Report details reasons why Australian WW1 submarine HMAS AE1 sank/was lost

In late December 2017 Submarine Matters reported Australian submarine HMAS AE1 had been found after 103 years, in Papua New Guinean waters, just above Australia (see map below).

At the outbreak of World War I, AE1, was part of the Australian Naval and Military Expeditionary Force sent to attack German New Guinea. AE1’s main roll was perhaps to guard against intervention of cruisers in Germany’s East Asia [Indo-Pacific] Squadron

Along with AE2, AE1 took part in the operations leading to the occupation of the German territory, including the surrender of Rabaul on 13 September 1914.

At 07:00 on 14 September, AE1 departed Blanche Bay, Rabaul, to patrol off Cape Gazelle with HMAS Parramatta. When she had not returned by 20:00 hours, several ships were dispatched to search for her. No trace of the submarine was found, and she was listed as lost with all hands. The disappearance was Australia's first major loss of World War.

Now technical reasons why AE1 was lost with all hands, have emerged. Papua New Guinea's PNG Industry News reveals, in part:

[March 14, 2018] A REPORT has detailed how the crew of Australian World War 1 submarine HMAS AE1 desperately attempted to save the vessel before it sank off the coast of the Duke of York Islands.

...AE1 suffered a catastrophic failure, the report found, identifying "a design failure, material failure, operator error or combinations thereof" as being responsible for the submarine's bow tipping forwards and down.

One of the submarine's twin props was not operating, which would've contributed to the crew's inability to slow or stop the downwards descent.

Once it began to gather speed, the sub's forward section imploded after the 100 metre mark, creating a shockwave that would have killed the crew of 35 instantly.

...the shockwave would have been like a "truck-bomb going off in the middle of the control room" and there was some comfort the men "didn't know what hit them" "...from the available evidence, it is clear that the crew met their end swiftly and did not die a slow, lingering death on the sea floor".

The submarine had its hydroplanes set to "hard to rise", which meant it was attempting to return to the surface. The report concluded this was a deliberate action. "Operated by a rack-and-pinion mechanism and designed to operate against maximum design speed, the planes could not have drifted into their current positions".

After ruling out various scenarios, the report found a "diving accident" was the most probable cause for the disaster. 

The crew had a lack of diving practice, and a mechanical defect to the starboard main engine clutch would have limited the power available to the submarine.

This provided a combination of circumstances that "would alone have been sufficient to lead to her loss", the report concluded.

In the report, Find AE1 recommends against any attempt to enter the hull as it is the crew's final resting place. It also warns that it is only a matter of time before treasure hunters and others will attempt to exploit the wreck or achieve fame by obtaining images.

Measures to prevent ships from anchoring, mooring or trawling in the area are recommended in the report, including installing a surveillance camera on nearby Mioko Island, as well as a permit system requiring permission from both Australian and Papua New Guinean authorities for any further activity involving the wreck..."  See the WHOLE PNG Industry News ARTICLE

HMAS AE1 sunk in Papua New Guinea's, Duke of York islands. (Map courtesy BBC)
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HMAS AE1 in happier days. (Painting courtesy Royal Australian Navy).

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Sensor image of AE1 on the seafloor.
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Deep water photo of AE1 on the seafloor 300m down, far deeper than its approximately 100m crush depth.  (Image courtesy the Australian Government via the BBC).
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Pete