1. History

MTBs in the Mediterranean, February 1945. https://handwiki.org/wiki/index.php?curid=1153070

MTBs were designed for high speed, operating at night, low speed ambush (to keep noise low and to produce no wake) and manoeuvrability on the water; this was to enable them to get close enough to launch their torpedoes at enemy vessels. With no significant armour, the boats relied upon surprise and their agility at high speed to avoid being hit by gunfire from bigger ships.

The British and Italian navies started developing such vessels in the early 20th century, shortly before the beginning of the First World War. Italian MAS boats were comparatively small, at 20-30 tons displacement. MAS 15 was the only motor torpedo boat in history to sink a battleship, the Austro-Hungarian vessel Szent István in 1918.

British torpedo boats of the First World War were small at only around 15 tons and were known as Coastal Motor Boats. In the Second World War, British MTBs were operated by Coastal Forces. A similar size boat with a different role in the Second World War was the BPB 63 ft (19 m) high-speed launch used by the RAF for air-sea rescue operations.^[1] The last MTBs in the Royal Navy were the two Brave-class fast patrol boats of 1958 which were capable of 50 knots (93 km/h).

2. Specifications

Many boats were designated MTBs. A variety of designs were adopted and built. For instance, a 55 ft (17 m) type, capable of 40 kn (46 mph; 74 km/h), was shown in 1930.^[2]

2.1. Vosper Private Venture Boat

The Vosper private boat was designed by Commander Peter Du Cane CBE, the managing director of Vosper Ltd, in 1936. She was completed and launched in 1937. She was bought by the Admiralty and taken into service with the Royal Navy as MTB 102.

• Length: 68 ft (21 m)
• Beam: 19 ft 9 in (6.02 m)
• Draft: 3 ft 9 in (1.14 m),
• Powerplant: 3 Isotta Fraschini 57-litre petrol engines
• Power: 3,300 hp (2,500 kW; 3,300 PS)
• Speed: 48 kn (55 mph; 89 km/h) (light), 43 kn (49 mph; 80 km/h) (full load)
• Crew: 2 officers, 10 men.
• Armament:
  • Two 21 in (533 mm) torpedo tubes (depth charges, machine guns and 20mm Oerlikon were trialled on her)

MTB 102 was the fastest wartime British naval vessel in service. She was at Dunkirk for the evacuation and carried Winston Churchill and Dwight Eisenhower when they reviewed the fleet before the Invasion of Normandy.

2.1. British Power Boat 60 ft MTB

They were based on the British Power Boat rescue craft and were originally designed for the Royal Air Force but reduced to 60 ft (18 m) in length. They could carry two 18-inch (457 mm) torpedoes and achieve a maximum speed of 33 kn (38 mph; 61 km/h). The Royal Navy ordered their first (of a total of 18) in 1936. These entered service as MTB numbers 1 to 12 and 14 to 19. In the early days of the war, they were painted with different numbers and photos distributed to the press to give the impression the Royal Navy had more than they actually did. One photo was sent to the American monthly Popular Science showing the number twenty-three. ^[3]

2.2. Vosper 70 ft Motor Torpedo Boat

Although various boat lengths were produced by Vosper for the Royal Navy, the "70 ft" boat was produced from 1940. The design was produced with modifications as MTBs 31-40, 57-66, 73-98, 222-245, 347-362, 380-395 and 523-537.

Using three Packard V1-12 marine engines, they were capable of around 37 kn (43 mph; 69 km/h). Early models carried two 21-inch (533 mm) torpedo tubes, two 0.50 in (13 mm) machine guns and two 0.303 in (7.7 mm) machine guns. They could also carry four depth charges.

2.3. Vosper Types 1 and 2

Between 1943 and 1945, two Vosper designs appeared, the "Vosper type I 73ft" and the type II.

Vosper type I

• Length: 73 ft (22 m)
• Engine: 3 Packard 12M engines for a total of 4,200 hp
• Speed: 40 knots (74 km/h)
• Range: 470 nmi (870 km) at 20 knots (37 km/h)
• Displacement: 47 t
• Armament:
  • Four 18-inch (457 mm) torpedo tubes
  • Oerlikon 20 mm cannon
  • Two 0.303 in Vickers K machine guns (optionally two Vickers .50 machine guns)
• Crew: 13

Vosper type II

This design remained in use after the war.

• Length 73 ft (22 m)
• Engine 4,200 hp
• Speed 40 knots (74 km/h)
• Range 480 nmi (890 km) at 20 knots (37 km/h)
• Displacement 49 t
• Armament
  • Two 18-inch (457 mm) torpedoes
  • QF 6 pdr (57mm, 2.24 inch) Mark IIA^[4]
  • 20mm Oerlikon
  • Two 0.303 Vickers MG
• Crew 13

2.4. Canadian MTBs

MTB-460 of the Royal Canadian Navy. https://handwiki.org/wiki/index.php?curid=1683298

These boats were used by the Royal Canadian Navy 29th MTB Flotilla. Originally designed as Motor Gun Boats (MGBs) carrying a 6-pounder (57mm, 2.24 inch) to engage enemy small craft, they were re-designated Motor Torpedo Boats.

Scott-Paine type G 70 foot boat.

• Manufacturer: British Power Boats, Hythe
• Displacement: 55 tons
• Overall length: 72 ft 6 inches (21 m)
• Breadth: 20 ft 7 inches (6.3 m)
• Draught: 5 ft 8 inches (1.7 m)
• Maximum speed: 38–41 kn (44–47 mph; 70–76 km/h) (new)
• Armament:
  • auto-loading QF 6-pounder (57mm, 2.24 inch) gun
  • Two 21-inch (533 mm) torpedo tubes (two torpedoes)
  • .303 or .50 Vickers machine guns
  • 20mm Oerlikon or 40 mm Bofors gun
• Powerplant – three Rolls-Royce or Packard 14M supercharged V-12 engines
  three shafts
• Power – 3,750 hp total
• Range – 140 nmi (260 km) radius of action at 25 kn (29 mph; 46 km/h)^[5]

3. Post-war Usage

After the end of World War II a number of Royal Navy vessels were stripped and sold for use as houseboats. These included Motor Gun Boats as well as MTBs. Many of these were moored in Langstone Harbour, Littlehampton, Hayling Island and Wootton Creek, although most have now disappeared from these locations. More MTB houseboats can be found at Shoreham-by-Sea (West Sussex), Cobden Bridge (Southampton) and Bembridge (Isle of Wight).^[6]