Nick Milligan, 51, managing director of, Sky Media, was declared dead at the scene in Padstow, Cornwall, along with his daughter, Emily, eight, following the incident on 5 May.
His wife, Victoria, 39, and the couple’s other children Amber, 12, Olivia, ten, and Kit, four, were also injured by the speedboat as it circled at high speed.
The Marine Accident Investigation Branch (MAIB), report published today states: “The [boat] was fitted with a kill cord, but this was not attached to the driver at the time of the accident.
“Consequently, when the driver was ejected from the boat, the kill cord did not operate to stop the engine and the [boat] continued to out of control.”
It has not been confirmed who was driving the boat.