RedactedNarrative: Vessel was floating down the river and facing backwards compared to the direction of the river flow.  Vessel approached the Railroad Bridge posts west of Commercial St in Menasha.  The operator attempted to turn the vessel downstream, at that same time the passenger stood up as the operator was maneuvering the vessel around and the vessel began to tip downstream.  The vessel then capsized and both the operator and passenger fell out of the boat.  The passenger swam to the shore and the operator held onto the upside down vessel and waited for help.