The storm, which had left the Bahamas heading northwest by the afternoon, should become a Category 3 storm with winds up to 130 mph by Monday, forecasters projected.
But Dennis' path still was not clear. It could make landfall around Tuesday, most likely somewhere in the Carolinas, forecasters said.
However, it also could veer away from land.
"There's some glimmer of hope," said Jerry Jarrell, director of the National Hurricane Center in Miami. "Some of the (computer) models are beginning to show that it may miss the coast."
Jarrel said current forecasts show the hurricane's core passing about 100 miles off the shore of Florida _ within the radius for 50 or 60 mph winds. "That suggests that they're going to get strong winds (in Florida) and they're really going to get some strong surf out of this," he said.
Still hundreds of miles away on Saturday, Dennis kicked up 8-foot-high waves along the coast from Florida to North Carolina, delighting surfers but prompting officials to put state troopers and the National Guard on alert. Hurricane watches and tropical storm warnings were issued along hundreds of miles of the eastern seaboard.
At 8 p.m. EDT, Dennis was centered 170 miles east of Florida's Cape Canaveral. It packed sustained winds of 105 mph with higher gusts, up from 80 mph the night before.
The storm broadened during the day, with hurricane winds that had extended 40 miles from its center stretching to 60 miles. It was crawling on a west-northwest track at close to 7 mph. Its tropical storm winds extended another 160 miles.
Jarrell said he was worried because three projections showed Dennis stalling again somewhere between Georgia and North Carolina's Outer Banks with winds of 115 to 130 mph. The storm had hovered for hours overnight as it crept alongside the Abaco islands in the Bahamas.
After the storm had moved on and hurricane warnings were lifted, the residents of Grand Abaco, a sliver of land no more than 10 miles wide with a population of several thousand, assessed the damage.
Just back from a drive around Grand Abaco's Marsh Harbour, the Rev. Carlton Dorsette said about 70 percent of the walls were down on a commercial building under construction and his own house under construction was "totally down."
"There wasn't much rain but lots of wind. I think we probably got a direct hit last night," he said. "Lots of trees have fallen, power lines are down, a lot of phone lines are damaged, cable lines are damaged."
A number of boats had gone under in the harbor, but the airport looked unscathed, Dorsette said. The Bahamas Air Sea Rescue Association said it had heard reports of several boats breaking their moorings and smashing onto rocks.
Hubert Tate, a fisherman at Sweeting's Cay in the Abacos, said the storm damaged banana and other fruit trees, smashing some to the ground. It ripped the shingles off some roofs and tore down shacks.
A hurricane watch remained in effect for the east coast of Florida from Sebastian Inlet northward to Fernandina Beach.
People began preparing for the storm, stocking up on supplies and lumber. The Federal Emergency Management Agency said it was stocking up on water and other necessities at regional centers.
In South Carolina, Gov. Jim Hodges ordered 1,000 National Guard troops and 500 state troopers to prepare for duty, but no decision has been made on whether to evacuate people from the coast.
In North Carolina, 150,000 coastal residents were put on alert, as were state troopers and emergency management personnel.
The South Florida Water Management District lowered water levels in
canals to lessen the risk of flooding in heavy rains.