RedactedNarrative: V1 traveling north between spoil islands and west side of Island of Palm Beach with two occupants (including operator).  Operator turned sharply to west to enter channel to ICW and ejected himself and other occupant.  V1 started doing circles with no one on board.  Passenger swam for nearest dock.  Operator attempted to reboard vessel and was struck by V1 and prop twice.  Operator then swam to dock to await EMS.  V1 continued in circles until grounding in mangroves.  Operator injuries were broken femur and deep lacerations to both legs.