Chantiers de l’Atlantique vice president of projects and ship performance reveals the groundbreaking design of Celebrity Edge's multi-purpose venues and opens up on how its high energy efficiency was achieved
Celebrity Cruises’ Celebrity Edge is due to debut in December this year and among the features that stand out are its multi-purposes venues, especially its Magic Carpet – the world’s first cantilevered platform that reaches heights of 13 storeys above sea level.
The first of the Edge-class ships is being completed by Chantiers de l’Atlantique, formerly STX France, for delivery in October. The shipyard’s vice president of projects and ship performance Stéphane Cordier told Passenger Ship Technology “There are not many ships where so much effort has gone into the design of every single venue and that is what will make the ship really special.”
The Magic Carpet concept came out of a discussion between Celebrity Cruises and Chantiers de l’Atlantique in the shipyard prebid phase. Celebrity Cruises insisted that one of the main characteristics of the ship be the access platform to tenders. “They wanted a ship that could go to places other ships of that size cannot call due to minimum harbour facilities,” Mr Cordier said.
He added that the tenders themselves represented a “big development”.
“They are of high standard, speed, autonomy, comfort and capacity. The eight tenders, which also double as lifeboats, represent a large investment. We tried to make them as sleek as possible, with a higher standard of seating,” Mr Cordier explained.
Therefore, the shipyard consulted with manufacturers to find a product to suit these standards and the proposal from Harding (now Palfinger) was chosen.
There was also the issue of embarkation. “Celebrity Cruises’ wish was that passengers would board tenders in a very comfortable way, not boarding them through technical spaces but going through spaces decorated to the ship’s standard.”
The tender platform needed to handle two tenders at a time, so the issue was to integrate a very large platform accommodating two tenders at the waterline, but there was an obstacle in this case: “Usually the platform is recessed into the hull but the size of the platform is so large (30 m by 6 m), that it could not be integrated into the hull at that level,” said Mr Cordier.
Magic Carpet concept
And this is where the idea of the Magic Carpet evolved – to make it more than just a tender platform. “We had the idea of storing it higher and then potentially using it in different higher positions, using it as an outside venue complementing decks overlooking the water as well as a tender platform,” said Mr Cordier.
Therefore, the platform has four working positions: water level and decks 5, 14 and 15. The platform is moved by a hydraulic system on two main tracks that run vertically to the top of the ship. “We had to make qualifications and risk assessments for all aspects of safety, noise and vibration.” Risk assessments also included examining loads at water level due to the slamming of waves and boat impacts. “So, we needed stiffness and strength all the way up because it needs to withstand motions and wind loads in storms. Concerning comfort, the sea trials have shown that the vibration levels and wind comfort are remarkable,” said Mr Cordier.
He added “We carried out a lot of work on wind comfort in the different positions, with the shape of the awnings and glass panes around it making sure that people are comfortable while enjoying the best view – there will be a stunning view over the water because the platform is overhanging.”
One thing to emphasise, Mr Cordier said, was that the movable platform is not an elevator. “People are not supposed to be on it when it moves, it is locked in to position with the hydraulic system to ensure safety.”
He summed up the process that led to the Magic Carpet: “It was developed from a very technical object to bring enhanced tendering capacity, to a multi-purpose platform that adds value to the programme of the ship at all times.”
One of the most outstanding features of the ship are the Infinite Veranda staterooms which extend out to the side of the ship with a full cabin-width window opening vertically so that when in the open position, part of the stateroom becomes a balcony. This feature was introduced by Chantiers de l’Atlantique in its Ulysseas exploration ship concept design and proposed for the Edge project. Celebrity took on this concept while adding a pair of light glass doors inside to close off the space close to the window to transform it into a real balcony separate from the stateroom. Besides developing the window, the adaptation of the stateroom in terms of safety, comfort, HVAC and automation was a real challenge and a game-changer in the industry.
