Espenido was not wearing a life jacket when he lost his balance and fell into the sea.
"The wire to which he had clipped his safety harness had broken. A crew member on the deck threw a lifebuoy into the water near the [man]. [He] was last seen swimming towards the lifebuoy."
An extensive search failed to find Espenido. Only a hard hat and a glove were found in the water about 30m apart.
"If the bosun had been wearing a buoyancy vest his chances of surviving would have been significantly greater," the report found.
"It also found that the wire rope to which the bosun had connected his safety harness broke because it was severely corroded and also that it had not been constructed and installed in accordance with best industry practice."
There was also no formal procedure for rigging the steps and the crew did not follow correct procedures to try to rescue Espenido.
It was the second time TAIC had identified the type of wire Espenido had clipped himself to as inadequate for ships.
If the wire's plastic coating got damaged, it was easily corroded by salt water.
"The Commission has raised this issue in a previous inquiry and made recommendations to the Director of Maritime New Zealand to address the issue," said the report.
However, no new recommendations were made from this inquiry for the Medinah as the ship's manager had already addressed safety issues.