Onboard experiences of the new hybrid propulsion and energy system


Onboard experiences of the new hybrid propulsion and energy system

The decision to modernise Foftein, a 30m / 99ft Royal Huisman cutter (1999) with a 20-year-old propulsion and energy system was rooted in several fundamental considerations. Her captain Tim Jones explains all about his experiences with the new setup and tells of the benefits for her owner and all onboard.

Foftein (Royal Huisman, 1999)


We are setting the standard!

“Showing what could be achieved was the foundation on which the system was designed. It was essential for us to show that a 20-year-old yacht could be transformed into a state of the art superyacht that is ready to sail into a greener future. We are setting the standard! The additional design and installation challenges confronted in such a project required a lot of planning and investigation with the Royal Huisman team and engineers. 


Planning for the future is arguable one of the most essential aspects of a successful business or life. We took this point of view seriously and designed a solid and reliable system with high quality, long-lasting components and the ability to be improved easily as the battery technology improves in the coming years, allowing for longer silent times and more silent miles.

Foftein post-Huisfit: the centerpiece of her hybrid conversion is a new gearbox, aligned with a sophisticated new electric motor/generator



Simplification was a critical design brief for us. We wanted a highly automated system with a simple interface that allows the yacht to automatically manage the energy demands with minimal input or monitoring from the crew or owner. Royal Huisman has delivered a sleek and easy to operate system that minimises time, and maximises efficiency.


Backup systems and redundancy are essential in a global travelling yacht such as Foftein. There was no option to have two generators or two main engines with her modest-sized engine room and available space. With the hybrid energy system, we have mitigated these drawbacks by designing the system in such a way that it has double redundancy on almost every critical system. Main engine failure can be covered by the permanent magnet motor unit on the driveline, either running in full electric mode at 8 knots, or extending the range by running the variable speed generator in diesel-electric mode, offering days of non-stop cruising.

Running the main engine in diesel / generator mode provides us with the benefit of not having to run a separate generator to charge the two 700V lithium battery banks while covering the vessel’s hotel loads. We do this all at maximum efficiency with no wasted fuel, energy or adding run hours on the generator, reducing service intervals and maintenance costs.

AC blackout or dead ship is a situation no yacht crew wants to find themselves in. An automated system heavily reliant on programmable logic controllers (PLC) and programming may sound counterintuitive when speaking about redundancy. Superyacht crew all know PLC’s can sometimes refuse to corporate. Royal Huisman has delivered a system with well-layered emergency operation and recovery procedures that are easy to follow and quick to implement in the unlikely event of a PLC failure. We can run every system manually without PLC control. This was a key aspect and an essential layer in the system’s support and operation.


The importance of this system requirement could not be overlooked or compromised on in any way, whether it’s having the ability to regenerate power while sailing, or recovering heat from the engines and air-conditioning to provide hot water. We are utilising a frequency driven raw water system that adjusts pressure and flow when individual systems require it. As the world transitions to a more sustainable future, it’s our responsibility to push the boundaries and possibilities with energy efficiency.


Providing a silent experience for the owner was made easier by building off the earlier foundations and requirements. Giving the owner a silent night while still enjoying all the comforts of an air-conditioned cabin is a game-changer for the quality of time and experience onboard. No longer do we have to put up with the constant noise and fumes of a generator running at minimal load or efficiency to provide the needed power. 1.5 Hours of generator charging can give us up to 8 hours of silent time, providing a truly unique experience onboard. The fast charge time can allow the crew to take advantage of running the generator when the owner is out paddle-boarding or taking a walk, improving the silent time dramatically.  The experience and enjoyment when Foftein silently departs the dock are unmistakable. Having the ability to depart the harbour under silent electric mode, hoist sails silently, then sail over the horizon while regenerating power, is an experience like no other.

