ANCHORAGE — A Coast Guard panel investigating the Alaska grounding of a Royal Dutch Shell PLC drill barge focused questions Tuesday on a key piece of tow line gear that has not been recovered.
Investigators quizzed a Shell contractor on the condition of a metal shackle in the tow line that connected the Kulluk, a 266-foot diameter barge, to its towing vessel, the Aiviq. When the tow line broke Dec. 27, the shackle was missing and presumed to be on the bottom of the Gulf of Alaska.
William Hebert of Louisiana-based Delmar Systems, Inc., said no flaws in the shackle had been detected when the Kulluk left Dutch Harbor six days earlier.
“I would have reported it and made a suggestion to exchange it,” he said. Any good rigger or inspector overseeing such an operation would have removed such a piece if flaws had been detected, Hebert said.
A shackle is a U-shaped piece of metal used to make a connection between lines and metal parts. A cotter pin connects the ends of the U to form a loop. For the Kulluk tow, the missing shackle was the connection between the Aiviq and a metal “tri-plate” that held two smaller shackles and lines leading to the drill rig.
Besides finding out what happened with the Kulluk, investigators are reviewing systems to determine how Shell and its contractors chose, monitored and inspected towing gear or whether equipment became fatigued on trips through the Gulf of Alaska and the Bering and Chukchi seas.
Delmar Systems was hired to oversee mooring of the Kulluk in port and on a drilling site in the Beaufort Sea. Hebert testified that he was on hand last summer in Seattle when a shackle rated at 85 tons was switched out at the request of a tow captain for the more rugged 120-ton shackle.
The apparently new shackle was taken from a crate in a Shell “lay-down” area in Seattle, he said.
The shackle was used for the northbound tow of the Kulluk from Seattle to Dutch Harbor and then across the Chukchi Sea to the Beaufort.
It was still in place when the Kulluk was towed back to Dutch Harbor after the summer drilling season ended.
Hebert flew on Dec. 19 to Dutch Harbor and looked over the tow gear, which included the shackle, as did a warranty surveyor on behalf of Shell’s insurance underwriters. Herbert saw no signs of wear or improper assembly, he said.
Coast Guard investigator Keith Fawcett questioned Hebert about the positioning of the arms of the cotter pin in the shackle, and whether their 90-degree angle could have caused them to be beaten up by other parts of the towing equipment or snagged on something in the water.
“From my recollection of it, it was in suitable condition,” Hebert said, with no deformity or rust, despite being in saltwater conditions for about six months.
The 3-inch diameter pennant, or tow line, was rated for 85 tons and should have been a weaker link in the line, Herbert said in answer to a question from Eric McVittie, an attorney for Edison Choust Offshore, the operator of the Aiviq.
The tow line between the Aiviq and the Kulluk parted Dec. 27. Repeated attempts failed to maintain an emergency line or other lines and the Kulluk ran aground Dec. 31 off tiny Sitkalidak Island. The Aiviq pulled the barge off six days later. It has been moved to a shipyard in Singapore for repairs.
Hearings ended early Tuesday. A scheduled witness, John Becker of Offshore Rig Mover’s International, the towing master for the ill-fated voyage, was not available to appear, Coast Guard officials said. The panel will resume the hearing Wednesday.