MOBILE, Ala. – The winds and waves eased in the Gulf of Mexico on Tuesday, an encouraging development for crews trying clean up a massive oil spill, yet an official with BP PLC said more than 20 boats were looking into an unconfirmed report of oil coming ashore in Louisiana.

People along the beaches and bayous waited anxiously to find out just how badly it might damage the delicate coast.

A Coast Guard official said forecasts showed the oil wasn’t expected to come ashore for at least three more days and that the calm weather was allowing cleanup crews to put out more containment equipment and repair some of the booms that were damaged in the rough weather. They also hope to again try to burn some of the oil on the water’s surface.

“We do have the gift of time. It’s a gift of a little bit of time. I’m not resting,” U.S. Coast Guard Rear Adm. Mary Landry said.

BP Chief Operating Officer Doug Suttles said boats were dispatched to Chandeleur Island to look for the oil coming ashore, but so far haven’t been able to find it.

The Associated Press reported Thursday that some oil washed ashore at the mouth of the Mississippi River along the Louisiana coast.

So far only sheens have reached some coastal waters. The oil has lingered in the Gulf for two weeks, despite an uncapped seafloor gusher.

The slow movement has given crews and volunteers time to lay boom in front of shorelines, an effort stymied by choppy seas over the weekend.

Rig operator BP PLC continued to try to cap one of the smaller of three leaks, which if successful, could make it easier to install a containment system.

BP’s chief executive said a containment dome designed to cover the principal leak will be on the seabed Thursday, and will be hooked up to a drill ship over the weekend.

CEO Tony Hayward stressed to reporters in Washington that the procedure had never been done before at a depth of nearly a mile below the water’s surface.

“So we’ll undoubtedly encounter some issues as we go through that process,” he said. “But if that was a good outcome, then you would have the principal leak contained by the early part of next week. But there’s no guarantees.”

The plan is to cover the leak with a 98-ton concrete-and-metal box structure known as a cofferdam, and funnel the oil to the surface. Hayward also said that chemical dispersants being used on the oil have significantly reduced the amount of oil coming to the surface.

The uncertainty has been trying for people who live along a swath of the Gulf from Louisiana to Florida. The undersea well has been spewing 200,000 gallons a day since an April 20 explosion aboard the drilling rig Deepwater Horizon that killed 11 workers. The rig was owned by Transocean Ltd.

“The waiting is the hardest part,” said Dodie Vegas, 44, who rents rooms at Bridge Side Cabins in Grand Isle, La.