RedactedNarrative: According to the statement of the operator, he had launched his boat and was unable to get the engine to stay running.  He noticed water entering the vessel and tried to get back to the launch ramp with the trolling motor.  The vessel sank and another boater (name not available) helped him get it back to onto his trailer, but the vessel was upside down.  There was no visible damage to the bottom of the vessel, and the drain plug was missing when I arrived on scene.  The water likely entered the vessel at the drain.  There were no injuries due to this incident.  subject lost his cell phone, the trolling motor and fishing equipment when the vessel sank.  The extent of the damage to the engine and vessel is not fully known at the time of this report.