More than 15 hours of searching for a boater who went missing in the waters off Sands Point was unsuccessful Thursday and U.S. Coast Guard officials said they were calling off the effort.

Scott Donsavage, 43, of Pleasantville in Westchester County, was last seen by his wife Wednesday about 10 p.m., before he got under way from Pleasantville aboard his 15-foot Chris Craft.

The Coast Guard said it had searched more than 276 square miles in the Long Island Sound, or an area roughly eight times the size of Manhattan.

Nassau police aviation and marine units assisted, the Coast Guard said.

The Coast Guard has deployed a cutter, rescue boats from Kings Point and Eatons Neck, and flown in helicopter crews from stations in Cape Cod and Atlantic City.

Donsavage is about 5 feet, 11 inches tall and weighs 180 pounds. He was wearing a black shirt, red hat and shorts.

"We don't know if he was wearing a life jacket. If he had it on, that would certainly help locate him and keep him afloat," Coast Guard spokeswoman Jetta Disco said.

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