The mate on a tug involved in the fatal duck boat crash in Philadelphia last July was dealing with a family crisis by cell phone at the time of the accident, according to reports from the National Transportation Safety Board (NTSB). The mate, 34, who has invoked his Fifth Amendment right to remain silent, told a member of K-Sea Transportation Partners’ senior management that while on watch he found out about a “life-threatening emergency” involving his son, according to the documents. He had not told anyone else in the crew, and “the mate did not delegate any responsibility for maintaining a lookout to either deckhand No. 2 or the engineer,” the NTSB said. The disabled tour boat sank in the Delaware River after its stern was struck by the bow of the city’s 250’ sludge barge being towed by K-Sea’s 2,400-hp tug Caribbean Sea, according to NTSB’s earlier report. Two people died and 10 were injured after the disabled tour boat sank.