RedactedNarrative: Owner and Operator was operating vessel on Harpeth river between Dozier''s boat ramp and Hwy 49 bridge at 20-30 mph.  Passenger was also aboard the 18'' ft Searay. Near the rock bluff bend the vessel''s lower unit struck bottom and the lower unit was broken off from the I/O outboard drive.  Ashland city fire responded to the accident site.  No injuries sustained in the crash.  The vessel was towed to boat ramp and placed onto trailer. TWRA officer met driver at ramp and took his statement.