in the fall hunting guide, page 35, spring turkey hunting, it states under prohibited acts 'turkeys may not be shot or stalked from a boat in Dyer, Haywood, Lauderdale, Shelby or Tipton counties. "
If you have permission to hunt the property next to the water, it would be legal to shoot a turkey (with the exception of the WTN counties where turkey can't be taken from a boat) as long as the boat has no forward motion from any mechanical means including a trolling motor or sail.
However, floating a river and shooting turkeys where you don't have permission to hunt is 100% illegal.