Updated helm controls post-Huisfit (click on the photos to see more)



It was essential that Foftein’s transition to a hybrid-electric propulsion system was done in a style in keeping with the yacht’s prestige and class. Therefore, maintaining the classic and minimal helm station was a crucial point in the system brief. This was achieved by the simple, minimal, well-designed helm controls that merge seamlessly with the yacht’s existing appearance. To the unsuspecting eye, Foftein is still a beautiful classic looking yacht – but with a state-of-the-art hybrid electric system hiding beneath her signature Germán Frers lines and varnished cherry interior.”

Are you sailing a superyacht with 20th century technology?

And keen to embrace all the latest hybrid technology benefits?

A conversion by Royal Huisman’s Huisfit from conventional into hybrid is the ultimate systems upgrade: see and learn more at [click here]

Foftein – Cutter rigged sailing yacht – naval architect: Germán Frers – interior decorator: Pieter Beeldsnijder – length including bowsprit: 33m / 108ft – length hull: 30m / 99ft – builder: Royal Huisman (1999) – [click here]

“Huisfit is offering a number of smart green solutions to reduce the use of energy onboard superyachts with 20th century technology. A conversion by Huisfit in Amsterdam – from conventional to hybrid – is the ultimate systems upgrade with leading-edge propulsion and power generation”

Juliet re-launched following hybrid conversion by Huisfit

Amsterdam, June 2021 – The 44m / 143ft Royal Huisman world cruising ketch was launched in 1993 and is a fine example of pioneering, custom-built technologies in late 20th century yacht building. With nearly a quarter million of ocean miles under her keel, she still looks and sails like a dream. Juliet returned to Royal Huisman for Huisfit, the shipyard’s refit services, in Amsterdam, to “go green” and become future-proof, by embracing all the latest hybrid technology benefits.

Juliet’s re-launch just before the summer of 2021 marks a noteworthy step closer to delivery. Soon, her owners can enjoy the exceptional lifestyle and environmental benefits of hybrid sailing, including silent operation, zero emissions, peak-shaving, shaft-generated power under sail and reduced fuel consumption, combined with enhanced operational flexibility and redundancy.

Read the news and background information on this website followed by the links to News > Inhuis Stories & Updates [click here]

Under sail, electrical power will be generated by the propeller’s rotation – answering every sailor’s dream to hoist the sails, capture the wind and silence ‘that noisy and smelly engine’

HUISFIT  –  Superyacht Refit, Rebuild and Renewal by Royal Huisman

Huisfit, has enjoyed growing success since extending its reach to the wider superyacht fleet. Huisfit offers everything from classification-driven refit and maintenance work to the re-arrangement and refurbishment of superyacht interiors. In recent years Huisfit has proven to be a specialist for various yacht conversions, rebuilds and “green” solutions for both motor- and sailing yachts.

The Huisfit team recognizes that every refit comes with a unique set of requirements, relevant infrastructure, access to specialist trade skills and equipment, and suitable slots to respect the yacht’s schedule: expertise à la carte. All projects are able to benefit from the comprehensive and highly regarded in-house design engineering capability of Royal Huisman and sistercompany Rondal.

Located in the heart of the Dutch maritime services cluster, Royal Huisman’s dedicated refit division can accommodate any yacht. Huisfit has already proven itself to superyachts built by shipyards like Feadship, Lürssen, Abeking & Rasmussen, Heesen, Claasen, Holland Jachtbouw. In addition numerous Royal Huisman-built yachts have benefitted from Huisfit over the last decades. More information: [click here]

Sailing yacht Adèle returns

Huisfit is pleased to announce that the Owner of the 55m / 180ft classic ketch Adèle (Vitters, 2005) appointed Huisfit for excessive refit and service work including her 15 year survey later this year. Previously she received a successful refit and class survey in 2016 at Huisfit, the foundation was laid for a long term relation with the great team of S/Y Adèle.

And why Huisfit again? Project manager Taco Zwarts, who is representing the Owners explains their decision to return in 2021: “After the previous successful refit by Huisfit, it was clear and very obvious for us. In a nutshell: The Huisfit team is honest and the cooperation is smooth; the technical updates were well executed and of high quality […] Also, since that moment the shipyard’s service team supported us worldwide whenever needed.”