Mooring lines were snapped and approximately two barrels of oil product were spilled into Cook Inlet, Tesoro said. The vessel was later refloated at high tide with the assistance of four tugs and taken to Homer for inspections.

Tesoro spokesman Kip Knudson said inspections revealed a small deformation in the outer hull that allowed small amounts of seawater to enter the ship's ballast tanks. The Seabulk Pride is a double-hulled vessel.

The tanker has the capacity to carry 342,000 42-gallon barrels of oil. When a surging ice floe struck Seabulk Pride and snapped the 16 synthetic lines and cables securing it to a Tesoro refinery loading dock in the early morning, it was carrying 116,225 barrels of diesel, oil and gasoline products.

While the vessel was grounded the Coast Guard was concerned that each time the tide rolled in and out of upper Cook Inlet, there were stresses on tanker's hull with the potential for cracks. The Coast Guard and Seabulk Tankers Inc., the owner, acted quickly to prevent too many tide cycles from occurring before they pulled the tanker away from the beach where it had grounded north of the Nikiski port, said Coast Guard Capt. Mark DeVries at a Feb. 3 press conference.

The accident occurred just days after the coast guard issued extreme ice rules for vessels traveling through Upper Cook Inlet. When the accident occurred, huge ice pans were rushing in and out on one of the strongest tides of the winter.

Heavy ice conditions and strong tides combined to produce some of the most dangerous conditions that can occur in Cook Inlet, said Loren Flagg, who headed the Kenai Peninsula Borough team charged with responding to the Exxon Valdez spill that occurred in 1989.

"I just don't understand why they were operating under those conditions," Flagg said.

There were 24 people on board when the tanker broke loose, including two marine pilots, and no injuries were reported. Whether the extreme ice rules were followed is still being investigated.

The Tesoro dock remained closed while repairs were being made, Knudson said. A tanker scheduled for the dock is standing by while the repairs are made. A ship was able to dock at the ConocoPhillips-Marathon dock to take on liquefied natural gas, but a single-hull vessel bound for the Agrium Corp. dock was delayed.

Since the Feb. 2 accident, the extreme ice rules have been amended so that vessel traffic into Cook Inlet will be approved on a ship-by-ship basis, said Sara Francis, a petty officer for the Coast Guard.

After an assessment of its equipment, it was determined that the Arctic Sun, a boat arriving from Tokyo to load liquefied natural gas from ConocoPhillips, was prepared to enter the Nikiski port under current conditions, the Coast Guard said.

The Arctic Sun has a ice-reinforced double hull and winches with tension monitors, used to inform the ship's crew when the tension on the moorings has become too great.

The Seabulk Pride did not have an ice-reinforced hull or tension monitors, but there were strain gauges on the dock and the brakes on the Seabulk Pride's winches had last been inspected only a week prior to the accident, according to Seabulk Tankers Inc. public affairs officer Jim Butler.

The extreme ice rules also have been amended so that a spotter ship, the Monarch, was within a few miles of the dock when the Arctic Sun arrived.

"Like spotting a climber, they'll be spotting the Arctic Sun," she said. "They're like another set of eyes."

The Monarch's crew monitored ice floes and conditions for the Arctic Sun.

While the dock is closed, the Tesoro refinery is operating at a reduced capacity.

The accident has renewed calls for increased navigational safeguards in Cook Inlet and, in particular, tugboat assists.

Heavy winter ice can become particularly dangerous in Cook Inlet due to its notoriously strong, fast tides, but in contrast to Prince William Sound and Puget Sound, Cook Inlet safety standards do not require tugboat assist availability for tankers.

"We dodged a big bullet here, and this should be a wake-up call that Cook Inlet navigational safety needs to move into the 21st century," said Bob Shavelson, executive director of Cook Inlet Keeper.