The operator was returning home from Captain's Island at low tide at approximately 20 mph. Operator was navigating through Captain's Harbor utilizing cell phone application by Navionics.  She preferred not to utilize her installed GPS because it was not user friendly.  The operator didn't see the submerged rock on the GPS.  The vessel struck a submerged object and stopped immediately. Vessel was towed to marina.
 
Note, accident occurred during ebbing tide; project low at 1923.
Greenwich                     