One of the world’s most exclusive boats – a one-of-a-kind 1952 Ferrari-powered hydroplane – is up for auction, but you’ll need deep pockets if you’re tempted to curl your fingers around her helm, writes Lawrence Schaffler.

The immaculately-restored vessel – the Arno Xl – is soon to go under the hammer by auctioneer company DuPont Registry in Florida, USA, and she’s expected to draw plenty of international interest from well-heeled collectors. Her appeal stems not only from her unmistakable Ferrari lineage – or that she’s unique – but also because of her exotic, testosterone-fuelled history. That she was built at all is, in itself, an intriguing story.
It all began when one of Italy’s most famous speedboat racing legends of the post-war era – Achille Castoldi – thought he might like to have a crack at capturing the world speed record in the 800kg hydroplane class. Of course, he realised he needed help. He’d previously enlisted engines and design expertise from the likes of Alfa Romeo and Maserati – but this boat would need something special. So he approached Enzo Ferrari – the godfather of the world’s most famous motor-racing marque.

Enzo not only lent a sympathetic ear, he assigned a team of his best engineers to the project. They came up with the sleek machine you see in these images – constructed in steel and hard wood and covered in mahogany – and equipped it with aerodynamic features and stabilising fins.
Creating a suitably powerful engine to drive the hull proved a little more tricky. While Ferrari was a relative novice in the heady world of Formula 1 Grand Prix racing in 1952, its engines were already creating a stir. The engineers elected to use the same 4.5-litre, 12-cylinder engine built for the Ferrari 375 race car. Only four of these engines were ever built – three for the race cars, one for the hydroplane.
Even though the engine was a formidable beast, it only created 350hp. Castoldi knew he needed more – a lot more. Thus began an adventurous era of ‘firsts’ – the team decided to run the engine on methanol rather than conventional fuel. Two large magnetos were fitted to keep the engine running even if it was covered in water.
Each cylinder received two sparkplugs rather than the conventional one and, in pioneering go-fast add-ons, the team built two superchargers, two four-choke carburettors and a custom gearbox. These enhancements all added up to nearly 600hp. And just in case there was any confusion about the hydroplane’s DNA, she was finished in Ferrari’s signature red livery.
On October 15, 1953, at Italy’s Lake Iseo, Castoldi managed a two-way average speed of 150.19 mph, breaking the record by a healthy margin. It stands to this day. He later broke another record in the 24-nautical mile event.

Subsequent owners (there have been four) used the hydroplane in different ways. Owner #2 was Nando Dell’Orto – no relation, it seems, to the legendary Dell’Orto carburettor dynasty – who raced the boat until 1968, after which it sat in a warehouse for more than 25 years. In the 1990s, enthusiast Luciano Mombelli bought her and treated her to a full factory restoration at Ferrari’s classic car department – Ferrari Classiche. The fourth and current owner purchased the Arno Xl in 2012 – and is now selling her.
In addition to the famous vessel, the buyer gets a well-documented history file that includes hundreds of period photographs and handwritten notes from Ferrari’s engineers, attesting to her build and restoration. Among this is a copy of the Union Internationale Motonautique (UIM) certification detailing Castoldi’s 1953 speed record. UIM is the international governing body of powerboating, based in Monaco.
So much how would you be expected to part with to secure this beauty? DuPont Registry says the price is available upon request – but she’s widely expected to fetch around £1.5million ($2.87 million). Sotheby’s handled the auction in 2012, when the boat sold for €868,000 ($1.5 million).
For us lesser mortals, we will simply look from afar and dream.