Even though RM Auctions is most-known for their impressive array of cars up for bid, sometimes an unusual item appears in the lot. On May 11th and 12th, an impressive Ferrari speedboat built between 1952 and 1953 will be up for auction where it is expected to fetch between $1.3 million and $1.9 million. It’s not just a Ferrari-turned-boat on the water, but a truly one-of-a-kind racer, built personally for boat-racing privateer Achille Castoldi.

The 1953 Timossi-Ferrari Arno XI Racing Hydroplane was Castoldi’s famed racing hydroplane. Arno XI set the world speed record in its class on October 15 1953 at 241.708 km (150.19 mph). Amazingly, the record still stands today. Although it changed ownership three times in its lifetime, the boat was painstakingly but beautifully restored in 1993 and its engine was confirmed as original by Ferrari S.p.A.

Castoldi was the brainchild behind the making of the boat. He called on his friend Ferrari Grand Prix drivers Alberto Ascari and Luigi Villoresi to convince Enzo Ferrari to provide the knowledge and technical assistance to develop the boat. That resulted in horsepower provided by a 12-cylinder, 4,500 cc V12 Ferrari engine, the same as that installed 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, with the only addition being twin superchargers that developed in excess of 502bhp at 6000rpm, according to a previous press release.

Other notable items at the auction this spring include a pair of Riva boats, Ducati motorcycles including the SBK Corsa, 1956 175 Sport, 1961 125 TV “Testone”, and famed cars like a 1968 Alfa Romeo, a 1956 Porsche Carrera, and a 1971 Ferrari Daytona Spyder.

Photos courtesy of RM Auctions