The Transport Accident Investigation Commission says a rusty wire was to blame for the death of a crew member on a cruise ship docked in Lyttelton.
Two crew were working on a lifeboat on the side of the cruise ship Volendam in January this year when the wire holding it snapped and both men fell into the sea.
One was rescued but the other drowned.
The commission says the wire was heavily corroded and safety lines connecting the crew to the ship were not strong enough to stop the men falling.
It says 10 other wires on the ship were also corroded.
The commission has sent an urgent notice to other ships using the same system to check their wires.
