Designed in 1909 by Sir John Thornycroft for his own use and built by Hart-Harden on the Thames, Miranda IV was launched in 1910 and is generally considered to be the world's first hydroplane. Developed from earlier models, the Miranda IV was fitted with an aquaplane under her bow so that as the four-cylinder 110 horse-power Thornycroft engine's throttle was opened, the forward plane rose clear of the water. Despite measuring 26 feet with a 6 foot beam and weighing nearly a ton, it was one of the fastest boats of its time achieving speeds of around 35 knots on its trials. Constructed from mahogany bottom planking with pine sides, the Miranda IV was painted in British racing green with a white underbody and deck. Her sister boat Zigarella, although laid down to same design, was less successful possibly due to problems in the forward positioning of circulation system which was further back on the Miranda IV. Unlike many other racing boats the Miranda IV kept remarkably dry so she did not require an oil skin lining as spray was rarely thrown over the side of the boat. She won twice at the Bournemouth Regatta (July 18^th--20^th, 1910) and again at the annual Motor Yacht Club Regatta in Southampton (July 30^th--August 1^st, 1910) covering sixteen miles in under 33 minutes. Miranda IV is still in existence and on display in Old Tailem Town Museum in South Australia.