Another innovative multi-purpose area is the aft lounge, Eden. This is a space surrounded by glass integrated with a helical ramp which includes areas with sofas, where people can look out to sea or look into the Eden area to watch a show. “It adds a three-dimensional aspect to the space,” said Mr Cordier. The multi-purpose theme is continued, as the Eden space can be used as a lounge, restaurant or showroom.
The challenge when it came to the Eden space is the glass wall, designed by US architects Wilson Butler, which had to be attached to the ship structure and involved “work to ensure there would not be any vibration issues,” said Mr Cordier.
The first sea trials of the ship measured the response of the glass wall in different conditions, including crash-stop manoeuvres and “we could verify that it is very sturdy,” said Mr Cordier.
Another interesting feature is the Solarium with a roof made out of plastic material. The material is so light that not many supportive structures were needed, and it created a “very airy and light” space.
Energy efficiency focus
Moving away from the creation of multi-purpose platforms and areas, the ship is also innovative in terms of environmental friendliness and energy efficiency.
The hull shape is particularly innovative. The result of eight years of work by Chantiers de l’Atlantique, it formed part of its initial proposal to Celebrity Cruises. The shape is unique as it incorporates a bulbous bow within a straight, vertical shape. “We wanted to develop a hull form to reduce the resistance of the ship in sea state but that did not compromise on calm water resistance,” Mr Cordier said. This was achieved by using a state-of-the-art bulbous bow for calm water, combined with the “finer angle achieved with a vertical bow that means less resistance in waves and less excitation in terms of comfort. The overall result as demonstrated in the recent sea trials in heavy weather is remarkable and the response of the ship gives an impression of great seaworthiness”.
The propulsion system includes two 16-MW pods from ABB. This is in contrast to Celebrity Cruises’ previous smaller Solstice-class ships, where ABB pods of 20 MW are installed. Mr Cordier said this illustrates reduced power requirements for the ship, leading to fuel savings. The ship also has an air lubrication system installed to save energy.
The propulsion consists of four main diesel engines and a smaller generator, all provided by Wärtsilä 46F 12Vs and 8Ls. The engines are fitted with scrubbers and SCRs to meet emission requirements.
Mr Cordier said “The four diesel engines allow the ship to operate in all circumstances and a fifth smaller one allows the ship to meet the required performance with one main engine down.”
Chantiers de l’Atlantique has developed and implemented an engine schedule featuring uneven load-sharing between the engines, Mr Cordier explained, as typically the number of diesel engines on board to meet propulsion power load and hotel, are all run at the same load. But on Celebrity Edge, “all but one engine will be running at optimum load in terms of fuel consumption, with one adjusted to match the load requirement. This makes energy consumption more efficient.”
The ship stands out as it is especially environmentally friendly in terms of getting rid of waste, going over and above what is expected. Instead of using incinerators, which are a source of gas emissions, the shipyard looked at alternate solutions to eliminate the need to burn refuse. A solution involving hydrothermal oxidation was used, where the waste is put under high pressure and temperature, which disintegrates the material to form water and dust. Placed in the machinery space, the solution consists of two pressure vessels that have to be loaded, in contrast to being a continuous process.
This is the prototype installation on a ship and part of an R&D effort co-funded by the EU through the Leanship project.
Mr Cordier said “This is a higher investment than using incinerators and reduces pollution to a minimum, as incinerator emissions are not counted in the IMO emissions criteria.”
Heat recovery systems are also being extensively used to recover energy from the diesel. “At the end of the process the water is not that hot, but even this is used to heat the swimming pools,” said Mr Cordier.
Mr Cordier emphasised that energy efficiency control was also applied to variable-speed chillers and fans.
The success achieved by Chantiers de l’Atlantique in reducing energy consumption is based on a method developed in their ECORIZON programme which relies on an analytical model of all the ship's energy-consuming systems. This allows them to simulate the impact of the energy-saving features and make investment decisions based on validated expected returns. On the Edge project, a specific target for energy gain compared to the previous class of ships had to be met. The shipyard achieved this, meaning 20% less fuel per passenger will be used compared to the previous Solstice-class vessels.
Three other Edge-class vessels will follow Celebrity Edge, and there is the potential for a fifth to be constructed as well.