour launches of 56 ft and coastal motor boats of 40 and 55 ft length. The first motor launches entered service in the First World War. These were five hundred and eighty 80-foot-long (24 m) vessels built by the US Elco company for the Admiralty, receiving the numbers ML-1 to ML-580. They served with the Royal Navy between 1916 and the end of the war, defending the British coast from German submarines.[1] Some of the earliest examples, including ML 1, also served in the Persian Gulf from June 1916. After the Armistice of 11 November 1918 a flotilla of 12 Royal Navy motor launches travelled down the Rhine performing duty as the Rhine Patrol Flotilla.[2] The only known surviving example of a World War I era motor launch is ML-286, which now lies in a poor condition on the banks of the River Thames.

World War II types

Royal Norwegian Navy Fairmile B motor launches off Dover circa 1940-1941.
Type Length Weight Speed Built Total Lost Designed for
Fairmile A motor launch 110 ft (34 m) 57 tons 25 knots (46 km/h) 1939 12 Submarine chasing, later minelaying
Fairmile B motor launch 112 ft (34 m) 85 tons 20 knots (37 km/h) 1940–45 1,284 Submarine chasing, many later roles including air-sea rescue
Harbour defence motor launch 72 ft (22 m) 54 tons 12 knots (22 km/h) 1940–45 486 47 Defending harbours; anti-submarine
BPBC Type Two 63 ft high speed launch "Whaleback" 63 ft (19 m) 21.5 tons 36 knots (67 km/h) 1940–42 70 RAF air-sea rescue downed aircrew, particularly in the English Channel

The BPBC Type Two was succeeded by the Type Three 68 ft "Hants and Dorset".

Post-war, many motor launches were taken on as pleasure boats. A number of them are on the National Register of Historic Vessels.[3]

See also


  1. ^ Gardiner, p. 101
  2. ^ Jeffrey Charles. "The Rhine Patrol Flotilla Part I: Establishment of the Flotilla".
  3. ^ Gardiner and Chesneau, p. 71