RedactedNarrative: DUE TO THE MECHANICAL FAILURE OF AN ENGINE FREEZE PLUG, WATER ENTERED THE PASSENGER AREA OF VESSEL 1, CAUSING IT TO FLOOD FROM THE INSIDE AND SINK. OPERATOR 1 ENTERED THE WATER WHEN VESSEL 1 SANK. THE COLD WATER INHIBITED OPERATOR 1'S ABILITY TO SWIM TO SAFETY OR TO REMAIN ON THE SURFACE WITHOUT A PERSONAL FLOATATION DEVICE. OPERATOR 1 DROWNED.