The man in charge of overseeing operations for moving Shell Oil's Arctic drill, the Kulluk, testified before the Coast Guard Marine Casualty hearing Friday, explaining his company's decision to tow the ill-fated conical rig in late December 2012.

Much of the testimony from Shell Alaska Marine Manager John Kaighin focused on the tow plan between the Kulluk and its tug, the Aiviq, for the rig's journey across the Gulf of Alaska. But the rig never made it; instead, a series of events – a horrendous winter storm, multiple tow line disconnections and failure of the Aiviq's engines – caused the 266-foot diameter drill rig to run aground off of Sitkalidak Island late New Year's Eve 2012.

While Kaighin offered insights into the technicalities, he delivered few new specifics on what led to the grounding of the rig hours before the beginning of 2013.

But when asked whether it was "bad luck" or an "act of God" that led to series of events that led to Kulluk's eventual grounding, Kaighin disagreed.

"I think bad luck … you give it a name for some reason," he told investigators. "They were operational failures that we basically worked through to solve."

BACKGROUND: TRIALS, MISHAPS OF SHELL'S ARCTIC DRILL RIG, THE KULLUK

Kaighin was repeatedly asked about the events leading up to the shackle failure on the Kulluk. The shackle's parting was the first in a series of events that led the Kulluk's grounding on Dec. 27. Kaighin was repeatedly asked questions on weather history, tow plans, warrant assessments and Shell management involving the tow. Little of it offered new insights into the operation.

Kaighin did note that the towing gear, which had been used to tow the rigs from Seattle to Dutch Harbor and up to Deadhorse in the earlier season, was rated to withstand both winter and summer travel.

He noted that the shackles were not strength-tested in Dutch Harbor prior to departing for Seattle. They were visually inspected, he said, as per standard practice.

Aiviq engine failure

But testimony Friday indicated there were problems with the Aiviq's engines as well, according to Tracy Chouest, operations manager in Alaska for the tug's builder, Louisiana-based Edison Chouest.

On its return trip from the Chukchi and Beaufort seas, the Aiviq suffered a short power blackout – about five minutes – followed by the failure of an engine, which the crew was not able to bring back online while at sea. Still, with two engines running drive shafts on each side of the boat, it never impacted the movement of the Kulluk.

"We never lost propulsion during the tow," Chouest testified.

That was about 10 days before the ship reached Dutch Harbor. It arrived on Nov. 22. A month later, engine running again, the Aiviq departed for Seattle towing the Kulluk.

Testimony marked day five of hearings conducted by investigators from the National Transportation Safety Board (NTSB), the federal Bureau of Safety and Environmental Engineering, the Marshall Islands -- flag state of the Kulluk – and lawyers from all interested parties.

The Coast Guard, led by Cmdr. Josh McTaggart, is in the process of conducting a marine casualty hearing on the Kulluk. The group hopes to uncover what went wrong and, ultimately, who is responsible for the grounding of the conical drilling unit, considered a centerpiece of Shell's Arctic drilling operation.

All of Shell's drilling plans off Alaska's Arctic coasts have been suspended for the year.

Any recommendations from the hearing will be passed on to Rear Adm. Thomas Ostebo, who will decide whether or not to make changes to regulations or pursue criminal charges.

Testimony continues Saturday.

Contact Suzanna Caldwell at suzanna(at)alaskadispatch.com