The Maritime Union of Australia has launched a petition calling for a coronial inquest into the death of a seafarer in Gladstone two years ago.
Captain Dudley Jacobs was killed when the tug Adonis capsized on June 11, 2011.
The Australian Transport Safety Bureau found the tug capsized after an operator error.
However the MUA say the investigation ignored operator Sea Swift's "total disregard for basic safety processes" and failed to hold anyone responsible for the tragedy, Daily Mercury reported.
ATSB chief commissioner Martin Dolan said his bureau could not assign blame but would pass on its work to the coroner if necessary.
The MUA said the Sea Swift tug was contracted by Bechtel when Jacobs died.
The union said it is shocked that Sea Swift still operated in the harbour and neither company had been held to account over the death.
Jason Hines, Gladstone MUA organiser, said a seafarer involved in the tragedy supported the push for an inquest.
"We've got 300 members in Gladstone alone. They all want the coroner onto this," Miners said.
"Even non-members, people who knew Dudley and were at his funeral, say it's got to happen."
"It is crystal clear to us … that we need a much more systematic, thorough investigation into the events prior to the incident and leading up to the capsizing of the Adonis," he said.
Miners said the ATSB report acknowledged alterations had been made to the tug, which may have affected its stability.
"That's clearly the fault of the operator – why haven't they been held to account?" he said.
"Captain Jacobs' family deserve better, and the people who work at Gladstone deserve to know that future working conditions will achieve the highest level of safety so this does not happen again," he said.
"What requirements did Bechtel put on Sea Swift before they awarded the contract, and what did the safety management systems and surveyor's reports find about the vessel's stability?"
A Bechtel spokesman said he could not comment on the report.
"This was a tragic incident. But we can't comment on the outcomes of the report because we weren't involved in the investigation nor mentioned in the resulting publication."