Preparing ballast water

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When early wooden ships needed a lower center of gravity to avoid heeling over and foundering, their crews loaded cobblestones bricks, anchors or spare cannons – anything handy and heavy – deep down in their keels.

This solid ballast had to be shifted, dumped or otherwise manipulated to adjust for the dynamics of loading and unloading cargo, passengers or anything else affecting the ship’s weight and maneuverability.

About a century ago, with the development of steel-hulled ships, water replaced solid materials as the ballast of choice, pumped into and out of holding tanks as needed to provide stability. With this change came unanticipated, insidious problems.

Coastal waters teem with life including microscopic organisms. They’re brought into and pumped out of a ship’s ballast tanks with the water. And if the ballast water is not returned to the same place it was acquired, those life forms may invade places they do not belong.

Such invasive species can destroy native organisms, decimate fisheries, severely damage habitats, spread diseases and generally create environmental havoc.

U.S. and international regulations have sought to curtail the environmental impact of ballast water since the early 1990s, and continue to be bolstered and refined with the expectation that new agreements will solidify by the end of 2016.

As they continue to be solidified, Royal Caribbean has not been idle.

“Currently, all our ships have a ballast water management plan on board and treat their ballast water using the international approved way, what we call ballast water exchange,” says Nick Rose, RCL’s environmental regulatory lead. Using that method – required of all ships visiting U.S. ports – involves flushing any ballast water obtained at a foreign coast and replacing it while in the open sea at least 200 nautical miles from land with a depth of at least 200 meters.

Salinity levels and other factors make it unlikely for coastal organisms to survive at sea, or for those picked up at sea to survive in a coastal environment.

And RCL has already begun take its ballast water management above and beyond compliance by retrofitting its existing ships and equipping newbuilds with purpose-built ballast water treatment systems.

“Water is brought on and sent through multiple layers of filter disks,” Rose explains. Whatever is filtered out is automatically backwashed into the same coastal waters where it was picked up, so there’s no transfer of organisms from one area to another.

After filtering, the ballast water is sent through a UV system that renders nonviable or kills any organisms that have made it through, and from there it is stored in the ballast tanks.

“Once that ballast water is ready to be discharged, whether it’s one day or one month after it’s been taken on board, it’s then sent back through the UV system for final filtration,” Rose says.

RCL is also addressing the issue in newbuild design. Early performance of Oasis-class ships has shown them capable of maintaining stability without discharging seawater, while taking on fuel and other materials in port.