President John F. Kennedy had numerous brushes with death before an assassin’s bullet ended his life 50 years ago today. Sickly throughout a childhood he wasn’t expected to survive, JFK had to leverage his family’s considerable political influence just to “pass” his Navy physical. And while serving in the South Pacific during World War II he once again narrowly escaped death aboard the most effective fast attack craft of the era: the Patrol Torpedo boat.
PT Boats, or just PT’s (or “Devil Boats” by the Japanese), were originally conceived as fast-moving anti-aircraft platforms however they proved massively effective at surface engagement as well. Operating throughout the whole of the Pacific Theatre, their small size, fast speed and high manoeuvrability allowed these boats to employ hit-and-run tactics, quickly closing in on their targets and unleashing up to four torpedoes before high-tailing it out of there. They often operated under the cover of darkness to reduce the chances of being spotted outside of torpedo range. No enemy ship — from the armoured barges that ferried Japanese troops between islands to full-size Destroyers — was safe from the PT “Mosquito fleet”. Additionally, PT’s turned out to be quite useful at laying mines, performing raids, setting smoke screens, SAR operations and light ISR missions.
Developed by the Navy beginning in 1939, PT’s slowly evolved over the course of the war into three sub-types; the largest one being the PT-103 built by the Elco company’s naval division. At 24m with a 6m beam and tipping the scales at 50 tonnes, the PT-103 division were far smaller, lighter, and faster than the hulking 300-ton “fast” attack craft employed in the Great War.
Much of this weight savings came from the ship’s wooden construction. Much like today’s Avenger-class mine-hunters, PT’s were built of inch-thick mahogany planks layered around glue-impregnated canvas and held together with bronze screws and copper rivets. Its solid and sturdy construction allowed even extensive hull damage to easily be repaired on the front lines. Heck even PT-109, JFK’s command, remained afloat for half a day and it had been cut in cleanly in two by collision with a Japanese Destroyer.
PT’s were propelled by a trio of modified V-12 liquid-cooled aircraft engines based on those found in the WWI Huff-Daland XB-1 Liberty bomber. While they generated enough horsepower for a 50-knot top speed, they also drank 100 octane gas like it was going out of style. The PT’s 11,000-litre supply lasted, at most, 12 hours — 250 litres per engine per hour. At speeds above 41 knots, a PT boat could guzzle a tank in half that time.
The weapon of choice for these boats was originally the 1180kg Mark 8 torpedo. Its 207kg TNT-packed warhead could blow holes in even reinforced hulls from up to 15km away. The system was upgraded in 1943 to utilise the larger Mark 13’s which packed 270kg of Torpex-filled warhead. Topside, PT boats bristled with automatic weapons: a pair of twin M2 .50-cal’s as well as a 20mm Oerlikon cannon. PT’s patrolling the front lines were also routinely outfitted with mission-specific hardware like anti-aircraft guns, depth charges and sub-sea mines.
Though they served valiantly throughout the Second World War, the Mosquito Fleet was dismantled shortly after VJ-Day. Just one PT-103 has survived to today: PT 617, which still resides in Battleship Cove, Fall River, Massachusetts. [US Navy – Wiki – PT King – PT Boats]
Pictures: National Archives