Fairmile B motor launch

The Fairmile B motor launch (often abbreviated to 'ML') was a large class of motor launch built by British boatbuilder Fairmile Marine and others during the Second World War to meet the Royal Navy's coastal operation requirements. While the Type A motor launch had been designed entirely by Fairmile, the Type B design had come from Bill Holt, head of the Admiralty's DNC Boat Section. The hard-chine hull of the Type A had exhibited seakeeping and handling limitations, but Holt's round-bilged design for the Type B was a far more seaworthy form. Like all Fairmile boats, production of the Type B was based on total prefabrication so individual components could be contracted out to small factories for production and these arranged as kits that would be delivered in stages to various boatyards for assembly & fitting out on a 'just-in-time' basis. Accordingly, the detailed design work for the Type B was taken on by Fairmile and modified to suit their kit fabrication principle - they then also handled production of component parts. Altogether approximately 650 boats were built between 1940 and 1945. Like the Type As, the Type Bs were initially intended as submarine chasers, so the boats were fitted with ASDIC (sonar) as standard. Their main armament initially reflected their anti-submarine focus, with 12 depth charges, a single QF 3-pounder Hotchkiss gun forward, and one set of twin 0.303-in Lewis or GO machine guns (frequently increased in number by the crew); early boats often received a Holman projector amidships. A common upgrade to gun armament by 1942-43 in many early boats was to add an aft bandstand mounting for either a 2-pdr Rolls gun or a 20mm Oerlikon cannon. The specifications given are for the original 1940 British version. As the war moved on, the vessels were adapted to other roles and the armament was modified and upgraded such as the replacement of the 3-pounder with one or more 20 mm Oerlikon cannon and removal of the ASDIC dome for more clearance as minesweepers. Some boats were configured as motor torpedo boats.