A torpedo boat is a relatively small and fast naval ship designed to launch torpedoes at larger surface ships. They were created to counter the dreadnought and other large, slow and heavily armed ship by speed and agility.
During the late 1800s, the development of metal-hulled ships of large size, and the use of gyroscopes to even out the motion of waves, allowed for the rapid development of the very large gunship, which soon became known as dreadnoughts or battleships. These were fiendishly expensive, so only the largest and richest nations could afford to continue in the race to build such ships.
But at the same time, the new weight of armor slowed them, and the huge guns needed to penetrate that armor fired at very slow rates. This allowed for the possibility of a small and fast ship that could attack the battleships en-mass, at a much lower cost. However two problems remained, a weapon that could attack such a ship was not small, nor was a small power source available to power such a ship.
Both of these problems were solved at about the same time. The introduction of the steam turbine (and, later, the internal combustion engine) resulted in a power source that could offer much higher output from a small source. The introduction of the torpedo provided a weapon that could cripple, and sink, any battleship.
The result was the torpedo boat, a small boat perhaps 50 feet (15 m) in length with high speed, carrying a small number of torpedoes. They were inexpensive and could be purchased in quantity, allowing for mass attacks on larger fleets. While some of them would undoubtedly be lost to the guns of the larger ships while they ran into firing range, their cost was so low that sinking even one battleship in return would be a victory.
It is commonly acknowledged today that the very first torpedoboat was the Royal Norwegian Navy's HNoMS Rap—the name meaning 'fast'—ordered from Cheswick, England in 1873.
The introduction of the torpedo boat resulted in a flurry of activity in the fleets around the world, as smaller and faster guns were added to existing ships to ward off the new threat. Eventually an entirely new class of ships, the torpedo boat destroyer, was invented to counter them. These ships, today known simply as destroyers, were built with speed equal to the torpedo boats, but included light guns that could attack them before they were able to close on the main fleet. Considerable effort was put into designing fleet actions that would allow the destroyers to operate far enough from the main "van" to keep the torpedo boats away, while still remaining close enough that they couldn't be "picked off" by an opposing fleet.
Torpedo boats remained useful until World War II, in particular the Royal Navy (RN) Motor torpedo boats (MTBs), Kriegsmarine 'S-Booten' (Schnell-boot or fast-boat: British termed them E-boats) and US PT boats (standing for Patrol Torpedo) served their users well.
A classic fast toroedo boat boat action was the Channel Dash in February 1942 when German E-boats and destroyer defended the flotilla of Scharnhorst, Gneisenau, Prinz Eugen and several smaller ships againts RN MTBs.
By World War II torpedo boats were seriously hampered by the 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 change was the widespread arrival of patrol aircraft, which could hunt them down long before they could even see their targets.
The class has not entirely disappeared, due to the arrival of the guided missile. Today a number of navies operate boats of the same general size and concept as the older torpedo boats, but armed with long-range anti-shipping missiles that can be used at ranges between 30 and 70km. This reduces the need for high speed chases to a degree, and gives them much more room to operate in while approaching their targets. Aircraft remain a major threat, and any fleet combining air elements makes their use almost suicidal.
They are still used by many navys and cost guards to police their territorial waters against smugglers, particularly those smuggling narcotics and weapons to insurgents. The interdiction and boarding of potentialy armed hostile fast boats, which often are indistinguishable from legitimate coastal craft, is something which has to be done from a heavily armed fast boat, often with the assistance of maritime patrol aircraft.
- Bulgarian torpedo-boat Drzski (http://varna.info.bg/1912.htm) (bottom of page)
- Bulgarian torpedo-boat Drzski (http://www.pbase.com/ngruev/image/27633738)