Royal Caribbean perfects the art of sailing on air

Richard Pruitt talks to ICFR onboard Royal Caribbean International’s second Quantum-class ship
Royal Caribbean perfects the art of sailing on air

By Michele Witthaus |


This article was first published in the AAutumn/Winter 2015 issue of International Cruise & Ferry Review.

There are many advantages to being the second vessel in a new series – even one following hot on the heels (stern?) of the other, just six months later. “Technically the ship is essentially the same but we’ve really learned a lot on the operational side when it comes to operating the scrubbers,” says Richard Pruitt. The company will incorporate these and other insights into its retrofit programme in which nineteen different ships will be fitted with a total of more than 60 scrubber towers. “We’re always looking further down the road. Our vendors learn a lot as well as our crews.”

Another system that has benefited from a few months in the water is the groundbreaking air lubrication system. “I think this system is fantastic,” says Pruitt. “To be honest, it’s old technology but because we didn’t have the computing power in the past to get the computational fluid dynamics calculations and analysis right, it was never really commercially viable until now.”

Advances in this field led to a partial ship trial on Celebrity Reflection that was promising enough to justify full installations on Quantum and Anthem. “The results on Quantum were so good that the company decided to retrofit Allure of the Seas with an air lubrication system during her drydock in the summer,” he adds.

“The idea is to create extremely small micro bubbles, like champagne bubbles. What you want is the bubbles to stay under the ship because obviously when they go up to the side they lose any effect. So it’s about the design of the mesh – the matrix that puts the bubbles out – and the perfect velocity of the air to create these tiny little bubbles.” Tiny they may be, but they certainly pack a punch. On Quantum, he says, “depending on the speeds, we’re realising energy efficiency gains of better than 5%. When we start talking about gains for propulsion greater than 1% or 2%, that’s fantastic.”

Anthem and Quantum also benefit from an unexpected but very much appreciated side effect from the air lubrication system. “These bubbles travel along the bottom of the ship and then when they go towards the stern, what we’re finding is that the layer of air is essentially an air pillow. So it actually reduces the noise of the propellers, which throw off a pressure pulse like a little sonic wave in the water when they spin. The air bubbles act like a pillow so the sound wave is compressing the air rather than striking the metal.

“So we’re maintaining the fuel efficiency having less propeller noise and now with the air lubrication system we’re reducing the noise from the propellers even more. It’s great when you see one technological advance solve two problems. And we didn’t have to pay for the noise dampening.”

Like her sister vessel, Anthem was built to ensure safe return to port (SRtP), says Pruitt. “That requires a significant amount of segregation and redundancy – and equipment. It’s more than hardware; it’s practices, procedures and checklists.” Royal Caribbean worked with independent contractor Safety at Sea to develop a software package that ensures SRtP: “If we’ve had an incident in one compartment, it tells us what actions we need to take and what system degradation we can expect.”

Pruitt is also closely involved with the Oasis-class newbuilds. How different are those ships going to be from the Quantum class? Pruitt says Harmony of the Seas will be 21-24% more fuel efficient than Allure of the Seas (built six years earlier). He credits RCL’s EVP, Maritime & Newbuilding with driving progress in this arena. “Harri Kulovaara’s team has an internal goal of trying to improve energy efficiency by 4-5% a year and we’re approaching that,” he says.

Looking at maintenance and improvement for the older ships across the different brands, “energy efficiency is an imperative,” says Pruitt. “It’s a way of taking the technology and the learnings from the newbuild process and rolling it back to the existing fleet.”

Complexity goes with the territory when retrofitting technology. The first scrubber tower has been installed on Celebrity Solstice, a project that required ongoing works while in service. “This ship has four engines and so to install a scrubber you have to take an engine out of service, because you have to remove the silencer to start working on the actual scrubber,” says Pruitt. “It’s something that we take very seriously, there’s tremendous planning and a lot of focus on it from everybody in the scrubber team.”

One pleasing result of all this work was that Royal Caribbean’s brands were granted formal exemptions to the North American ECA rules by the United States and Canadian governments.

“When we first started looking at exemptions, there were virtually no ships with scrubbers so the US and Canadian governments viewed it – I think wisely – as a way of facilitating market forces,” explains Pruitt. “You have to create a market momentum so that owners are comfortable buying and manufacturers will build.” Working with a number of different integrators was also important. “We have to be able to go out to a third party and say: We need you to work with the scrubber manufacturer and our technical people to fit this huge piece of kit into our ship – and oh, yeah, it’s while it’s in service. That takes tremendous capability and competency of the integrators.”

The results were positive on many levels. “We were extremely happy with the level of cooperation that we got from the US, Canadian and French governments and our flag states Bahamas and Malta when we did this work. Actually it was a great example of public/private partnership.”

The Quantum class is also pioneering a new ballast water treatment system, says Pruitt: “The international treaty has not yet been ratified by enough countries so it’s not enforced. We’ve gone on a little bit of a leap that we’re going to trust in it. This is on top of a bit of confusion because right now the US has a whole different set of standards for ballast water. And even in the same country, the US Coastguard and EPA standards are different. So the standards are different. But we’ve made the commitment to go ahead and install.” This commitment is in keeping with the company’s policy of going above and beyond compliance requirements – and will certainly add to the tasks on Pruitt’s to-do list in the months to come.

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