British Coastal Defense Boat

  • World War II
  • 1 min

By Crusader1307

Although Military examples had existed prior to World War II as early as 1910 – The Thornycroft Marine Company developed a Class of Coastal Defense/Offense Boats used by The British Royal Navy. (12) were deployed off The Coast of England (in particular The English Channel), for the purposes of defending against a German Sea Invasion (seen as quite possible and even pending at one point). The Coastal Motors were on par with The US Navy's PT (Patrol Torpedo) Boats of The South Pacific Theater of World War II.


Crewed by between 3 and 5 Men, The Coastal Motor Boats were semi-enclosed and built to be as streamline (for speed) as possible. This included construction materials originally of wood (and later aluminum). Weight was all important. The Boat supported (2) 18-inch Torpedoes which were ''Deck Launched''. Their primary Mission was to engage German Troop Transport and Cargo Ships, draw in close and deploy their weapons. The proximity of the release of torpedoes made such duty highly dangerous.


A typical Coastal Boat was 60-feet long with a Beam of only 11-feet. The Class displaced 17-tons. Secondary munitions included the ability to deploy Surface Mines or Depth Charges and several varieties of Deck Mounted Machine Guns. Power was provided by a Single Thornycroft R12 6-cylinder Engine, which produced 650-HP (75-mph). While the planned Invasion of England via The Channel never came, The Boats were never used. The earlier Class in World War I did however see several engagements with The Imperial German Navy, with the loss of several Boats. (1) is known to have survived (restored) and is in a British Museum.