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The Fairmile D motor gun boat MGB 606
Class overview
Name	Fairmile D motor gun boat
Preceded by	Fairmile C motor gun boat
Planned	229
Completed	228
Cancelled	1
General characteristics
Displacement	As MTB 102 long tons (104 t) standard 118 long tons (120 t) full load As MGB 90 long tons (91 t) standard 107 long tons (109 t) full load
Length	115 ft (35 m)
Beam	20 ft 10 in (6.35 m)
Draught	4 ft 9 in (1.45 m) to 4 ft 11 in (1.50 m) mean deep load
Propulsion	4 × Packard 4M 2500 petrol engines, total 5,000 hp (3,728 kW)
Speed	29 knots (54 km/h; 33 mph) at full load
Range	506 nmi (937 km; 582 mi) at max revolutions 2,000 nmi (3,700 km; 2,300 mi) at 11 kn (20 km/h; 13 mph)
Complement	21
Armament	2 × single 6 pounder guns 4 × 20mm Oerlikon (2 × single, 1 × twin) 2 × twin .303 Vickers K machine guns 4 × light boat depth charges Searchlight TSA smoke generator
Notes	Armament for gunboat configuration as fitted to MGB 658 by the end of the war. Specifications from Conway's All the World's Fighting Ships 1922–1946. and Motor Gunboat 658

The Fairmile D motor torpedo boat was a type of British motor torpedo boat (MTB) and motor gunboat (MGB),^[1] conceived by entrepreneur Noel Macklin of Fairmile Marine and designed by naval architect Bill Holt for the Royal Navy. Nicknamed "Dog Boats", they were designed to be assembled in kit form mass-produced by the Fairmile organisation and assembled at dozens of small boatbuilding yards around Britain, to combat the known advantages of the German E-boats over previous British coastal craft designs. At 115 feet in length, they were bigger than earlier MTB or motor gunboat (MGB) designs (which were typically around 70 feet) but slower, at 30 knots compared to 40 knots.

Boats

1941 Original Programme

The first twelve boats were ordered on 15 March 1941, becoming MGB 601 to MGB 612. Six weeks later, another 28 boats were ordered on 27 April 1941, as MGB 613 to MGB 616, and ML 617 to ML 640, although these MLs were quickly reclassed as MGBs. The prefix for all boats (except early losses 622, 631 and 639) was reclassed from "MGB" to "MTB" in September 1943.

Eight of these boats (nos. 618, 619, 620, 623, 625, 626, 627 and 631) were handed over to the Royal Norwegian Navy in 1942, manned by free Norwegian personnel and formed into the 30th MTB Flotilla under Lt. Ragnvald Tamber. After being worked up at HMS Bee shore base at Weymouth, they were based at Lerwick in the Shetland Islands, and deployed for numerous operations along the Norwegian coast.^[2] MTB 631 was captured by the Germans in March 1943 and replaced by MTB 653.

The last eight of the programme (boats nos. 633 to 640) were chosen for Mediterranean operations; they were worked up at HMS Bee at Weymouth before proceeding to Milford Haven, where they were formed into a new 32nd MTB Flotilla under the command of Lt. P. E. Stewart Gould; they were fitted with extra temporary fuel tanks bolted to the upper deck (raising their fuel capacity by 3,000 gallons to 8,000 gallons of 100 octane petrol for the long passage to the Mediterranean), and proceeded in groups to Gibraltar in March/April 1943.

1941 Supplemental Programme

A further 60 boats were ordered in November 1941, numbered from 641 up to 700, of which 16 ordered on 18 November had the prefix of "MGB" (numbers 641 to 648, 657 to 663, and 674), and 44 ordered on 28 November originally had the prefix of "ML" (numbers 649 to 656, 664 to 673, and 675 to 700), although the MLs were quickly reclassed as MGBs. All of these (except early losses) were reclassed as "MTB" in September 1943. However, from No. 697 onwards, the boats were classified as combined "MTB"/"MGB"s.

As with the final eight boats of the preceding programme, 24 boats were chosen for Mediterranean operations; they were worked up at HMS Bee at Weymouth before proceeding to Milford Haven, where they were formed into three new flotillas as follows (with initial flotilla commanders in parentheses):

• 19th MGB Flotilla (under Lt E.M. ("Mickey") Thorpe): boats nos. 641 to 648 inclusive.
• 33rd MTB Flotilla (under Lt-Cmdr Ronald R. W. Ashby): boats nos. 649, 651, 654, 655, 656, 665, 667 and 670.
• 20th MGB Flotilla (under Lt-Cmdr Norman H. Hughes): boats nos. 657 to 663 inclusive, plus 674 (although 674 only joined later).

As before, they were fitted with extra temporary fuel tanks bolted to the upper deck (raising their fuel capacity by 3,000 gallons to 8,000 gallons of 100 octane petrol for the long passage to the Mediterranean), and proceeded in groups to Gibraltar in March/April 1943.

Note: (a) 674 was the final boat ordered as a MGB, and is thus shown out of numerical sequence.

1942 Original Programme

Another 23 boats were ordered on 7 April 1942 as MTB 701 to MTB 723.