Originally designed for the RN by W.J. Holt of the Office of the Admiralty and Marine Affairs and built by British boatbuilder Fairmile Marine, during the Second World War, eighty-eight Fairmile B motor launches, with slight modifications for Canadian climatic and operational conditions, were built in Canada for service with the RCN in home waters.
While they flew the White Ensign, the Canadian Fairmiles were not commissioned ships of the RCN, but rather listed as a tenders to the escort depot ship HMCS Sambro.
As one former Q-Boat captain described them, "sheathed for operation in ice and displacing 100 tons, they were indeed veritable 'Little Fighting Ships'."

Originally designated and painted up as CML (coastal motor launch) 01–36, the Canadian Fairmile B was built of double mahogany wood with an eight-inch oak keel.
Based on a line of destroyer hulls, they arrived in prefabricated kits, ready to be assembled for the RCN by thirteen different boatyards.
In contrast to the British built boats, the Canadian Fairmiles were narrower, had a greater draught, and were slightly more powerful giving the Canadian MLs a two knot speed advantage over the British boats.

With a fuel capacity of 2,320 gallons of 87 octane gasoline, the early Fairmiles (Q050 to Q111) were powered by two 650 hp engines, could reach a top speed of 20 knots (max), 16.5 knots sea speed and a range of 1925 miles at 7.5 knots.
Later versions (Q112 to Q129) were fitted with larger 700 hp engines able to achieve a top speed to 22 knots (max), with a range of 1925 miles at 7.5 knots.
Crewed by two or three officers and 14 sailors, accommodation on the Fairmiles was thought to be "cramped but comfortable".

Another unique design feature of the Fairmile B was that with forty-eight hours notice each boat could be reconfigured to serve in a different role.
Fitted with steel strips and tapped holes to ease equipment swaps, weapons and specialist gear such as torpedo tubes, mines, depth charges, and guns could be quickly stripped and attached to the boat.
In two days, a Fairmile could have its weapons and equipment reconfigured to serve as an escort, minesweeper, minelayer, navigation leader, coastal raider, patrol boat, ambulance or rescue launch. "
Armament consisted of three 20 mm Oerlikon guns, mounted forward, aft and amidships; two .303 machine-guns; one 9 mm Sten gun; two .303 rifles; three .45 revolvers; and 20 depth-charges of 300 lbs each, including eight fitted for the "Y" gun.
Each boat was equipped with sonar, radar and WIT."
Originally designed for the RN by W.J. Holt of the Office of the Admiralty and Marine Affairs and built by British boatbuilder Fairmile Marine, during the Second World War, eighty-eight Fairmile B motor launches, with slight modifications for Canadian climatic and operational conditions, were built in Canada for service with the RCN in home waters. While they flew the White Ensign, the Canadian Fairmiles were not commissioned ships of the RCN, but rather listed as a tenders to the escort depot ship HMCS Sambro. As one former Q-Boat captain described them, "sheathed for operation in ice and displacing 100 tons, they were indeed veritable 'Little Fighting Ships'."
Originally designated and painted up as CML (coastal motor launch) 01–36, the Canadian Fairmile B was built of double mahogany wood with an eight-inch oak keel. Based on a line of destroyer hulls, they arrived in prefabricated kits, ready to be assembled for the RCN by thirteen different boatyards. In contrast to the British built boats, the Canadian Fairmiles were narrower, had a greater draught, and were slightly more powerful giving the Canadian MLs a two knot speed advantage over the British boats.
With a fuel capacity of 2,320 gallons of 87 octane gasoline, the early Fairmiles (Q050 to Q111) were powered by two 650 hp engines, could reach a top speed of 20 knots (max), 16.5 knots sea speed and a range of 1925 miles at 7.5 knots. Later versions (Q112 to Q129) were fitted with larger 700 hp engines able to achieve a top speed to 22 knots (max), with a range of 1925 miles at 7.5 knots. Crewed by two or three officers and 14 sailors, accommodation on the Fairmiles was thought to be "cramped but comfortable".
Another unique design feature of the Fairmile B was that with forty-eight hours notice each boat could be reconfigured to serve in a different role. Fitted with steel strips and tapped holes to ease equipment swaps, weapons and specialist gear such as torpedo tubes, mines, depth charges, and guns could be quickly stripped and attached to the boat. In two days, a Fairmile could have its weapons and equipment reconfigured to serve as an escort, minesweeper, minelayer, navigation leader, coastal raider, patrol boat, ambulance or rescue launch. "Armament consisted of three 20 mm Oerlikon guns, mounted forward, aft and amidships; two .303 machine-guns; one 9 mm Sten gun; two .303 rifles; three .45 revolvers; and 20 depth-charges of 300 lbs each, including eight fitted for the "Y" gun. Each boat was equipped with sonar, radar and WIT."
Coastal Forces of the Royal Canadian Navy