RedactedNarrative: Operator advised he was traveling south out of Cedar Fourche when he struck an underwater obstruction and was ejected from V1. He also advised he was wearing a kill-switch but it failed to kill the motor and V1 began circling.  He was able to swim to the bank and seek help.  When he returned to the area with help, V1 was located upside down in the area.  Damage sustained to V1 included: broken trolling motor shaft, dents from the port side bow to the stern where V1 had struck several trees while circling and damage to the prop and lower unit.