For 1953, Castoldi decided to focus on setting top speed records. He commissioned an 800kg-class three-point hydroplane hull to be built by Cantieri Timossi, a hydroplane builder on Lake Como, near Milan… The hull was dubbed Arno XI. For the engine, he turned to the new up and comers of the auto racing scene – Scuderia Ferrari… On the morning of October 15, 1953, Achille Castoldi succeeded in smashing the 800kg class speed record with an average ''flying kilometer'' two-way speed of 150.49 mph. He followed up the performance later that day by setting another record in the ''24 nautical miles'' event with an average speed of 102.34 mph… Arno XI was restored in the early 1990s and was put up for auction at the Coy's Festival at Silverstone in 1997 where it did not sell. It was photographed skimming across the water as recently as September 2004, along with many other vintage racing boats...
