Chantiers de l’Atlantique discusses its wind propulsion cruise design and the construction of LNG-powered vessels
Chantiers de l’Atlantique is seeking to become a leader in alternative power use in passenger shipping, with orders for LNG-powered cruise ships on its books, a patented LNG and bunkering design and the trialling of its wind propulsion cruise design.
The company has been refining its Silenseas concept, which uses wind propulsion. Vice president of projects and ship performance Stéphane Cordier says: “We have achieved our goal in that we have narrowed down the application already to a 200 m, 300-passenger ship. We have been developing sails and masts which are well suited for that ship size.”
Silenseas uses the company’s self-developed technology called Solid Sail to draw on wind power. The sails are mounted on masts. There are three rigs, and the masts rotate to adapt the sails to the wind. The shipyard expects the wind propulsion to be combined with other sources of energy, such as LNG or fuel cells.
A prototype of the sail technology – a 250 m² sail – was fitted in Q4 last year on Le Ponant cruise ship. Two patents have been filed by the shipyard, in 2009 and 2017, for a new type of sail made of fibreglass, carbon and epoxy-resin panels in a carbon-slat frame.
Mr Cordier says: “Le Ponant has crossed the Atlantic and been in the Caribbean, and [its vessel owner] Ponant is very happy with it. It is a very flat sail so they can manage it in different conditions without having it shake and flutter. Also, its aerodynamic performance has been measured to be at least as good as the conventional canvas sails it replaces. We are discussing with Ponant the possibility of refitting the three mainsails with Solid Sails.”
The shipyard has also estimated that at least 30% is saved on propulsion power, based on simulations of an itinerary that does not change according to wind conditions, leading to a 15% gain on the total energy bill. Mr Cordier adds: “This of course depends on the wind and geographic situation, but there is also the potential if the route is adapted to the weather situation that it can be much more.”
Elsewhere, the shipyard has been busy producing the MSC Meraviglia-class cruise ship. It is currently working on the MSC Grandiosa; the third in class. This is a stretched version of MSC Meraviglia and MSC Bellissima, being 16 m longer. Mr Cordier explains: “After you deliver the prototype ship and the second one, you get a very good idea of what the potential of the ship is in terms of possible growth and how it is actually working in terms of restaurants and elevators and all operational matters, and whether the ship is performing well enough to support additional passengers.”
The longer ship can accommodate 156 more cabins and up to 270 more passengers, while only raising the tonnage to 177,000 gt from 171,000 gt.
Mr Cordier comments: “This is a classic stretch, inserting a new segment of the ship in the middle, and comparable to a stretch on an existing ship [jumboisation], where you integrate a slice in the existing fire zones and it is a rather straightforward modification, as opposed to other stretches where different fire zones are stretched, which has been done on other ships.”
MSC Grandiosa was delivered at the end of October.
The most significant development in the Meraviglia-class is that the fifth ship to be built will use LNG as fuel – a departure from the first four vessels, which are equipped with scrubbers (see below). The fifth will be based on the same stretched design as MSC Grandiosa.
Mr Cordier explains: “That involved a total redesign of the lower part of the ship to accommodate the tanks. It worked well with the stretched version, although we have had to relocate some of the crew space. The challenge has been in terms of space.”
Four Wärtsilä dual-fuel engines have been selected. “It means fitting a different model [but] on the propulsion side nothing else has changed.”
This will be the second LNG-powered ship that Chantiers de l’Atlantique is building for MSC Cruises. Its first order was for the dual-fuelled first ship in the World class, of which Mr Cordier says: “Ground-breaking work has been done for the World-class ship, so we are drawing on a lot of that experience.”
The first World-class cruise ship is set to be delivered in 2022. “We have a detailed design on the way and all equipment is selected. It is well underway,” says Mr Cordier. The vessels will have a gross tonnage of 206,000 and 2,600 cabins.
The five dual-fuel engines will deliver 80 MW of power, with the propulsion through two shaft lines as opposed to pods, as the unit power for the two-propeller drive is above the current limitation of the pods.
The shipyard has extensive experience in LNG. As well as designing and constructing LNG tankers, it has also designed an LNG-powered ferry for Brittany Ferries, which is being built by Flensburger shipyard in Germany. Chantiers was unable to build it for the desired delivery date because it did not have the capacity, so a licensing agreement was developed allowing Flensburger to construct the vessel based on Chantiers de l’Atlantique’s design.
One of the key features of the ferry design is the bunkering truck feeder concept that the shipyard has patented. This involves a buffer tank being installed on board. LNG trucks come on deck and connect to the buffer tank, which then feeds the engines. Mr Cordier points out the benefits of the system, including time saving and ease of use: “The LNG trucks are loaded like other trucks onto a special designated space on the ship and hooked to the LNG system. Our system avoids the bunkering part where you would have trucks alongside filling tanks in the ship. Tanks in the ship take a lot of space and the operation takes time. It is also a risky operation in harbours, and there other safety considerations.”
He believes that such a system would be suited to using alternative fuels such as hydrogen. “There is the potential to use hydrogen on short routes and daily turnaround ports with fuel cells.”
Meraviglia-class: swapping scrubbers for LNG
When MSC Cruises initially designed its Meraviglia-class ships in 2013, there were still a lot of technical and infrastructure constraints around LNG as a fuel option for cruise ships.
As the company explains, when it placed the order for four Meraviglia-class ships with Chantiers de l’Atlantique, they were not planned to run on LNG. But following progress in this area over the ensuing years, the company decided to investigate the option of fuelling their next vessel with LNG.
In 2015 the cruise operator designed its future World-class specifically to run on LNG.
An MSC Cruises spokesperson explains: “As we made progress in this space, we started exploring the possibility to equip ships within the same Meraviglia-class with LNG. We faced some considerable challenges, as LNG tanks take more than double the space of standard fuel tanks. It would require a fundamental redesign of the ship’s interior spaces, affecting both crew and passenger areas.
“Despite the challenges, we worked hard to develop a plan for our fifth ship in the Meraviglia-class, an additional order that we placed in 2018. This ship will be powered by LNG and will be significantly different to the other four.”