The WWII Darwin Harbour Anti-Submarine Boom Net and the Maintenance Winch

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Written by Norman Cramp, Director of Darwin Military Museum.

Leading up to the first Japanese air raids on Australian soil on 19th February 1942, the authorities thought, or knew, there would be, or was, Japanese naval activity in the vicinity of Darwin Harbour. And they thought one of main threats was from submarine attack within the harbour.

This was sound military logic and accordingly moves were made to defend the harbour and the ships therein. One of those actions was to manufacture and install an anti-submarine boom net that stretched across the harbour entrance from Dudley Point (on the Darwin side) to West Point (on the Cox Peninsula side). The Darwin anti-submarine boom net was the largest such net installed anywhere in world.

It is not clear as to when the installation of the net commenced nor when it was 100% completed, but it was fully operational by January 1942 – and a good thing it was!

The reason being that on 21st/22nd January 1942, the RAN Corvette HMAS Deloraine attacked and sunk an Imperial Japanese Navy submarine, the I-124, outside the Darwin Harbour. The I-124 was one of three (some say four) Japanese submarines laying mines off the NT and observing Allied shipping activities.

The submarine went down with all 80 hands on board and she remains in her final position at the bottom of the sea today, un-entered and effectively untouched for 76 years.

On 19th February 1942 there were 49 ships in Darwin Harbour and without the protection of the boom net, that day could have been more catastrophic than what it was. Just imagine being attacked from the air and attacked from below the sea at the same time, with limited room for your ship to manoeuvre and/or escape the harbour!

So, the boom net played a very important role in defending Darwin Harbour and in fact the net’s operating ships were the first to be attacked at 10am on the 19th. But the net needed maintenance from time-to-time and this is where the winch displayed at the Darwin Military Museum (DMM), East Point comes into its own.

The winch, shown above, was used to remove sections of the net back to shore for maintenance to below-sea material and structure.  It was vital work and the ‘clunky’ old winch performed its duty admirably throughout the war.

It is thought the net was finally removed in 1946-47, following which the winch and associated equipment were (effectively) abandoned by the Commonwealth, although it remained in situ for many years.

Following the clean-up, removal and sale of war equipment and debris in and around Darwin in the mid to late 1960s, the winch ended up in the position of the owner of the Frances Bay Shipyard. It is not known what, if any, role the winch played in Darwin after the war but it was in the shipyard in 2014 when the owner generously donated it to the DMM.

The winch was relocated to its current position within the DMM and refurbished by RAAA/DMM volunteers in 2015. In 2017 RAAA/DMM volunteers, DMM staff and members of the Australian Army’s 8/12 Field Artillery Regiment erected the weather protection structure and camouflage nets over the winch as a further step toward its ongoing preservation.

In 2018 the winch was refurbished again with financial assistance from the Australian National Maritime Museum (Sydney). The photo above shows the winch in its ‘as new’ condition in August 2018 when the ‘overhaul’ was completed. That same month, members of the Motor Vehicle Enthusiasts Club NT, donated a diesel engine to be installed on the winch so that visitors to the museum can see not only what the winch looked like, but how it was operated and powered.

Many thanks to all of those people and organisations who have given so generously of their time, effort, equipment and material to conserve and preserve this very important piece of the NT’s wartime equipment and story.