The shipmaster and second mate onboard a bulk carrier that collided with two tugboats in Tasmania had not undertaken required training in bridge management.
The Australian Transport Safety Bureau's final report into the January 2022 collision at Devonport notes it was "fortuitous" no one was on board the smaller boats when they sank.
The Goliath bulk carrier, operated by CSL Australia, had been attempting to berth when the incident happened.
Some 69,000 litres of diesel fuel and other oil spilled into the water but no one was hurt.
The report found the correct steering mode was not selected in the lead-up to the collision.
In addition to a lack of bridge resource management training among senior staff, it also noted the design of the ship's joystick system could be "misleading".
Both those issues have since been addressed, the report said, while a separate probe recommended TasPorts introduce new safety measures.
The transport safety bureau investigation also highlighted the way bridge systems are designed can reduce the risk of human error.
TasPorts chief executive Anthony Donald said the company would consider the report's recommendations before commenting on it in detail.
He said following the incident several safety requirements had been introduced and today the vessel could not operate without a marine pilot on board, a tug and had to use the standard vessel manoeuvring system.
The report comes two weeks after TasPorts briefly denied the Goliath access to Tasmanian waters alleging human error led to engine failure, however that was later overturned.
CSL Australia has been approached for comment.