How alternative propulsion methods are transforming yachting layouts

There’s a natural tension between yacht engineers and interior designers. Both have the owner’s best interests at heart, yet both are also clamouring for more available space. 

Until recently, the technical format of a yacht has been pretty formulaic. The position and size of a superyacht engine room is dictated by the requirements of the main diesel engines, meaning it’s usually positioned aft of the lower deck. But as developments in alternative propulsion methods, from biofuel to methanol, continue to make leaps and bounds, builders, designers and naval architects are finding ways to leverage those changes to increase onboard guest comfort and revolutionise interior layouts.

Maximising living space on board 

Not only does an owner’s choice of propulsion affect speed, build cost and fuel burn, but it also now has an impact on the amount of available guest areas. One of the first examples was the 46-metre Wider 150. A hushed and compact diesel-electric propulsion system allowed Italian yard Wider to maximise the yacht’s spectacular living spaces designed by Ideaeitalia. With no traditional engine room to consider, the Wider 150 was conceived around the areas the owner loved rather than making spaces fit around a two-storey engine room layout.

“The beach club and the owner’s apartment were the ideas the project developed from,” affirms Alessio Battistini, co-founder of Ideaeitalia.

In 2019, yacht concept Aqua by Sinot Yacht Architecture & Design and Lateral Naval Architects introduced the world’s first hydrogen-electric system. Fitted with Lateral’s ‘Treadwater’ propulsion concept, it was a major step forward in showing how the application of new technologies aboard a 100m-plus superyacht can integrate a poetic design approach.

“We are firm believers in an evolutionary path of development and adaptation by learning,” says Sinot founder, Sander J. Sinot. “Merely repeating the same trick ad infinitum does not fit with our ambitions to constantly push for more advanced levels of design while extending the vocabulary and methodology of yacht building.”

Both Aqua and Lateral’s Mirage yacht concept, penned by Daroca Design, were early adopters of Lateral’s ‘Futurology’ concept. It focuses on innovative superyacht technical platforms that enable design via the application of engineering and technology. 

On Mirage, it manifests in a tweendeck engine room, which means the lower deck features four guest cabins and, rather unusually, the main salon. It provides guests with a breathtaking 270-degree view of the ocean. Full glass walls, connected by three sliding doors, let natural light fill the main salon, creating a bright and airy interior. On the main deck, a swimming pool serves as a beautiful focal point and enhances the overall design of the yacht.

“While every custom superyacht is unique, the technical backbone has evolved into a standardised solution,” says Adrien Thoumazeau, senior naval architect at Lateral Naval Architects. “We’re always looking to challenge ourselves and think outside the box in finding new ideas where the user experience could be elevated.”

The knock-on effect of compact engine rooms

Sanlorenzo’s 50Steel, which debuted at the Monaco Yacht Show in September and incorporates a hydrogen Fuel Cell system developed in collaboration with Siemens Energy, goes further still. The shipyard’s patented HER (Hidden Engine Room) allows for new ways of interpreting engine room layout while keeping the yacht under 500 tons of displacement.

Whereas traditional engine rooms occupy space on two decks, the 50Steel’s technical area is on the tank deck, with the lower deck dedicated to new guest spaces, including an additional lounge, which is directly connected on one side with the large aft beach club, and on the other side with the guest area, gym and spa.

“We have a duty to prove that we are trying our best and investing our money and our time to face sustainability challenges and try to find solutions,” explains Sanlorenzo CEO Massimo Perotti.

Also unveiled at Monaco this year was Feadship’s latest yacht concept C. The 75-metre design is defined by broad expanses of glass that draw light deep into its multi-level interior, turning the centre of circulation for owner and guests into a light-filled gallery. C also blurs the segregation of decks, staggering the fore and aft sections of each deck by a half-level amidships. Living and sleeping spaces are just a half-level from the next lifestyle area, be it up or down, and long corridors are banished.

Other design innovations include a partially enclosed lower deck sea lounge and waterfront dining area that extends when the side terraces are lowered, along with a gym and spa. This entire arrangement is made possible thanks to the yacht’s hull shape and fully electric propulsion system with inline contra rotating propellers.

The centreline propeller with azimuthing thruster allowed De Voogt’s naval architects to fashion a hull shape with an optimised, upswept aft body for less turbulence and a quieter wake. Both the centreline propeller and thruster are electric and draw power from an efficient DC electrical grid supplied entirely by fuel cells that run on methanol. The compact units reduce the space of the ‘engine’ compartment, meaning it easily fits on one deck.

“The smaller single-level engine room supported by the fuel cells maximises prime owner and guest space aboard, creating more value to an owner,” says Feadship’s senior designer Ruud Bakker.

It’s yet another example of how sustainable propulsion can work for both owner and planet.