RedactedNarrative: UNIT 1 AND UNIT 2 WERE BOTH TRAVELING NORTH ON THE ICW IN A NO WAKE ZONE.  UNIT 2 FAILED TO COME DOWN TO IDLE SPEED.  UNIT 2 BEGAN TO ACCELERATE AND STRUCK UNIT 1 IN THE PORT SIDE STERN AND ENGINE.  UNIT 1 WAS RENDERED INOPERABLE AND THERE WERE NO INJURIES.