VICTIM was being towed on tube behind boat with teenage daughter also on tube.  VICTIM had reportedly been consuming alcohol and was impaired.  VICTIM also had a history of knee problems.  At some point while being towed at an estimated 15mph, VICTIM''s left knee became dislocated.  It was indicated by several people on board the vessel that it has been dislocated before.  The operator of the vessel was not found to have acted negliently or dangerlously.
Bullhead City, AZ