A safety engineer discovered seven major faults on the Dreamworld Thunder River Rapids ride that claimed the lives of four people.
An inquest is examining how the ride at the Gold Coast theme park malfunctioned, causing a raft to flip in October 2016, killing four people including New Zealander Cindy Low.
Queensland Workplace Health and Safety engineer David Flatman told the inquest he had found seven significant faults - including missing conveyor belt slats, heavy corrosion, crumbling concrete and water hitting electrical equipment.
He said in his opinion, it had been unsafe to operate.
Mr Flatman compiled a report that was shown to the coroner, which found that missing slats on the conveyor belt created a large enough void for the tube on the second raft to be drawn into the gap between the head of the conveyor and the exposed rails.
The conveyor slats then bit into the tube and caused the raft to flip up and throw the passengers into the machinery, his report found.
"With these faults, the ride was unsafe to operate and a more rigourous maintenance regime should have been implemented," it said.
"Both operators failed to detect the drop in water level and to activate the emergency stop."
The report also found there were three contributing factors to the failure.
The report said the leading raft grounded on rails, which became exposed when a water pump failed.
That raft was then hit by another raft, which caught onto conveyor belt slats and flipped, throwing its passengers into the ride's machinery.
Mr Flatman also found there was a lack of adequate ride operator training.
He told the inquest: "A third ride operator or deck hand available at the time of the incident he may have been able to attend to the guests and allowed the load operator to focus solely on the operation of the ride."
The investigator was critical of the lack of engineering controls that had been built into the ride to avoid collisions.
He said ride safety relied heavily on the ride operators and the training they had received.
"Administrative controls were the primary means of avoiding raft collisions and that reliance on administrative controls is unacceptable as a means to ensure the safety of the ride," Mr Flatman said in his report.
He also pointed to four previous incidents involving rafts colliding. Three of them happened near the unloading area where the deaths occurred.
"It appears no preventative engineering control measures were implemented after the previous incident," the report said.
"There was little learning from previous incidents."
Under questioning last month, Dreamworld electrical engineering supervisor Scott Ritchie agreed there had been a "very significant breakdown of procedure" relating to the fatal accident.
Mr Ritchie told the inquest that while he was aware of one breakdown of a pump on the ride the day of the tragedy, he was not informed of a second, which had occurred less than an hour before the fatal accident.
Coroner James McDougall finished hearing his fifth week of evidence in the Dreamworld inquest yesterday afternoon.
The inquest is in its fifth week and resumes on Monday.