Superstorm Sandy caused significant marine- and energy-related losses that included a huge transformer explosion in Manhattan and the grounding of a tanker on Staten Island.

However, “It is still very early in the damage assessment process to have a clear picture of impact on the marine and energy insurance markets,” Bobby E. Bierley, Houston-based vice president and account executive with Lockton Marine & Energy, said in an email. For energy, “We do not view this as a market-changing event at this time. Marine will require a bit more time for assessment,” he said.

During its peak, more than 8 million U.S. customers reportedly were without electricity along the Eastern Seaboard. The Nuclear Regulatory Commission said Friday that all nuclear power units shut down as a result of the storm have been restarted.

Bertil Olsson, Houston-based North American energy, mining and power practice leader for Marsh Inc., said damage to the oil and gas sector is restricted mainly to terminals and storage facilities.

“We're not aware of any refineries that sustained any major damage,” Mr. Olsson said. However, there is widespread utility damage “so we do believe there's going to be an impact there on the market.”

Carlos Carrillo, Houston-based regional head of energy for Allianz Global Corporate & Specialty, a unit of Allianz S.E., said that because of the oil, gas and petrochemical operations and heavy machinery and equipment that Allianz insures, damage “most likely is going to be from flooding” and water rather than from high winds.

%%BREAK%%

The key to business interruption losses due to the power outages depends on how fast clients can do “the repairs necessary to bring the facilities back up,” he said.

“There's going to be quite a lot of insured losses right there in the energy sector,” said Gary Thompson, a partner and insurance recovery attorney with Reed Smith L.L.P. in Washington. “New Jersey is a major hub for oil refining and gasoline distribution,” and “there is physical damage from the storm surge and wind, but also probably much larger business interruption losses that will be insured somewhere upstream.”

Mr. Carrillo said, however, that the “energy industry is well prepared to weather this kind of event, because they do have a well-established risk management program” in the event of a hurricane, in which they usually shut down facilities close to the coast before such a storm strikes.

Discussing losses in the marine sector, “We couldn't even hazard a guess at this point in time, certainly, given the extent of this storm,” said Kevin Wolfe, New York-based head of the marine northeast region and global head of Project Cargo for Allianz. “I'm fully expecting high activity with respect to claims.”

“This storm caused substantial disruption in shipping plans,” Mr. Thompson said. Like flight disruptions, shipping schedules that get disrupted have “a ripple effect that goes around the globe, so the negative financial impact on the marine side will be substantial, well beyond the immediate physical damage.”

“There's massive damage to the ports in Elizabeth (N.J.), and up down the New Jersey and New York coastlines,” he said.

%%BREAK%%

Ships also head out to sea during hurricanes to avoid damage, industry observers said.

Alan Rubin, a government relationships specialist with law firm Cozen O'Connor in New York, said that while marine losses are expected to be substantial, moving ships out to sea can help reduce losses.

“If a ship is moored next to shore, and they get hit” by a big wave, “it's got nowhere to go, it can tilt over,” he said. “You're better off taking your chances by running out to sea and see if you can outrun it.”

In the aftermath of the hurricane, a news report showed footage of a nearly 170-foot water tanker that ran aground in Staten Island, N.Y., on Monday night. There was also reports of a transformer explosion at a Consolidated Edison Inc. plant on 14th Street in Manhattan.

Guy Claveloux, New York-based managing director at Marsh, said there has been “an abundance of (insurance) capacity in the marine sector,” with rates that were still trending downward.

“It's hard to say right now what's going to happen to rating in a market that is still quite soft,” Mr. Claveloux said.