Vessel 1 came up to dock to drop off passenger.  After dropping of passenger vessel #1 was unable to maneuver and collided with vessel #2 already tied to dock.  Continuing to operate vessel #1 went around to south side of dock and collided with vessel #3.  Upon contact I observed operator unable to safely maneuver vessel.  Operator stated it was her first time operating that particular vessel, had more horsepower than she was used to.
LAKE MOHAVE
Bullhead City, AZ             