In 1914, the first task of the newly formed Royal Australian Navy following the August declaration of World War I was to seize or neutralise German territories in the Pacific. The British-built AE1 submarine with an Australian and British crew of 35 was part of that small fleet.

But it was quickly to become the nation's first naval loss of the war on September 14 when she disappeared off the Duke of York Islands in Papua New Guinea. She was intending to make way to Rabaul harbour for resupply and repairs, however she vanished without trace and, despite numerous searches, has never been found.

This week the mine hunter HMAS Yarra will search the volcanic waters of the area with a group of descendants waiting in Rabaul and some on board joining a wreath-laying ceremony at sea in the hope that the questions about what happened to the vessel will now be solved.

At a commemorative service for the submarine in England in May, Prince William told Vera Ryan of the AE1 Descendant Families' Association that it would be good for families to finally have some answers.

She lost her uncle, Jack Messenger, and now his great nephew David Messenger will be among the handful of relatives travelling to PNG this week.

Messenger told The Sun-Herald he had served in the navy in a similar role to his ancestor but had never wanted to be a submariner.

"It will be very hard to find, there are so many places it could be," he said. "My guess is that they had a malfunction."

The malfunction theory is supported by the diary of a WW1 naval wireless telegraph operator included in the exhibition War at Sea – the Navy in WWI, which opens on Thursday at the Australian National Maritime Museum.

John Brown was in the gunboat HMAS Protector, which was in nearby waters when the AE1 disappeared. Even while they were still in Sydney, he wrote: "The submarines go to sea every day for a dip. There is something wrong with the port engine of AE1, it fails nearly every time they want to use it. Something will happen to her one of these days."

Four days after she disappeared, he wrote on September 18 that HMAS Parramatta contacted the submarine.

"AE1 replied, 'I have had trouble with the port engine but it is now all right. Everything is all right, I am going to dive.' A.E.1. dived & was never seen again. On returning to Rabaul A.E.11 [the sister submarine AE2 ] reported that an explosion had been heard while she was submerged."

Curator of the exhibition Stephen Gapps questioned whether the wireless operator had actually heard that conversation given that most communication was likely to have been by visible means with wireless still in its infancy. "It is tantalising to think that the submarine is still in one piece but it would depend on how it went down," he said.

The search:

• HMAS Yarra will search using sonar that operates beyond 500 metres
• The variable depth sonar fitted to the Huon class ship is designed for mine hunting and is traditionally operated in shallower waters.
• A century in the volcanic waters may mean the AE1 is obscured by metres of volcanic deposits.