Unit 1 was heading up river at an estimated speed of 1-9 mph. Unit 2 was heading up river in the same direction as unit 1. Unit 2 was crsuising at an estimated speed 40 miles per hour or above. Unit 2 struck unit 1 in the stern of the boat. Unit 2 struck unit 1 in the motor and starboard stern and pulled to the starboard side of the vessel. Unit 1 passenger 1  received laceration to her head and was treated by EMS. Unit 2 operator received a laceration to his upper arm and was also treated by EMS. There was extensive damage to unit 1 vessel. The operator seat was detached from the pedestal , seats in the stern were ripped off, pontoons were damaged canopy was detached and in the water. Several items such as tackle boxes , fishing rods, water skis, wake boards, and floats were in the water. Unit 2 operator stated that he knew the river well and was pretty much wide open on the throttle. Unit 2 operator stated he did not see Unit 1. Unit 1 operator and passengers were interviewed amd gave statements. Unit 1 operator and passengers stated the navigation lights were on and in working order. There were two seperate persons who witrnesses the accident. The witnesses said that Unit 1 lights were on and in working order. Unit 2 operator was charged with negligent operation. Unit 2 operator was given a field sobriety test for alcohol. Unit 2 operator completed the test satisfactorily. The charge is still pending at this time.