RedactedNarrative: Operator traveled to end of the canal where they dropped anchor and began to fish.  After about 15 minutes they noticed the vessel was taking on water.  He tried to start the motor in order to get underway and allow the water to drain but the motor wouldn't start.  He directed some passengers to the port side to stabilized the boat.  They attempted to pull the anchor but the vessel flipped over causing all 6 occupants to be thrown in water.  Only person wearing a pfd was a male.  They were in the water about 10 minutes before they were rescued by Harbormaster and brought to shore.  Operator/owner was injured.  According to Tow Boat USA operator the hatch in the motor mount area may have been not been secured properly or the hatch seal was bad and may have caused it to fill with water.  Investigator concluded possible causes as the hatch/seal was not properly sealed or seal failure causing the vessel to take on water.  The vessel was overloaded and may have exceeded the weight limit.  The vessel may have been anchored from the stern.