RedactedNarrative: Operator states he had purchased this vessel four days prior to this accident. He states that he was east bound following another air boat. The air boat he was following turned north up another channel of the river. When he attempted to turn his air boat to the north it began to slide sideways striking the stump, causing his air boat to roll up on its starboard side, ejecting his passenger and himself approximately 20ft into the water. He is unsure what he hit breaking his elbow and his passengers back. He states the other air boat he was following turned around and rendered aid to him and his passenger until ems arrived and was able to transport them to the ambulance and later to the hosp. Area of the accident was approx 1.5 miles east of carpenter's bluff bridge and approx 40 feet south of the east shore and approx 20 feet north of the west shore.