ANCHORAGE — A towing plan for a Royal Dutch Shell PLC drill barge crossing the Gulf of Alaska in December called for moving the vessel to a protected bay or heading for deep water if an extreme storm hit, the official who approved the plan said Tuesday.
Norman “Buddy” Custard, the Shell Alaska operations manager for the tow, said the company reviewed historic storm data and gave the go-ahead for the 18- to 24-day voyage in mid-December despite having a weather forecast out only 72 hours.
“When we left Dutch Harbor, there was no forecast of 35-foot seas,” he said. “So at some point in time, you have to make the commitment to get underway, based on the available data we had, and the available forecast we had, understanding that we could encounter some storm systems out there.”
Neither seeking shelter on the coast nor riding out the storm in deep water ultimately was an option.
The Kulluk, a 266-foot diameter drilling barge with a 160-foot derrick rising from the center, broke away from its towing vessel in 20-foot swells Dec. 27. Multiple attempts to maintain tow lines failed, and the vessel ran aground Dec. 31 off tiny Sitkalidak Island, just off Kodiak Island.
Custard testified during the second day of Coast Guard hearings on the grounding.
The 30-year Coast Guard veteran was hired by Shell six months before the grounding. He estimated that he had personally overseen dozens of tows when serving with the agency, mostly in emergency situations, and often in conditions faced by the Kulluk and its 360-foot towing vessel, the Aiviq.
The decision to begin the voyage, he said, was not influenced by the need to move the drill vessel out of Alaska waters to avoid a state tax liability. Shell was interested in having the Kulluk reach the shipyard to ready the vessel for the 2013 drilling season, he said, but the safety of 18 people riding on board was the ultimate consideration.
Winter storm potential, Custard said, was mitigated by identifying safe harbor locations along the route and planning for moving to deep water to ride out a storm, he said.
The initial tow line separation was caused by a failure of a shackle parting from a towing plate on the Kulluk. The shackle, rated for towing 120-tons, has not been found.
The Coast Guard panel, which includes representatives of the federal Bureau of Safety and Environmental Enforcement and the National Transportation Safety Board, focused questions on Shell’s towing equipment and procedures.
Capt. Marc Dial, the towing master for the Kulluk’s trip north in June 2012 from Seattle to Dutch Harbor, testified that the barge’s design made the vessel unique, like towing a saucer for a teacup. The shape at times caused the vessel to oscillate in an elliptical orbit, but the motion did not affect towing load.
Dial, who has overseen approximately 100 tow jobs of drilling rigs, said he prefers moving them with two towing vessels but the Aiviq and the equipment it carried was more than equipped for the job he oversaw.
“There wasn’t much an escort vessel could do,” he said.
Panel members questioned Dial on capacity of the steel cable that makes up the tow line plus the “jewelry” — the buckles and shackles holding it in place, and the forces that could make them bend or break.
Dial said he was not qualified to say what he would have done to prevent the grounding.
“I have received no documentation with respect to the incident,” he said. “I have no knowledge of it whatsoever,”
The marine casualty investigation hearing will continue Wednesday and could last two weeks.