ANCHORAGE, Alaska—Royal Dutch Shell PLC will try to move its grounded drill ship out of the worst of the North Pacific's fury with a towing attempt when conditions allow.

Shell incident commander Sean Churchfield said at a press conference Saturday that naval architects have pronounced the Kulluk fit to be towed. The attempt will depend on weather, tides and readiness, he said.

"I can't offer you firm times. Right now, the preparation for the tow depends on the weather and operational constraints," Churchfield said. "We will be looking to move the vessel as soon as we are ready and able."

If the drill ship can be pulled from the rocks off Sitkalidak Island, it will be towed 30 miles to shelter in Kodiak Island's Kiliuda Bay, a cove about 43 miles southeast of the city of Kodiak.

The Kulluk is a circular barge 266 feet in diameter with a funnel-shaped, reinforced steel hull that allows it to operate in ice. One of two Shell ships that drilled last year in the Arctic Ocean, it has a 160-foot derrick rising from its center and no propulsion system of its own.

The tow attempt will be made by the same vessel that lost the Kulluk last month while attempting to move it to Seattle. A line between the 360-foot anchor handler, the Aiviq, and the Kulluk broke Dec. 27. Four re-attached lines between the Aiviq or other vessels also broke in stormy weather.

The attempt to rein in the drill ship was complicated by engine failure experienced by the Aiviq's four engines. A preliminary investigation pointed to bad fuel but that is not conclusive, Churchfield said. The Edison Chouest Offshore crew has treated fuel and changed filters.

"Thus far, we have not seen a repeat of those problems," he said.

Fuel tanks remain intact on the Kulluk and there are no plans to remove an estimated 150,000 gallons of diesel from the Kulluk, which would present a different set of risks, Churchfield said. Other cargo also will remain.

Coast Guard Capt. Paul Mehler, the federal on-scene coordinator, said no divers have been in the water but soundings from small Coast Guard boats and discussions with local fishermen indicate the vessel rests on a rocky bottom.

Not every piece of equipment was in place Saturday afternoon, he said.

"The two that I know, we have a large generator and we have a piece of a tow connection. It's actually an expandable piece that would do the gig. That's the key piece we're missing right now," Mehler said.

More than 600 people were working on the recovery.

Dan Magone, who has worked on other major groundings in Alaska, a day earlier expressed skepticism that the vessel could simply be towed.

"I'd really be shocked if this thing is so lightly aground and so lightly damaged that they can just go pull this thing off right away," said Magone, president of Magone Marine, in a telephone interview from his headquarters in Dutch Harbor.

Magone is not working on the salvage of the Kulluk but has experience with other major groundings, including the Selendang Ayu, a cargo ship wrecked in December 2004 on Unalaska Island. Smit Salvage, the Dutch company hired to salvage the Kulluk, also worked on that wreck.

Magone's company is under contract for two other wrecks—fishing boats from which fuel has been removed—but he's waiting until spring to finish the job. That's often the routine for winter groundings in the region, he said.

"The insurance company doesn't want to pay any more money than they have to to get the wrecks out of there, so why risk our equipment and our crew and spend a thousand percent more money playing around in the wintertime when you can just wait until the weather's good and do it then?" Magone said.

"That's pretty normal. Of course with a big fiasco like this, there's all kinds of pressure and everything. But there's a limit to what you can do," he said.

Shell has reported superficial damage above the deck and seawater within that entered through open hatches. Water has knocked out regular and emergency generators, but portable generators were put on board Friday.

The condition of the hull will be key in determining whether the Kulluk can be refloated. 

The Coast Guard must review and sign off on a salvage plan. Brian Thomas of the Coast Guard's salvage engineering response team in Washington, D.C., said the team's marine engineers give technical advice and assess risks.