RedactedNarrative: Vessel1 traveling southbound, was approaching the dock at the Kiowa 2 boat ramp to drop off  Passenger 5.  Victim1  had been riding on a "Jet Ski Trainer" air up device being towed behind Vessel1.  Victim1 was still aboard the air up device that had been pulled up to the swim deck, remaining partially in the water.  When operator of Vessel1 placed the vessel in reverse to slow while approaching the dock, Victim1 was apparently knocked off into the water.  Victim1 was then swept underneath the vessel and was struck by the prop.  Victim1 became entangled in the prop and was freed by passenger2.