ref no. 18S/1; type T5AM/1; contract no. 6MC/766; serial no. 59.

Designed to be installed in aluminium lifeboats, parachute-dropped to downed aircrews bobbing in the Pacific Ocean.

Like so many other companies, Vincent ceased motorcycle production in 1939 and the factory shifted their efforts over to the war effort, mainly the manufacture of munitions. But in 1942 the Royal Air Force, expecting a protracted campaign against the Japanese, was looking for a lightweight, highly efficient lifeboat engine that could run reliably for extended periods of time.

Company boss Phil Vincent already held patents on a suitable design, which he turned over to Phil Irving for final engineering. The result was a 500cc opposed-cylinder design with three bores each containing two pistons. The outer two cylinders produced power, while the middle cylinder with double acting pistons fed the other two. Unfortunately, this unique engine program wasn't completed before the end of hostilities, though in final form the motor seemed to meet all of its design goals. Producing 15bhp at 3,000rpm, with 50 gallons of fuel on board, the Vincent two-stroke should have been good for up to 5 knots per hour, which certainly beats swimming or fighting off sharks. The government contracted an order of five Vincent HRD Marine engines, after negotiations the Air Ministry increased the order from five to twelve. It is believed that this example is one of twelve to survive.

This particular engine was kept under a sheet in the garden for the past 25 years and was intended to be used in a canal boat before it was purchased by the current vendor. Following a long period of inactivity, restoration to a greater or lesser extent is recommended therefore, close inspection is advised. Prospective bidders must satisfy themselves as to the completeness, condition and suitability of the lot prior to bidding. Offered with sundry spares.