The Arno XI is a hydroplane inspired by Achille Castoldi in the early 1950s and built by the Cantiere Timossi boatyard, located in Azzano (a frazione of Mezzegra) on the Lake Como. Castoldi wanted to establish a world water speed record so he persuaded then Ferrari racing drivers Alberto Ascari and Luigi Villoresi to influence Enzo Ferrari to supply him with a 4.5-litre, V12 Ferrari engine; the same engine that gave Ferrari his first Grand Prix victory with the Ferrari 375 F1 at Silverstone Circuit in 1951. The engine was installed in a Timossi three-point racing hydroplane hull.
In 1953 a new record was added on Lake Iseo, 150.19 mph. This record still stands for an 800 kg boat.
