RedactedNarrative: UNIT 1 WAS RETURNING TO THE DOCK ON THE NIGHT OF 10/13/2018.  AS UNIT 1 BEGAN TO THROTTLE DOWN HEADING TOWARDS THE DOCK, UNIT 1 COLLIDED WITH UNIT 2 AT APPROXIMATELY 10-15 MPH.  UNIT 2 DID NOT HAVE ANY NAVIGATION LIGHTS ON AT THE TIME OF THE INCIDENT.  UNIT 1 OPERATOR SUSTAINED BROKEN RIBS AND CLAVICLE AS A RESULT OF THE COLLISION.