page_title: Torpedo boat
section_title: Motor torpedo craft
hierarchical_section_title: Torpedo boat / Motor torpedo craft
caption_attribution_description: English: Mtb 382 Underway.
context_page_description: A torpedo boat is a relatively small and fast naval ship designed to carry torpedoes into battle. The first designs were steam-powered craft dedicated to ramming enemy ships with explosive spar torpedoes. Later evolutions launched variants of self-propelled Whitehead torpedoes.
  These were inshore craft created to counter both the threat of battleships and other slow and heavily armed ships by using speed, agility, and powerful torpedoes, and the overwhelming expense of building a like number of capital ships to counter an enemy's. A swarm of expendable torpedo boats attacking en masse could overwhelm a larger ship's ability to fight them off using its large but cumbersome guns. A fleet of torpedo boats could pose a similar threat to an adversary's capital ships, albeit only in the coastal areas to which their small size and limited fuel load restricted them.
  The introduction of fast torpedo boats in the late 19th century was a serious concern to the era's naval strategists, introducing the concept of tactical asymmetric warfare. In response, navies operating large ships introduced smaller but more seaworthy ships to counter torpedo boats, mounting light quick-firing guns.
context_section_description: Before World War I steam torpedo boats which were larger and more heavily armed than hitherto were being used. The new internal combustion engine generated much more power for a given weight and size than steam engines, and allowed the development of a new class of small and fast boats. These powerful engines could make use of planing hull designs and were capable of the much higher speed of 30 to 50 knots (56 to 93 km/h) under appropriate sea conditions than displacement hulls. The boat could carry two to four torpedoes fired from simple fixed launchers and several machine guns.
  During the First World War, three junior officers of the Harwich Force suggested that small motor boats carrying a torpedo might be capable of travelling over the protective minefields and attacking ships of the Imperial German Navy at anchor in their bases. In 1915, the Admiralty produced a Staff Requirement requesting designs for a Coastal Motor Boat for service in the North Sea. These boats were expected to have a high speed, making use of the lightweight and powerful petrol engines then available. The speed of the boat when fully loaded was to be at least 30 knots (56 km/h) and sufficient fuel was to be carried to give a considerable radius of action.
  They were to be armed in a variety of ways, with torpedoes, depth charges or for laying mines. Secondary armament would have been provided by light machine guns, such as the Lewis gun. The CMBs were designed by Thornycroft, who had experience in small fast boats. Engines were not proper maritime internal combustion engines (as these were in short supply) but adapted aircraft engines from firms such as Sunbeam and Napier. A total of 39 such vessels were built.
  In 1917 Thornycroft produced an enlarged 60-foot (18 m) overall version. This allowed a heavier payload, and now two torpedoes could be carried. A mixed warload of a single torpedo and four depth charges could also be carried, the depth charges released from individual cradles over the sides, rather than a stern ramp. Speeds from 35–41 knots (40–47 mph; 65–76 km/h) were possible, depending on the various petrol engines fitted. At least two unexplained losses due to fires in port are thought to have been caused by a build-up of petrol vapour igniting.
  Italian torpedo boats sank the Austrian-Hungarian SMS Wien in 1917, and SMS Szent István in 1918. During the civil war in Russia, British torpedo boats made raids on Kronstadt harbour damaging two battleships and sinking a cruiser.
  Such vessels remained useful through World War II. The Royal Navy's Motor Torpedo Boats (MTBs), Kriegsmarine 'S-Boote' (Schnellboot or "fast-boat": British termed them E-boats), (Italian) M.A.S. and M.S., Soviet Navy G-5 and U.S. PT boats (standing for Patrol Torpedo) were all of this type.
  A classic fast torpedo boat action was the Channel Dash in February 1942 when German E-boats and destroyers defended the flotilla of Scharnhorst, Gneisenau, Prinz Eugen and several smaller ships as the passed through the Channel.
  By World War II torpedo boats were seriously hampered by higher fleet speeds; although they still had a speed advantage, they could only catch the larger ships by running at very high speeds over very short distances, as demonstrated in the Channel Dash. An even greater threat was the widespread arrival of patrol aircraft, which could hunt down torpedo boats long before they could engage their targets.
  During World War II United States naval forces employed fast wooden PT boats in the South Pacific in a number of roles in addition to the originally envisioned one of torpedo attack. PT boats performed reconnaissance, ferry, courier, search & rescue as well as attack and smoke screening duties. They took part in fleet actions and they worked in smaller groups and singly to harry enemy supply lines. Late in the Pacific War when large targets became scarce, many PT boats replaced two or all four of their torpedo tubes with additional guns for engaging enemy coastal supply boats and barges, isolating enemy-held islands from supply, reinforcement or evacuation
caption: A British World War II Vosper 73-ft. motor torpedo boat
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