RedactedNarrative: On May 20, 2018, at approximately 2100 hours a vessel was traveling from Callville Bay to Boulder Harbor.  Operator recognized that there was a sandbar outside of Callville Bay and was using an iphone map app to navigate.  Based on the app, Operator believed that he was past the sandbar and changed course southward.  The vessel then ran aground on the sandbar.  No injuries were sustained.  He tried to remove the vessel from the sandbar unsuccessfully.  The vessel was recovered the following morning by Tow Boat USA.