ANCHORAGE, Alaska — A Shell drill ship drifted perilously close to land Monday night after breaking loose from two tow vessels in a severe Gulf of Alaska storm.

The Kulluk, one of two Shell drill ships that operated in U.S. Arctic waters in 2012, was confirmed adrift at 7:15 p.m. It had been under tow by a tug and a 360-foot anchor handler.

The vessel first separated from a towing vessel Thursday night south of Kodiak Island. Repeated attempts to control it in the rough North Pacific have been unsuccessful.

A unified joint command center overseeing the incident on Monday afternoon had announced the vessels would try to ride out a storm with predicted winds of 69 mph and waves to 40 feet rather than continue an attempt to move to shelter on Kodiak Island.

“The weather is so severe, we decided to hold our ground and wait till it moves on,” said Shell Alaska spokesman Curtis Smith while the vessels were still connected.

The Kulluk’s exact location was not immediately disclosed, though the command center said it was estimated to be about four miles from land.

The command center said safety of personnel involved and the environment remained the top priority of incident commanders.

The Kulluk is designed for extended drilling in Arctic waters and underwent $292 million in technical upgrades since 2006 to prepare for Alaska offshore exploration. The drill ship worked during the short 2012 open water season in the Beaufort Sea off Alaska’s north coast. It’s ice-reinforced, funnel-shape hull can deflect moving ice downward and break it into small pieces.

Attached to a drilling prospect, the Kulluk is designed to handle waves 18 feet high. When disconnected from a well, it’s designed to handle seas to 40 feet.

The vessel Thursday was carrying a skeleton crew of 17 as it was towed from Dutch Harbor in the Aleutian Islands to Seattle for maintenance. The tow line broke at a shackle attached to one of the vessels.

“It was new. It was inspected before it left Dutch, but it broke,” Smith said.

The Aiviq crew alerted the Coast Guard and the cutter Alex Haley from Kodiak motored to the vessels. Two vessels under contract to Shell also left from Seward.

Before a line could be reattached, the Aiviq’s engines failed, possibly from contaminated fuel. The Alex Haley attempted to secure the drifting drill ship but that line failed and wrapped itself around one of the cutter’s propellers, requiring the cutter to return to Kodiak on one propeller.

With additional heavy weather predicted, the Kulluk crew was evacuated Saturday from the heaving drill ship. Crew members hooked up emergency tow lines and left them trailing behind the vessel in case they were needed.

The Aiviq, with its engines restored, and a tug re-established lines to the drill ship, only to have the lines break Sunday afternoon.

At about 12:45 a.m. Monday, during a lull in the storm, the crew of the Valdez-based tugboat Alert grabbed the original 400-foot line trailing the free-floating drill ship. Later in the morning, the Aiviq, the anchorage handler that was towing the Kulluk by itself Thursday, grappled aboard one of the emergency lines.

The vessels had moved north toward Port Hobron on Kodiak Island before the unified command, made up of Shell, the Coast Guard, state authorities and the operator of the Aiviq, Edison Chouest Offshore, decided to halt the transit. Port Hobron is on the southeast side of Kodiak Island.