Developed by Achille Castoldi, who – thanks to his friendship with Alberto Ascari and Luigi Villoresi – was able to call upon Ferrari for assistance, the ARNO XI is powered by the same 12-cylinder, 4,500cc V12 Ferrari engine as that in the Type 375 Grand Prix car that gave José Froilán González Ferrari’s first ever World Championship Grand Prix Victory at Silverstone in 1951. The only additions were twin superchargers that boost power to a remarkable 502bhp at 6000rpm.

On 15th October 1953, the ARNO XI set a world speed record for an 800kg boat on Lake Iseo in northern Italy. Amazingly, this record (150.19mph) still stands today. The boat also had an extensive and successful racing history right through to 1960, having undergone various aerodynamic improvements in period, including a modified nose and the addition of a fin.

“It has that alluring mix of 50s Ferrari Grand Prix car and the sheer beauty and simplicity of the hydroplanes of the period,” says RM’s Peter Wallman. With just three owners from new, and a continuous, well-documented history, the ARNO XI carries an estimate of 1m to 1.5m euros.

 
Photos: RM Auctions