RedactedNarrative: Boat was traveling at a slow rate of speed, estimated at between 10-15 mph with bow nose in the air, and wake behind the boat.  When operator came off throttle towards the dock, water came gushing in over the bow due to overcapacity, and what the operator described as choppy water.  Boat was carrying 20 persons, that was rated for 14 persons with a limit of 1,980 pounds.  Once the water started coming into the boat, it quickly filled and sunk.