RedactedNarrative: Operator of boat left the north public boat launch on Rock Lake and started heading south.  The boat began taking on water in the stern of the boat.  Operator of the boat turned the boat around to head back to shore when large waves began coming over the transom of the boat.  The boat capsized and ejected all eight passengers in the boat.  The boat's stern sunk to the bottom in 13 feet of water while the bow stayed above water.  Investigation determined that there was a fracture in the fiber glass near the transom that contributed to the boat taking on water.  Holes were also seen on the bottom of the boat by the Jefferson Co dive team.  Waves in the 2-3 foot range also contributed to the boat sinking.  Number of persons on capacity plate was sanded off.  Unknown what the model of the boat is.