The Kulluk is sitting on the southeast coast of Sitkalidak Island, an uninhabited island separated by the Sitkalidak Strait from the far larger Kodiak Island to the west. The nearest town, Old Harbor, is across the strait on Kodiak Island; it has a population of about 200 people. The strait is home to a threatened species of sea lion.

A spokesman for the Interior Department’s offshore drilling safety office would not say whether the latest problem would cause a re-evaluation of the agency’s approval of Shell’s overall Arctic program. But the spokesman, Nicholas Pardi of the Bureau of Safety and Environmental Enforcement, said that any equipment Shell proposes to use off the Alaskan coast must meet federal safety and testing standards. He added that regulations require a federal inspector be present around the clock during drilling operations.

The other ship Shell has used in the Arctic, the Noble Discoverer, has had problems of its own. In July, before sailing to the Arctic, it nearly ran aground after dragging its anchor in the Aleutian Islands. Then in November it had a small engine fire.

Later that month, during an inspection in the Alaskan port of Seward, the Coast Guard found more than a dozen violations involving safety systems and pollution equipment. Last week, the Noble Corporation, the Swiss company that owns the 512-foot-long drillship and is leasing it to Shell for $240,000 a day, said that many of the problems had been repaired and that the ship was preparing to sail to Seattle to fix the remainder of them.

Critics said that the accident confirmed their worst fears about Shell’s Arctic project and should force federal regulators to stop it.

“We’re learning that oceans, while beautiful, are dangerous and unforgiving,” said Michael LeVine, senior Pacific counsel for the environmental group Oceana. “Shell has demonstrated again and again that it’s not prepared to operate in Alaskan waters. Hopefully something good will come out of this latest incident, and the government will take a careful look at whether activities such as this can be conducted safely, and if so, what changes are needed to make that possible.”

Shell was on the verge of drilling in 2011, but delays in getting final approval for an air quality permit forced the company to put off drilling until 2012. More equipment failures and unpredictable weather continued through the year. In September, Shell had to abandon preliminary drilling in the Chukchi Sea when sea ice moved toward the drilling area only a day after work began.

And finally, the company was forced to put off completing the two wells it had begun to drill for another year when a barge containing a spill containment dome was badly damaged during a testing accident. During the testing, a mechanical device malfunctioned as the containment dome was lowered into the water, and a submarine robot became tangled in some of the dome’s anchor lines.