Austin Marine Engines

In 1910 Herbert Austin decided to build a Marine engine that at the time was very advanced. It produce 300bhp and was installed in a speed-boat called "Irene I" which was named after his eldest daughter who had married Colonel Waite. The all aluminium twin ohv engine had twin magneto, twin carburettor and desmodronic valves. A year later in a revised boat now called "Irene II" and a new engine which produced 380 bhp. With this boat it successfully became the holder of the world water speed record on Southampton Water. (If anybody knows the actual speed, please contact me)

Irene Motor Boat
Irene at full throttle


Harmsworth Trophy

In 1903 the proprietor of the Daily Mail, Sir Alfred Harmsworth commissioned this bronze trophy to encourage the development of power boat racing. The contest would be between nations, and be run annually. Any nation could enter, but the boats had to be designed and built entirely by residents of that country, along with materials and engines etc. The first race ran took place on the 11th July 1903, which was won by S F Edge's in Napier Minor.

A wealthy Canadian financier, Sir Edgar Mackay, had three boats built to enter for the "The Harmsworth Trophy" bearing the name Maple Leaf I, II and III, but each boat had failed to come up to expectations.

Maple Leaf III had two huge Vl2 engines of about 350hp each, designed by the New Orleans Company but only constructed one, the second being constructed to the same design by Dixon Bros & Hutchinson Limited of Southampton. Mackay Edgar was not satisfied with Maple Leaf III's performance, so he decided to have the next boat, Maple Leaf IV constructed by S. E. Saunders of Cowes. Saunders had been involved in designing and building boats for many years, but they realised that though Maple Leaf III had powerful engines most of the power was absorbed by the friction of the water. It appears that various patents had been taken out whereby the underside of the boat varied in shape. Maple Leaf IV had an aquaplane hull having five steps of varying cross section, and at maximum speed would lift onto the third step.

Maple Leaf IV
Left to Right, Mr J W Kinchin - Lord Austin - Mr Stapleton, Engineer and Coxwain.

Mackay Edgar approached Austin were to improve the engines, and Mr J W Kinchin was given the task of improving the design of the American engines, working at Longbridge on their development. First he had the engines stripped down, and all components measured to see if they were correct to the drawings.

But one of the main problems was that the engines ran too hot, thereby causing various other components to fail. It soon became obvious, that if it was going to be competitive it would be necessary to implement a major redesign of the engine. New cast iron cylinders were designed that had much larger coolant passages. also the pistons were strengthened and lightened, along with changes to the valve train and the valves themselves.The side exhaust valves and overhead inlets were operated by push-rods from a single camshaft in the 'V' of the aluminium crankcase. This was driven by twin chains from the crankshaft, which ran on seven bearings. Each bank had its own magneto and carburettor.

To improve reliability a new pressure-fed oil system was designed that could supply all the bearings, etc, with a constant supply of oil at 20lbs per sq inch. Each block of six cylinders would have its own inlet manifold and exhaust system.

To start these large engines, a small ABC flat-twin engine was used.

By fitting new double-helical reducing gearboxes of Citroen design, the forward weight of the boat was reduced by a considerable amount.

Front End

Rear End

After carrying out various tests and modifications on the engines, it was now producing 380hp. But for the boat to stand any chance of regaining the record for England, it would have to reliably exceed 40 knots. With the testing at Longbridge over, it was now time to carry out testing on Southampton Water. It did three runs with the current and three against the current, averaging 45 knots on the Thorneycroft mile. With some more adjustments it finished the tests having now got the average speed up to 52 knots. Kinchin was very happy with the trials, and so he should be, because this was the first boat in the world to average over 50 knots.

It was now time to take the boat over to America, to aim at regaining the British international trophy from the Americans. The race took place in Huntington Bay, over a 30 mile course. The first race went to the American boat Reliance II, so it was must important that Maple Leaf IV with Tom Sopwith at the helm, wins the second race. All went well, with the Englishman crossing the line first. Now everything hinged on the last race, with Sopwith's seamanship and the boats constant performance in its favour. Maple Leaf IV crossed the line first in a time of 48 minutes 16 seconds, which was the fastest ever recorded at an average speed of 43.57mph. Second place went to the American Reliance III, coming in over three minutes later. Reliance II which won the first race failed to finish.

Maple Leaf IV

Boat information

Overall Length 40ft, - Beam 8' 5'', - Draught 3' 0", - Displacement 5.25 tons, - Engine 800hp,
Propeller Diameter 25", - Propeller speed 1,100rpm