BOSTON — A Massachusetts man has pleaded guilty to making hoax radio distress calls to the Coast Guard that prompted fruitless searches that wasted time and resources.Prosecutors say 47-year-old Roger Martin, of Fairhaven, made three calls to the Coast Guard in April and May 2015 claiming that he was on a boat on Cape Cod Canal that was sinking.In each case he provided another man's name, address, and on one occasion, even birth date, that he had obtained improperly from a law enforcement database while working as a dispatcher for the Bristol County Sheriff's Office.