In SF Bay, towing ultralarge ships with little tugboats

Maritime agencies run a first-ever test of pulling a giant ship with a tiny tug. Knowing it's possible is key in a power loss.

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A tugboat pulls an ultralarge container vessel, carrying 11,000 containers, in a San Francisco exercise last Wednesday. Daniel Terdiman/CNET

SAN FRANCISCO BAY -- It's a terrifying notion: A giant container ship loses power at the mouth of the Golden Gate and drifts toward the nearby Headlands, threatening the sensitive ecosystem with an oil spill that could kill thousands of birds and cost millions of dollars to clean up.

Though a scenario like that hasn't happened, it easily could, especially since the passage in California of clear-air legislation that mandates ships use less-polluting diesel fuel when in state waters. That requirement has resulted in increasing cases of the vessels' engines unexpectedly shutting down, because they weren't built to process diesel, says Deb Self, executive director of San Francisco Baykeeper, a proponent of clean-water laws.

Local officials have worried that they wouldn't know how to handle such a situation, which could become a big problem as larger and larger container ships make their way into estuaries like the San Francisco Bay.

That's why, last Wednesday, a group of maritime organizations -- state, industry, nongovernmental, and others -- under the umbrella of the Harbor Safety Committee carried out a first-of-its-kind exercise in the bay: Using a tugboat to tow a powerless ultralarge container vessel (ULCV), and demonstrating in the process that all the related agencies know how they must work together in case emergency strikes.

Emergencies can come in many colors, of course. In 2007, a container ship called the Cosco Busan hit the Bay Bridge in heavy fog, resulting in a spill of nearly 54,000 gallons of bunker fuel, and the deaths of more than 2,000 shorebirds. That accident, while different than what Wednesday's exercise was meant to handle, is still on the minds of most people in the local maritime industry.

In the past, there have been similar exercises in the US, but never before with an ULCV, said US Coast Guard commander Jason Tama. The largest category of container ship, ULCVs can carry more than 14,000 containers, and in coming years, ships capable of moving between 18,000 and 20,000 of the ubiquitous metal boxes will be coming into ports around the US and the world. With those larger ships come bigger dangers.

The exercise was quite simple. Using as its guinea pig a ship known as the CMA CGM Centaurus, packed with 11,000 containers and heading to Russia from the Port of Oakland, the Harbor Safety Committee brought in three large tugboats (large for tugs, but still small relative to the container ships), and simulated what to do if an ULCV lost power in the bay. "In San Francisco, we have a very engaged maritime industry that works together," said Tama. "The Cosco Busan accident was a disaster for everybody. A problem for one is a problem for all. So we want to get together and [learn how] to do it right."

The exercise

To begin with, the CMA CGM Centaurus powered itself to an area in the middle of the bay, where it shut down its engines, and was tethered to a large tugboat. Then, it was towing time.

For about an hour, the tugboat pulled the giant ship, loaded seven (visible) layers high with a multicolored assortment of containers stacked 18 columns across and 21 columns from front to back. Organizers didn't know how fast the tug could pull the ship, but it ended up moving at a clip of about 4 knots, or 4.6 miles an hour. Eventually, everyone slowed down, and it was time to turn around. Using two tugs, one pushing the ship on the side, and the other pulling, they spun it around, and head back toward where they'd started.

This time, they towed it with two tugs, and they managed to get up to 6 knots, or 6.9 miles an hour. After about 30 minutes of that, everyone was happy, and it was time to let the ship go on its way.

The initial feedback was that the exercise was a success. "We accomplished everything we set out to accomplish," Tama said. "We took [a ULCV] under tow with the assets we have in the Bay...I'm sure there will be lots of nuances, which will come out in a debrief. No exercise like this ever goes perfectly."

The exercise, conducted in near perfect conditions, didn't simulate the kinds of rough weather or low-visibility that can hit the San Francisco Bay. Asked if that was a problem, Tama used a firefighting analogy: While you may want to practice in burning buildings, that's not very practical, or safe. As for the towing operation, "It's better to do the best you can under controlled conditions," Tama said, "so you're ready under more adverse conditions."


 

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