Sydney Harbour anti-submarine boom net

[1] The boom formed part of the Sydney Harbour defences which also included artillery batteries and patrol boats.

[6][8] Material shortages, not lack of interest, prevented the completion of the boom net prior to the attack.

Surprised, Cargill reported the discovery to the nearby channel patrol boat, HMAS Yarroma.

Suspecting the object maybe a mine, and being reluctant to approach, he called HMAS Lolita from the eastern end of the boom net.

Given the location of M-14 and the adjacent Western Pile Light, he was unable to make a passing run and proceeded stern first to the submarine where he dropped a depth charge.

10:27 pm, Chuma, realising that he had been detected, detonated self-destruct charges, destroying the submarine and killing himself and his crew member.

Adjacent to the winch house stood a stone marker that had existed for 90 years prior to the boom net's construction.

The gate was opened by dragging it back to the hauling-back dolphin using winches housed on Laing Point.

The central and western sections of the boom consisted of some 49 clusters of four piles with the net, which were made of wire and interlocking steel rings about 450 millimetres (18 in) in diameter, suspended between them.