RedactedNarrative: Operator1 advised that he and Operator2 were alone on their respective PWC's traveling side by side at approximately 45 mph. Operator2 was about 10ft to Operator1's port side and approximately 20 ft ahead of him. Operator1 stated that Operator2 made a sudden hard left turn and was thrown off the rear of his PWC into the path of Operator1's vessel. Operator1 advised he was unable to avoid Operator2 and ran over him. Operator2 was recovered from the water unconscious and bleeding from a head injury.