A 50-foot boat exploded while being fueled at a Dania Beach marina Friday afternoon, killing one man and critically injuring four other men, a Broward Sheriff’s Fire Rescue official said. The blast about 4:30 p.m. at the marina at 4470 Ravenswood Road was powerful enough for it to be heard at the Rustic Inn Crabhouse that is diagonally across a canal from the marina, Battalion Chief Michael Kane said. The boat, which was delivered to the marina earlier Friday, was being prepared for an upcoming boat show and was fixed on a trailer while being fueled when a “large, intense blast” erupted, Kane said.