The story of this electric ferry starts way back in 2013-2014 and goes through the BB Green 20m, a rigid monohull SES (Surface Effect Ship) designed for the ASV company to carry about 100 passengers. The patent then had corporate ups and downs that scuttled its implementation into production, thus limiting it to the production of the electrically powered sailing prototype.
In this project, there was a desire on the part of the main initiator, Fredrik Thornell (current executive director and founder of Green City Ferries), to create a particularly energy-efficient high-speed passenger vessel.
STATE-OF-THE-ART FOIL-ASSISTED CATAMARAN
Thus, having abandoned the SES hull project, Thornell contacted Nic de Waal, CEO of Teknicraft, to develop a next-generation foil-assisted catamaran that had a much larger range of applications and other advantages compared to the monohull of BB Green.
This type of hull – similar to SES, albeit with different principles – has a low-resistance type of navigation. The previous BB Green project had already involved the firm of Architect Mauro Sculli, so when Green City Ferries decided to start designing a new vessel for the same purpose, Sculli was again included in the technical team with the assignment for exterior design, general layout, and interior design.
Thornell emphasizes: “The objective of GCF was to reinvent sustainable marine transport, not only by making it emission free, but also by making it attractive by combining beautiful yacht design from Italy with efficient and comfortable hull design from New Zealand.“
THE FIRST STEPS AT A DISTANCE
This project was born during the Covid-19 period, and due to the material impossibility of traveling, most of the project meetings among team members took place remotely.
Sculli says: “We had weekly remote briefings every Tuesday with New Zealand studio Teknicraft and other team members. In fact, I physically met only Thornell. The only in-person meetings were those done for the issuance of ISO certifications with DNV – Det Norske Veritas [classification society founded in Oslo for the maritime sector, NDR]. Basically, the three physical poles of this project were Sweden, Italy, and New Zealand. Despite this logistical complication, the modus operandi was very effective.”
Exterior design
Parallel to the technical choices, the style of the project has also changed and evolved, in part due to foils, in a rather futuristic direction. The “streamlined” exterior styling of the new vessel, with its highly connected curved lines, may recall that of an aircraft, with particular reference to the longitudinal profile and center console, with the wheelhouse resembling the nose of an airliner.
Another hallmark of the exteriors is the continuous dark side windows that follow and emphasize the curves of the profile and give a dynamic sense to the boat even when moored at the dock. The superstructures of the catamaran’s side hulls (which already rise from the forward ends) and the central one of the wheelhouse cabin create two paths, one to port and one to starboard, for passengers to enter from the bow at each stop of the boat.
There are large photovoltaic surfaces on the roof that are perfectly consistent with the choice of electric propulsion. In the variant that takes advantage of hydrogen-powered boat technology, however, a series of cylinders for storing the hydrogen itself is proudly displayed.
Layout and interior design
The vessel is designed to comfortably accommodate up to 147 passengers and up to 28 bicycles, fully embracing green intermodality. The goal was the convenience of access from the bow and stern, although, in ordinary use, passenger embarkation and disembarkation are expected via a forward gangway. The dedicated space for carrying bicycles (very common in Northern Europe) is on the sides of the forward entrance so as to avoid excessive movement and difficult maneuvering.
Upon entering the interior, passengers can sit for the duration of their journey. In the absence of rain, there is the possibility for a number of them to stay outside in the aft area. All developable paths on the boat have been made accessible for everybody, wide enough to allow the exchange of a walking person and a wheelchair user. In line with this need, one of the two bathrooms available on board has measurements and sanitary fittings that make it fully accessible.
The interior design is quite understated but elegant, the colors are light, and the rooms are designed to be bright.
A peculiar catamaran
The boat’s carbon fiber hull has special features that make it extremely energy efficient. Between the hulls of the catamaran, about midship, a foil is installed that, while not developing true flight, reduces displacement by up to 40 to 50%. The boat, thus lightened and with less wetted surface, produces much less drag; consequently, it can increase its cruising speed while consuming less and also improving its range.
The foil structure is fixed and does not require adjustment; this simplifies navigation and maintenance and reduces any technical problems. The hull has no real rudders, but great maneuverability is provided by the waterjets.
From an environmental impact point of view, a boat that reduces its displacement by so much when sailing also produces the not negligible advantage of creating waves no higher than 25 cm.
Nic De Waal explains how his team worked to carry out the necessary verifications while fine-tuning the hull shapes: “We stopped using naval tank testing some years ago when it became clear that CFD is more accurate in predicting calm water resistance than a scale model in a tank. Significant CFD was used for the design of Beluga24. Teknicraft’s experience with many other foil-supported designs enabled us to compare and validate the CFD results with our other designs in operation.”
Variants and current status of the project
A variant of the vessel has also been developed for passenger transport in the Greek islands. In this case, a slightly higher loadline has been provided to safely deal with a slightly rougher sea than is normally found in the fjords or the New York Bay. Additional layouts have already been developed and adapted for Arab countries, with more luxurious interiors for 40-50 passengers and with halls and lounges for different uses.
Near future: hydrogen and fuel cell propulsion
As an alternative to the basic version with electric propulsion, a hydrogen-powered boat version is being developed, using fuel cells in place of batteries to power the electric motor.
Special hydrogen cylinders, capable of withstanding very high pressures, will be placed on the roof of the vessel. At room temperature and pressure, in fact, hydrogen is in gas form and has an extremely low density: storage in gaseous form of a significant amount of hydrogen requires cylinders capable of withstanding very high pressures, around 10,000-12,000 psi.
Comparing the weights produced by battery pack versions on the one hand, and hydrogen/fuel cell versions on the other, Nic De Waal says: “We don’t think there is a major difference in weight between the 2 solutions. However, when the weight of the two systems is approximately even, the hydrogen version will have up to 5 times more range.”
With its headquarters located in the old part of Stockholm in Sweden. GCF has the ambition to sell 150 vessels within the next ten years. Traditionally, the shipyard industry has built vessels to customers’ orders, and thus, there are almost no economies of scale. As the emission-free high-speed ferry market is in its infancy, there are possibilities to set new rules. Established by: Hans & Fredrik Thornell Executive Team: Hans Thornell, chairman and founder Fredrik Thornell, executive director and founder David King, CEO Björn Gunnerholm, business development John Carroll, GCF Inc Americas Tech Team: Anders Lönnö, head of Composite Niclas Kling, head of ship design Nic de Waal, CEO Teknicraft Andy Kensington, director Pure Design Mauro Sculli, CEO Sculli Design Studios Ulf Brändström, founder of Vaxholm Komposit.
