The Sydney Harbour anti-submarine boom net was an anti-torpedo and submarine defence net that was in Sydney Harbour during World War II. It spanned the entire width of the harbour from Laing Point (formerly known as Green Point), Watsons Bay to Georges Head, on the northern side of Sydney Harbour. [1] The boom formed part of the Sydney Harbour defences which also included artillery batteries and patrol boats. [2]
Construction of the boom commenced in January 1942 and the boom and gates were fully operational by August 1942. For over three years, entry to Sydney Harbour was restricted by the boom net. All vessels including ships, ferries and fishing boats gained access to the harbour via one of three gates in the anti-torpedo and anti–submarine boom which spanned the harbour from Green Point to Georges Head. [4]
On the night of 31 May 1942, three Japanese midget submarines entered the harbour in what became known as the Battle of Sydney Harbour [5] (often referred to as the Attack on Sydney Harbour). [6] [7] On the night of the attack the central section of the net was complete and support piles were in place to the west, but there were gaps of up to 400 metres (1,300 ft) wide on either side of the boom net. [6] [8] Material shortages, not lack of interest, prevented the completion of the boom net prior to the attack. [9] The first submarine, the M-14, [5] commanded by Lieutenant Jahai Chuma, was the first submarine to attempt entry. After passing through the western gap, M-14 became entangled in the western end of the boom net's central section. Lieutenant Chuma tried to free his submarine, however, his actions entangled its twin propellers further. At approx. 8.30 pm the night watchman James Cargill, aboard the Maritime Service Board construction barge, spotted what he thought to be a fishing boat at the net and rowed across in a boat. He discovered the object to be the bow of the Japanese submarine. Surprised, Cargill reported the discovery to the nearby channel patrol boat, HMAS Yarroma. The commander of Yarroma reported the object and received instructions to investigate further. Suspecting the object maybe a mine, and being reluctant to approach, he called HMAS Lolita from the eastern end of the boom net. HMAS Lolita came across the harbour and approached the object. Those aboard Lolita confirmed the object to be a midget submarine. Realising the consequences if the submarine broke free and proceeded up the harbour, the commander of Lolita, Commissioned Warrant Officer Herbert Anderson signalled naval headquarters a submarine had been identified and he was proceeding to attack. 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. Unfortunately the depth charges had been ordered to be set to 100 feet and due to the shallow water it failed to detonate. He again manoeuvred to the submarine and dropped a second depth charge which also failed to explode. As he manoeuvred Lolita to drop a third depth charge, at approx. 10:27 pm, Chuma, realising that he had been detected, detonated self-destruct charges, destroying the submarine and killing himself and his crew member. The two other midget submarines, M-21 and M-24 successfully penetrated the partially completed boom net. M-24 fired two torpedoes at USS Chicago. Both missed with one detonating against the Garden Island sea wall destroying HMAS Kuttabul. The second ran harmlessly onto the shore at Garden Island. M-24 then escaped the harbour and was discovered in 2006 on the sea bed off Sydney's northern beaches. M-21 was sighted in Taylors Bay and subsequently destroyed by depth charges from HMAS Seamist (incorrectly referred to as HMAS Sea Mist). [5]
The boom net was removed after the end of the war in August 1945, and by early 1946, everything apart from the dolphins had been removed. The foundations of the winch house are the only remaining evidence of the anti-submarine boom net and they can still be seen on the shores of Green Point, along with other remaining evidence of military installations, such as underground fortifications and bunker complexes.
Adjacent to the winch house stood a stone marker that had existed for 90 years prior to the boom net's construction. Erected in 1850, this was used as a navigational leading mark for the Eastern Channel; it was lined up with the back mark which still stands on the west side of Parsley Bay. [10]
The western gate was usually kept shut and was only opened for very large vessels that were damaged or under tow, which required the use of the deeper and straighter Western Channel. The western gate was opened by a tug boat. All other ships used the eastern gate, which was controlled by the boom gate vessel. The gate was opened by dragging it back to the hauling-back dolphin using winches housed on Laing Point. Another gate for smaller vessels, such as Manly ferries, tugs, yachts, sailing and fishing boats, was lowered to a depth of 5 metres (16 ft) with a winch mounted on board the boom gate vessel. The boom gate vessel used to open these gates was HMAS Kuramia, a converted Sydney Harbour ferry, that had been used for public transportation from 1914.
The boom was 1,480 metres (4,860 ft) long, with two gate openings for ships. The gate on the Western Channel was 121 metres (397 ft) in length and was used for larger vessels. The gate on the eastern side of the channel (Eastern Channel) was 91 metres (299 ft) long, and, for smaller vessels, there was another gate 30 metres in length located on the western side of the boom gate vessel. 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. The eastern, Laing Point, section of the net was suspended from buoys, as were the eastern and western gate nets.
The Type A Ko-hyoteki class was a class of Japanese midget submarines (Kō-hyōteki) used during World War II. They had hull numbers but no names. For simplicity, they are most often referred to by the hull number of the mother submarine. Thus, the midget carried by I-16-class submarine was known as I-16's boat, or "I-16tou."
Port Jackson, consisting of the waters of Sydney Harbour, Middle Harbour, North Harbour and the Lane Cove and Parramatta Rivers, is the ria or natural harbour of Sydney, New South Wales, Australia. The harbour is an inlet of the Tasman Sea. It is the location of the Sydney Opera House and Sydney Harbour Bridge. The location of the first European settlement and colony on the Australian mainland, Port Jackson has continued to play a key role in the history and development of Sydney.
