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Providing coverage of Alaska and northern Canada's oil and gas industry
April 2014

Vol. 19, No. 15 Week of April 13, 2014

The hemisphere’s most treacherous waters

The likely winter sea conditions in the Gulf of Alaska should give cause for concern for anyone planning a major vessel tow through this challenging region, according to the U.S. Coast Guard’s newly published report on its investigation of the December 2012 grounding of Shell’s Kulluk drilling rig. The report says that a U.S. coastal pilot manual characterizes the northern Gulf of Alaska and the southern Bering Sea as “having among the most treacherous winter waters in the Northern Hemisphere,” with a succession of storms typically bringing rain, sleet, snow, howling winds and mountainous seas.

Apparently the weather study that Shell had contracted for the Kulluk’s tow route had suggested the likelihood of seas as high as 9.2 meters (about 30 feet) and 44.6-knot winds for about 10 percent of the voyage.

Records from the tow operation indicate that, with its conical shaped hull, the Kulluk pitched violently in heavy seas, alternately tightening and slackening the towline attached to the Aiviq, the vessel conducting the tow operation, the Coast Guard report says.

And, although the Aiviq, the vessel that Shell contracted to tow the Kulluk, appears to have been amply powerful to conduct the tow, the Kulluk’s tall infrastructure made the drilling rig particularly challenging to pull against a severe headwind. In the final minutes before the Kulluk ran aground, the tug Alert, a powerful and very capable tug that had come to the Kulluk’s assistance, was unable to make headway at full power in pulling the Kulluk into the teeth of a 40- to 45-knot gale in 20- to 25-foot seas, the Coast Guard report says.

—Alan Bailey






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