RedactedNarrative: V1 was traveling South bound on the Colorado River inside Bullhead City Arizona.  The operator of the watercraft stated he struck a rock in shallow water.  the resulted in a large gash on the lower starboard side of the watercraft.  The gash was approximately 6" high and 4'' to 5'' in lenght.  It was estimated to cost $19,000 to repair the damage.  There were no injuries reported.