RedactedNarrative: Occupants stated they were headed down stream from the city of Loudon when they struck something under the water between the third and fourth bridge support of the rail road trestle.  The boat motor stopped and would not restart.  They noticed water coming into the engine compartment.  They called 911.  Loudon City Fire transported all occupants to shore.  There were no injuries.  A passing by boat towed the damaged boat to the Loudon boat ramp were the vessel was loaded onto its trailer.  There did not appear to be any hull damage.  The lower unit and propeller sustained significant damage.  Water was leaking from behind the lower unit, the propeller was damaged, and the skeg was damaged.  The area were the incident occurred is well outside of the channel and contains underwater obstructions.