In the early hours of 1 June 2018 the container ship YM Efficiency was rolling heavily in bad weather about 30 kilometres south-east of Newcastle when 81 containers went over the side. Some broke up and their contents washed onto beaches along the coast for weeks. Most sank, intact or in pieces, into some of the most valuable fishing grounds in New South Wales.
The ship's insurers had a survey vessel on the water within three weeks, and by August it had marked 37 probable containers on the seabed. That still left more than 40 unaccounted for, and nobody could say which of the targets were containers and which were rock, debris or something else entirely. The Australian Maritime Safety Authority decided the uncertainty was not acceptable for the trawlers working that ground, and in November 2018 contracted Subsea to settle it.
Sonar first, then eyes
We began with side-scan sonar, running roughly 200 nautical miles of survey lines between Stockton Beach and Morna Point and logging about 40 targets of interest. Then came the part that cannot be done from the surface: putting a camera on every one of them.
We chartered local boats out of Nelson Bay and flew observation-class remotely operated vehicles down on fibre-optic tethers. The pilots brought each vehicle to within a few metres of a target to read the serial number on the container door and record video of its condition, in depths that reached 120 metres and with the East Australian Current doing its best to drag the tether off line.
"The next phase is to send the ROUVs down to identify what these targets are," Ed Korber explained when the contract was announced. Then we went and did it.
What we found
The first ROV campaign in early December 2018 confirmed two intact containers in about 120 metres of water, 32 kilometres east of Redhead. Operations resumed in January 2019 and found nine more. By May 2019 the picture was clear: 54 containers located and positively identified as belonging to YM Efficiency, across 578 square kilometres of searched seabed, with their positions and condition recorded for the recovery that followed. AMSA went to tender for the salvage in August 2019.
A footnote that became a headline
Three years later, surveying for lost containers further south off Wollongong, our crew found something that was very clearly not a container. That story is the discovery of the SS Nemesis.