The small size of the MGBs, and their high speed, made them difficult targets for German E-boats, though, like their opponents, they were limited by heavy weather, because they did not provide a stable-enough platform to aim the guns.
The later 71.5 ft (21.8 m) short MGBs would have two heavy weapon locations (a pom-pom forward and twin 20mm Oerlikon aft), outmatching contemporary enemy boats of larger size.
The outstanding feature of most short MGBs was their very high speed of 36–40 kn (67–74 km/h; 41–46 mph), enabling them to work with, or in place of, MTBs on offensive sweeps.
A major feature of the long MGBs was that they carried two heavy guns as well as numerous lighter weapons; the 27 kn (50 km/h; 31 mph) Type 'C' began to introduce the versatile and hard-hitting Vickers pom-pom to Coastal Forces' inventory, as well as carrying one Rolls-Royce 2-pdr gun (40mm) on the aft bandstand.
MGB flotillas (particularly under Robert Hichens' command) also developed the tactic of accompanying MTBs on their patrols across the North Sea to attack enemy coastal shipping.
The larger and heavier Type 'C' were slower than the short boats, so that they were assigned much more frequently to defensive and convoy escort duties, and clandestine work such as extraction of Allied agents/escapees from occupied France.
Operating from island bases they patrolled along the western coast of Italy, attacking small coastal ships and E-boats until mid-1944.
63-foot MGBs (numbered 40–45) were of 24 t standard displacement and powered by 2-shaft Rolls-Royce petrol engines developing 2,200bhp for a top speed of 40 knots.
They dispensed with the torpedo tubes and shipped an armament of 1 × pom pom in MkXVI mounting, 1 × twin Oerlikon in MkV mounting, 2 × twin HMGs and a 6-pdr Hotchkiss gun Only 502, 503 and 509 were completed as MGBs; 504-508 were completed as the fast blockade runners Master Standfast, Gay Corsair, Gay Viking, Hopewell and Nonsuch.
[4] She was built by the British Power Boat Company, Hythe, launched in 1942, and served at the Normandy landings (although renumbered as MTB 416 by this time, as the MGB designation had been largely abolished by the RN late in the war).