RedactedNarrative: Vessel 1 was anchored at the sand bar west of Cedar Point amusement park.  Occupant 2 observed smoke coming up the side of the vessel.  Occupant 1 went to check the engine room. Police boat observed the smoke and gave orders for both passengers to exit the vessel.  Occupant #1 boarded the police boat.  Occupant #2 boarded another small boat nearby.  While on board the police boat occupant #1 observed the smoke increase before the onboard halon system was triggered and put out the fire.  There was fire damage to the front of the port engine, melted fiberglass and damage to the batteries for the bow thruster.  Fire was determined to have originated at the battery connection for the bow thruster.