Fairmile A motor launch

The Fairmile A motor launch was a coastal motor launch designed by Norman Hart for the Fairmile Marine for the Royal Navy in World War II. The prototype ML 100 was privately built by the British industrialist Noel Macklin, who placed an order for this craft on 27 July 1939 with Woodnut's boatyard at St Helens. The Admiralty placed an order for a series of 25 boats to this design on 22 September, including the prototype under construction. The twelve boats completed to this initial design were numbered ML 100 to ML 111, while the thirteen other boats ordered on 22 September were re-ordered to the Admiralty's own Fairmile B design.

Development
Shortly before the Second World War the British industrialist Noel Macklin submitted to the Admiralty an innovative plan for the series production of a motor launch (vessels for harbour defence and submarine chasing). The design used prefabricated parts, which allowed various small concerns, such as furniture and piano manufacturers, to produce the individual components. These components could then be assembled in separate shipyards. The hull was to be made of plywood frames divided into nine watertight compartments, with double diagonal mahogany planking forming the outer skin.

The final design was a 110-foot, hard-chine boat of planing form, optimised for speed at the expense of range as befitted the intended coastal sub-chaser role, although the turning circle would be larger than hoped for as a result of the hard chines. The cabin was located well forward, leaving a large working space aft for the handling of depth charges and guns. The Admiralty rejected the concept, and so the prototype was built as a private venture. In July 1939, two months before the outbreak of war, the Admiralty had a change of heart and purchased the prototype. Following the outbreak of war, they awarded Macklin's Fairmile Marine company a contract on 22 September to have built twenty-four further Type A Fairmiles, using a variety of separate shipyards. While these launches were on order, an improved Type B design came 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. Thus Fairmile was instructed to complete the last thirteen of the order (ML 112 to ML 124) to the new variant design, so that only twelve Type A (including the prototype) were completed.

Service
The first vessel (ML100) was not completed until May 1940 because of handling problems at low speeds, although the subsequent boats had all entered service by July. Their role was to be anti-submarine escorts in coastal waters, but, once the better Fairmile B motor launches began to enter service in the autumn of 1940, the Type A boats were converted to minelayers.