Curious divots in the seabed instigated researchers to vary from their original search grid, leading to the discovery of the SS Macumba wreck. Image credit: Marine National Facility.
Scientists on the CSIRO research vessel Investigator have solved a 74-year-old mystery in discovering the wreck of the SS Macumba, an Australian merchant ship sunk in an air raid off the Northern Territory coast on August 6, 1943.
Investigator’s multibeam sonar systems pinpointed Macumba‘s location in the Arafura Sea on October 4, locating the wreck at a depth of 40 metres.
The discovery was made while carrying out a targeted survey in the Arafura Sea off the coast of Arnhem Land, representing the end of a long search for Macumba.
Marine National Facility Voyage Manager on Investigator Hugh Barker said all on board were pleased to locate the wreck and help solve this wartime mystery.
“The search was important to everyone on board this voyage and a lot of eyes were either glued to monitors or scanning the horizon for the signs of marine life that often point to features underwater,” Hugh said.
“We discovered the wreck in the middle of the night after about 10 hours of searching, which was lucky as we only had a couple more hours available for the search.”
The survey was being conducted for the Northern Territory Government while Investigator was en route from Sydney to Broome. Such “transit voyages” ensure the Investigator is used to its fullest capacity during what would otherwise be considered down time.
RV Investigator, Australia’s purpose-built marine research vessel. Image credit: Marine National Facility.
Macumba was a 2,500 ton steel merchant ship that was sunk on 6 August 1943 when two Japanese aircraft attacked at low level and scored a direct hit on the ship’s engine room.
Three of the Macumba’s crew were killed in the attack, with one body never being recovered. Survivors from the attack were taken aboard an escort and the Macumba was left to sink.
While the location of the attack was known, no previous search had been able to discover the location of the wreck. Until now.
SS Macumba. Image credit: Marine National Facility.
The Investigator’s sonar has a swath width of up to 30 km in deep water, but much narrow at depths of the Macumba wreck. The target area spanned approximately 23 km2 and was gridded into 29 “lanes” that the ship would pass over in during the course of the 6-12 hour search. During one of the turns, researchers identified regularly spaced divots in the seabed. After consideration, they concluded they might be related to debris and requested a variation to the ship’s course, and that’s when they found it.
Once the wreck was mapped using the ships sonar systems, a specialised drop camera was then lowered into the water to photograph the site, capturing some incredible footage of the wreck and marine life around it.
“Macumba was about the same length as Investigator and it was likely that the wreck would have formed an artificial reef, providing habitat for a range of marine life,” Hugh said.
The Macumba wreck imaged by the RV Investigator’s multibeam sonar system. Image credit: Marine National Facility.
“Our drop camera even got a close-up photo of an inquisitive reef shark that seemed to be guarding the site. It was a special night for all on board and we are so pleased to find the final resting place of Macumba.”
Data collected by Investigator will now help inform a detailed wreck inspection report and future management as a protected historic shipwreck.
The search for SS Macumba was a collaborative effort between the CSIRO Marine National Facility and the Northern Territory Government.
Read more about the discovery from the scientists themselves here.
