When drifting sea ice jammed their supply boat against an offshore oil platform -- and then started piling up on deck -- the seven crewmen realized they had no choice but to abandon ship and fast.
So they did, clambering up a catwalk on the platform as the boat swamped and ultimately sank Thursday in the frigid waters of Cook Inlet, said spokesmen for the boat's owner and the U.S. Coast Guard.
"It was so dynamic. The ice took over the vessel from the stern. It pinned it up against the legs of the platform and then just started to collect on the deck of the boat," said Jim Butler, a Kenai lawyer and spokesman for the boat's owner.
All seven crewmen escaped without serious injury, although the boat's chief engineer needed treatment at a Soldotna hospital for exposure to diesel fuel and inhalation of engine exhaust.
Authorities didn't name the crewmen.
The drama began at 5:51 a.m., when the captain of the supply boat Monarch made a mayday call to the Coast Guard, saying the 166-foot vessel was taking on water.
The boat's crew was delivering supplies to the Granite Point platform on the west side of Cook Inlet near Tyonek. The platform belongs to Chevron Corp.
By afternoon the blue-hulled Monarch was submerged next to the hulking platform, only a bit of its bow poking out of waters choked with ice floes.
The mishap triggered a sizable air and water response from the Coast Guard, and Chevron shut down oil production on the platform. As a safety precaution, the platform was partially evacuated, with seven of its 14 workers going by helicopter to Nikiski, along with the supply boat crewmen, authorities said.
The boat was carrying 35,000 to 38,000 gallons of diesel fuel, plus an unknown volume of hydraulic and lube oil, the state Department of Environmental Conservation reported.
The vessel also carried several totes and drums of chemicals for delivery to Inlet oil platforms.
A light sheen was visible in the calm waters and a cleanup contractor, Alaska Chadux Corp., was responding, the DEC said.
The agency said water at the platform is 86 feet deep, though the depth would vary with the tides.
Coast Guard Petty Officer Sara Francis said experts believe any diesel spilled from the boat should evaporate or disperse within 12 hours in Cook Inlet's strong tides.
"It's a drop in the bucket and not a serious concern," she said.
The main task will be the potentially dangerous job of getting the boat away from the platform for salvage.
The crew of the Coast Guard cutter Hickory this morning plans to use a sonar device to see how the sunken boat is oriented and whether the platform was damaged.
"We have salvage masters coming in from the Lower 48 and overseas," Butler said.
The boat was maneuvering around the platform, which is equipped with a crane to lift supplies, when the ice bulled in, he said.
Luckily the tide was high, allowing the crewmen to reach the catwalk and get clear of danger, Butler said.
The Monarch's owner is Ocean Marine Services Inc. of Kirkland, Wash. It operated out of the Offshore Systems Inc. dock at Nikiski. Butler described the two firms as "sister companies."
He also said the Monarch recently underwent substantial maintenance work in a shipyard, though he said he didn't know where.
Granite Point is one of the northernmost of Cook Inlet's 16 offshore oil and gas platforms. It was built in 1966 and averaged 193 barrels of crude oil production per day in December, said Chevron spokeswoman Roxanne Sinz. Total Cook Inlet oil production is less than 17,000 barrels per day, which is small compared to the North Slope's average of about 750,000 barrels per day.
"Right now we're shut in, which means that we're not producing," Sinz said of the Granite Point platform.
It wasn't clear late Thursday how long the platform would be out of service or whether the Monarch's impact damaged the structure, Sinz said.
Find Wesley Loy's commercial fishing blog online at adn.com/highliner or call 257-4590.
By WESLEY LOY
wloy@adn.com