With its just-launched 50-metre boat Home (formerly Project NOVA), Heesen has become the first shipyard to offer 'silent cruising' mode on an FDHF (Fast-Displacement Hull Form) motor yacht.
We've done this by experimenting with hybrid propulsion. Hybrid boats typically operate using two distinct energy sources: traditional propulsion using an engine, gearbox and propeller shaft, and then a separate electric motor which is powered by generators. This allows for the possibility of running on diesel mechanical, diesel electric, or both.
On a typical boat, diesel engines and thrusting propellers make a good amount of noise and vibration, but when you sail Home in the diesel electric mode, the main engine shuts down and you only have the generator quietly running. To further reduce audibility, we've located the generators on flexible mounts inside an enclosed sound-box.
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Running on electric, Home's noise level is as quiet as when it's anchored in dock at harbour. Typically this is just 46 decibels – about the pitch of gently pattering rain. As for velocity, the electrical mode allows for speeds of up to nine knots – with 60 knots possible in diesel mechanical mode.
Why did we pursue silent cruising? Well, the industry trend has long been towards green technology, and Heesen has been at the forefront of this for years: its lightweight-aluminium high-speed vessels are always ultra-efficient. But since eco-friendliness is now the norm, we thought to ourselves: how else can we innovate with hybrid propulsion? What other luxuries do our clients want?
We asked Professor Barry C Smith, founder of the Centre for the Study of the Senses, how dining is affected by silence? His research is fascinating: it shows that the tongue’s ability to detect flavours can be much reduced during periods of palpable noise.
Normally during sailing, you anchor somewhere for a swim and then eat later at night, when the boat is noisily sailing again. This gives Home a huge advantage because aboard her one can take that dinner cruise after dark in silent-cruising mode, and therefore enjoy food and drink to the full. The silent mode also allows Home's captain to start early and leave port without waking his or her owners or guests.
Silence is far from the boat's only luxury, though. For Home's exterior lines, we enlisted Frank Laupman at Omega Architects – a fellow Dutch company with whom we've worked for years – to create a kind of beach house on the sea. Features include a gin bar connected to the large swim platform, a white and classily-modern aesthetic, and a permanent sense of being right beside the sea.
Further inside, interiors shaped by Cristiano Gatto Design of Italy keep the boat clean and minimal, with big windows and not too much furniture or clutter. This simplicity complements the offering of silent cruising.
I think that the next generation of superyachts will gradually move towards hydrogen fuel cells, like those we already see in battery-powered cars like the Toyota Prius. With its silent-cruising mode, Home is a pioneering step in this prevailing direction.
PETER VAN DER ZANDEN is the general manager of design and development at Heesen Yachts, an award-winning specialist in custom-built superyachts; heesenyachts.com
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