PHI

• LOA 58.5 m, 499 GT
• Van Oossanen XL Fast Displacement Hull Form
• Exterior by Cor D. Rover, interior by Lawson Robb
• Top speed 22 knots, over 20 knots on trials
• Aluminium hull and superstructure
• Patented freshwater-saving pool, gyro stabilisation
• 12 guests, 11 crew
• Delivered December 2021

Why a sailing yard built her

When Royal Huisman announced a 58.5 metre motoryacht, the industry paid attention, because the yard's obsessions transfer. Sixty years of aluminium construction and race-bred weight discipline are exactly what a long, light, efficient motoryacht needs. PHI was the demonstration, a full custom project that took the standards of the sailing fleet, paint, joinery, systems engineering, and pointed them at a different kind of owner.

The result claimed a record on arrival. Trade press reported PHI as the longest motoryacht in the world under 500 gross tons, a title that is really a compliment to her naval architects and builders. Stretching maximum length under the regulatory volume line takes obsessive structural efficiency, and obsessive structural efficiency is the family business in Vollenhove.

The hull does the work

Van Oossanen Naval Architects gave PHI its XL Fast Displacement Hull Form, the Dutch firm's signature shape that erases the usual wall between displacement comfort and planing speed. She recorded over 20 knots on sea trials and tops out around 22, yet at passage speeds the slender hull slips along with the fuel appetite of a much smaller yacht.

Cor D. Rover's exterior makes the engineering visible. PHI is long, low and glassy, named for the Greek letter of the golden ratio, and her proportions were drawn to honour it. There is no wedding-cake stacking of decks, just an unbroken line that reads at anchor like a piece of consumer product design scaled to 58 metres.

PHI was reported at delivery as the longest motoryacht in the world under 500 gross tons, built by a yard famous for sail.

Inside the glass

London studio Lawson Robb shaped the interior for twelve guests with eleven crew, and organised it in an unusual way, the upper deck is given to what the yard describes as a penthouse apartment, while the main deck serves shared daytime life. It is a city-living logic transplanted afloat, and it gives the owner a private domain with the best views on board.

The detailing runs deep. A patented pool with a flush cover converts to a sealed tank to conserve fresh water underway. The lower deck carries what the project team called an infinite wine cellar. Gyro stabilisation keeps the slender hull calm at anchor. None of it is flash for its own sake, each device solves a real problem of life aboard.

Built like a Huisman

PHI is aluminium throughout, hull and superstructure, built to the same standard as the sailing fleet and finished to the same paint tolerances. For a motoryacht owner the material argument is the same one sailors have enjoyed for decades, a structure that shrugs off fatigue, welds instead of delaminating, and gives surveyors nothing to guess about at resale time.

She was also proof of concept for the yard's motoryacht ambitions, delivered on the heels of her launch in July 2021 and handed over that December after North Sea trials. The build showed that Vollenhove's project management scales beyond sail, and the order book since, including the world's largest sportfish yacht, suggests the market drew the same conclusion.

The owner's calculus

The sub-500 GT class is the sweet spot of modern yachting, large enough for twelve guests in genuine luxury, small enough to avoid the heavier compliance regime above the line. PHI holds the extreme end of that class, maximum waterline, maximum presence, minimum regulatory drag, wrapped in a design that will not date.

For buyers comparing the established Dutch motoryacht houses, PHI adds a new name to the shortlist with an old reputation attached. She carries the build quality the sailing world has priced at a premium for decades, applied to a hull form the fast displacement specialists consider the state of the art. That combination did not exist before 2021.

Who it is for: The owner who wants maximum length and pace under the 500 GT line, with Dutch sailing-yacht build quality in a motoryacht.