A 69-year-old man sailing a 110-foot vessel on the East River was arrested Wednesday and hauled off by cops after they discovered a cache of unlicensed weapons in a locked vault under the deck, sources said.

Jacob Antwerpen, a car dealer from Annapolis, Md., was heading to Boston with a crew that included his wife and daughter on a boat named “YES” when the Coast Guard stopped him for a safety inspection near the White­stone Bridge on Wednesday.

He admitted he had the guns, prompting a call to the NYPD’s Harbor Unit. Police seized a revolver, rifle and two shotguns from the safe.