HMAS Adelaide was a Town-class light cruiser of the Royal Australian Navy (RAN), named after Adelaide, the capital city of South Australia. Laid down in 1915, wartime shortages and design modifications meant the ship was not completed until 1922, earning her the nickname "HMAS Longdelayed".
HMAS Onslow is one of six Oberon-class submarines, decommissioned in 1999 and previously operated by the Royal Australian Navy (RAN). The submarine was named after the town of Onslow, Western Australia, and Sir Alexander Onslow, with the boat's motto and badge derived from Onslow's family heritage. Ordered in 1963, Onslow was laid down at the end of 1967 by Scotts Shipbuilding and Engineering Company in Scotland, launched almost a year later, and commissioned into the RAN at the end of 1969.
Watsons Bay is a harbourside, eastern suburb of Sydney, in the state of New South Wales, Australia. Watsons Bay is located 11 km north-east of the Sydney central business district, in the local government area of the Municipality of Woollahra.
HMAS Kuttabul, formerly SS Kuttabul, was a Royal Australian Navy depot ship, converted from a Sydney Ferries Limited ferry.
In late May and early June 1942, during World War II, Imperial Japanese Navy submarines made a series of attacks on the Australian cities of Sydney and Newcastle. On the night of 31 May – 1 June, three Ko-hyoteki-class midget submarines, each with a two-member crew, entered Sydney Harbour, avoided the partially constructed Sydney Harbour anti-submarine boom net, and attempted to sink Allied warships. Two of the midget submarines were detected and attacked before they could engage any Allied vessels. The crew of M-14 scuttled their submarine, whilst M-21 was successfully attacked and sunk. The crew of M-21 killed themselves. These submarines were later recovered by the Allies. The third submarine attempted to torpedo the heavy cruiser USS Chicago, but instead sank the converted ferry HMAS Kuttabul, killing 21 sailors. This midget submarine's fate was unknown until 2006, when amateur scuba divers discovered the wreck off Sydney's northern beaches.
A net laying ship, also known as a net layer, net tender, gate ship or boom defence vessel was a type of small auxiliary ship.
The Lake Macquarie anti-submarine boom was a submarine and small boat defence boom located at the entrance to Lake Macquarie, New South Wales, Australia during World War II.
Fort Lytton is a heritage-listed 19th century coastal fort in the suburb of Lytton in Brisbane, Queensland, Australia. The name “Fort Lytton” is also used to describe the 1 square mile (2.6 km2) military base that surrounded the fort. Fort Lytton was built in 1880–1882, and operated until 1965. The historic fort is now contained in Fort Lytton National Park. The park is open to the public on most Sundays and public holidays. Guided tours are provided by Fort Lytton Historical Association, a non-profit volunteer organisation.
Yandra was a 990-ton coastal steamer built by Burmeister & Wain, Copenhagen in 1928 for Coast Steamships for service in the Australian state of South Australia. She was requisitioned by the Royal Australian Navy in June 1940 during World War II for conversion to a minesweeper and anti-submarine vessel and was commissioned on 22 September 1940 as HMAS Yandra. She returned to civilian service in 1946. She ran aground during dense fog onto South Neptune Island on 25 January 1959 and was subsequently written off.
HMAS Yarroma was formerly a luxury motor cruiser, commissioned as a channel patrol boat operated by the Royal Australian Navy (RAN) during the Second World War. She was one of thirteen similar vessels, known to Sydneysiders as the 'Hollywood Fleet'.
HMAS Toomaree was formerly a luxury motor cruiser, commissioned as a channel patrol boat and operated by the Royal Australian Navy (RAN) during World War II. She was one of thirteen similar vessels, known to Sydneysiders as the 'Hollywood Fleet'.
HMAS Seamist (10) was formerly a Sydney-based luxury motor cruiser, commissioned as a channel patrol boat into and operated by the Royal Australian Navy (RAN) during World War II. She was one of thirteen similar vessels, known to Sydney siders as the 'Hollywood Fleet'.
HMAS Silver Cloud (52) was a luxury motor cruiser, commissioned as a channel patrol boat operated by the Royal Australian Navy (RAN) during World War II. She was one of thirteen similar vessels, known to Sydneysiders as the 'Hollywood Fleet'.
HMAS Steady Hour (12) was formerly a luxury motor cruiser, commissioned as a channel patrol boat and operated by the Royal Australian Navy (RAN) during the Second World War. She was one of thirteen similar vessels, known to Sydney siders as the 'Hollywood Fleet'.
HMAS Marlean (Q20) was a channel patrol boat commissioned into and operated by the Royal Australian Navy (RAN) during World War II. She was one of thirteen similar vessels, known to Sydney siders as the 'Hollywood Fleet'.
HMAS Nereus (19) was formerly a luxury motor cruiser, commissioned as a channel patrol boat operated by the Royal Australian Navy (RAN) during the Second World War. She was one of thirteen similar vessels, known to Sydneysiders as the 'Hollywood Fleet'.
M24 Japanese Midget Submarine wreck site is a heritage-listed former midget submarine and now archaeological site located in unincorporated waters off Sydney's Northern Beaches in New South Wales, Australia. The Ko-hyoteki-class midget submarine was designed by the Japanese Imperial Navy and built from 1941 to 1942 by Kure Naval Yard or Ourazaki Naval Yard. The site was added to the New South Wales State Heritage Register on 7 December 2007.
HMAS Lolita (14) was formerly a luxury motor cruiser, commissioned as a channel patrol boat into and operated by the Royal Australian Navy (RAN) during World War II. She was one of thirteen similar vessels, known to Sydney siders as the 'Hollywood Fleet'.
Coordinates: 33°50′28″S151°16′36″E / 33.841076°S 151.276744°E
