text: The Marine Accident Investigation Branch (MAIB) said it was difficult to keep the vessel Millennium Time on a steady heading before it struck a tug on the River Thames in July 2014.
  The report also said the man at the helm at the time of the crash did not hold a boatmaster's licence.
  City Cruises apologised and said passenger safety was "paramount".
  The nine injured passengers suffered cuts and bruises when the boat struck motor tug Redoubt, which was towing three barges between Blackfriars and Waterloo bridges on the Thames on 17 July 2014.
  The 69-year-old mate's employment as a helmsman was contrary to the instructions of the Millennium Time's operators, City Cruises, the report said.
  And the 58-year-old master of vessel was providing a sightseeing commentary, meaning he did not supervise the mate at the helm, the report concluded.
  The MAIB said the mate did not take immediate action to avoid the vessel's collision with Redoubt because he thought the motor tug was turning towards Millennium Time, but Millennium Time had unexpectedly steered towards the motor tug.
  The report said: "The turn was not deliberately initiated by the movement of the helm and most likely resulted from the unintended application of port rudder, and/or the influence of the effects of (an aquatic phenomenon known as) hydrodynamic interaction."
  By the time the helmsman noticed the vessel was turning the collision could not be prevented, the MAIB said.
  The report added the crew were also unaware of the number of passengers onboard - they thought they were carrying 426 people but the police counted 362.
  Both vessels were damaged and it took 32 days to repair Millennium Time's damage, which included broken windows.
  The MAIB, which made a number of safety recommendations, said City Cruises had replaced the steering systems on Millennium Time and its sister vessels.
  In a statement, City Cruises said its vessels undergo rigorous testing and the helmsman was in the process of completing his boatmaster's licence.
  Spokesman Kyle Haughton said: "The safety of our passengers and crew is paramount to us.
  "The report does not highlight one significant reason for the accident and refers to a number of contributing factors."
target: A pleasure boat involved in a crash that injured nine tourists had steering problems, a report has said.