Net laying ship

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.

A net layer's primary function was to lay and maintain steel anti-torpedo or anti-submarine nets. Nets could be laid around an individual ship at anchor, or around harbors or other anchorages. Net laying was potentially dangerous work, and net laying seamen were experts at dealing with blocks, tackles, knots and splicing. As World War II progressed, net layers were pressed into a variety of additional roles including salvage, troop and cargo transport, buoy maintenance, and service as tugboats.

General characteristics (US Navy netlayers)
Displacement: 560 tons, 700 tons laden
Length: 151 ft. 8 in.
Beam: 30 ft. 6 in.
Draft: 10 ft. 6 in.
Speed: 14 knots
Propulsion: Diesel, single screw
Complement: 40
Armament: 1 x 3"/50 caliber dual purpose gun, 3 x 20mm mounts

US Navy

Net layers initially received the hull classification symbol YN (for "Yard Net Tender") but were later reclassified AN (for "Auxiliary Net Layer"). The British Admiralty knew such ships as a “boom defence vessel".

The first 32, all launched in 1940 (before the attack on Pearl Harbor), were built of steel. Due to the chronic shortage of steel during the war, the next 30 were built of wood. The last 15, laid down in 1944 and 1945, were again constructed of steel.

A total of 77 net layers of all classes served with the US Navy during the war. The vessels served in all theatres of war but particularly in the Pacific. Many of the ships were decommissioned after the war, but some continued in service for several more decades. Net layers were eventually made redundant by advances in underwater detection technology.

Net layers have two prominent steel "horns" on the bow, used in laying nets.

Gallery

Royal Navy Vessels Maintain the Boom Defence at Scapa Flow, Scotland, May 1943 A16572

The boom defence net at Scapa Flow being towed into position by two Royal Navy boom defence vessels in 1943.

The Royal Navy during the Second World War A16583

At Scapa Flow, a Royal Navy net laying vessel prepares to lay an anti-submarine net, which is 900 feet (275 metres) long, weighs over 40 Imperial tons (41 tonnes) and could be laid in 4 minutes.

The Royal Navy during the Second World War A17161

HMS Rogate, a Royal Navy "gate vessel" designed to open and close the boom and nets at Portsmouth Harbour during World War II.

HMCS Ypres E-35756

HMCS Ypres was a Battle class trawler used by the Royal Canadian Navy as a gate vessel. She was sunk in a collision with a battleship in May 1940.

USS TEREBINTH (AN-59)

The US Navy wooden Net Tender, USS Terebinth (AN-59) in wartime camouflage.

References

Ailanthus-class net laying ship

The Ailanthus class were a group of 40 wooden-hulled net laying ships of the United States Navy built during World War II as part of the huge building programs of late 1941 and early 1942 for small patrol and mine warfare vessels. Five of the class were transferred to the British Royal Navy under Lend-Lease, and another five were converted while at their shipyards into Auxiliary Fleet Tugs, the ATA-214-class.

Aloe-class net laying ship

The Aloe-class net laying ships were a class of thirty-two steel-hulled net laying ships built prior to the US entry into World War II. The lead ship, USS Aloe, was laid down in October 1940 and launched the following January; the final member, USS Yew, was launched in October 1941. They were assigned tree and plant names in alphabetical order, but eight ships (in order Cottonwood, Dogwood, Fir, Juniper, Maple, Poplar, Sycamore, and Walnut) were renamed prior to launching, producing discontinuities in the name order. These ships were originally classed as YN and numbered 1-32, but were reclassified and renumbered in 1944 as AN-6 through AN-37.

These ships had a unique appearance with a pair of "horns" jutting out from either side of the bow, each functioning as a fixed crane with a capacity of 22 short tons (20 t). They were powered by a pair of diesel engines which provided electricity for both propulsion and lifting machinery; there were also two auxiliary diesels and an evaporator for fresh water. Between the "horns" was an opening through which nets could be hauled, bridged by a catwalk.

All members of this class survived the war though USS Mahogany was caught in a typhoon in September 1945 and decommissioned the following year. Three ships were transferred to the French Navy in 1944 and another three were so transferred in the 1960s; two others went to the Turkish and Ecuadorian navies respectively. Three others were retained for various purposes, while the remainder were put into the reserve fleet shortly after the war.

Cohoes-class net laying ship

The Cohoes-class net laying ships consisted of fifteen ships built near the end of World War II for the United States Navy, the last being commissioned shortly after war's end. They were similar in appearance and construction to the predecessor Aloe class, with slight differences in dimensions and displacement. Unlike previous net-laying classes, names were taken from a variety of place names, rather than from plants. All but two were decommissioned and put into reserve by the end of 1947, but most were reactivated at various times in the early 1950s and remained active until the early 1960s, when seven were transferred through lease or sale to several foreign navies. Two were transferred to other federal agencies; two were reactivated in the late 1960s and these served into the 1970s. Some of those transferred abroad were still active as late as 2007; none were lost in action.

HMS Precept (Z266)

HMS Precept (Z266) was a net laying ship for the Royal Navy during the Second World War acquired from the United States Navy in October 1944 via Lend-Lease.

The ship was laid down as Precept (YN-79), a net tender of the Ailanthus class, on 5 August 1943 at Barbour Boat Works in New Bern, North Carolina. On 17 January 1944, while still under construction, the ship was reclassified as a net laying ship and redesignated AN-73. Precept was launched on 11 April and completed on 13 October.

After delivery to the U.S. Navy on 14 October, she was transferred to the United Kingdom under Lend-Lease the same day and commissioned into the Royal Navy as HMS Precept (Z266). Upon completion of wartime duty with the United Kingdom, she arrived at Norfolk, Virginia, on 22 October 1945, and was returned to the U.S. Navy on 4 January 1946. Struck from the Naval Vessel Register on 28 March 1946, she was transferred to the United States Maritime Commission on 21 March 1947 and sold.

HMS Precise (Z285)

HMS Precise (Z285) was a net laying ship for the Royal Navy during the Second World War acquired from the United States Navy in December 1944 via Lend-Lease.

The ship was laid down as Boxelder (YN-80), a net tender of the Ailanthus class, on 14 September 1943 at Barbour Boat Works in New Bern, North Carolina. On 17 January 1944, while still under construction, the ship was reclassified as a net laying ship and redesignated AN-74. Boxelder was launched on 20 July and completed on 19 December.

After delivery to the U.S. Navy on 21 December, she was transferred to the United Kingdom under Lend-Lease the same day and commissioned into the Royal Navy as HMS Precise (Z285). Upon completion of wartime duty with the United Kingdom, she was returned to the U.S. Navy on 14 December 1945. Struck from the Naval Vessel Register on 28 March 1946, she was transferred to the United States Maritime Commission on 10 April 1947 and sold.

HMS Prefect (Z263)

HMS Prefect (Z263) was a net laying ship for the Royal Navy during the Second World War acquired from the United States Navy in June 1944 via Lend-Lease.

The ship was laid down as Prefect (YN-88), a net tender of the Ailanthus class, on 1 April 1943 at the American Car and Foundry Co. in Wilmington, Delaware. On 17 January 1944, while still under construction, the ship was reclassified as a net laying ship and redesignated AN-75. Prefect was launched on 8 March and completed on 3 June.

After delivery to the U.S. Navy on 3 June, she was transferred to the United Kingdom under Lend-Lease the same day and commissioned into the Royal Navy as HMS Prefect (Z263). Upon completion of wartime duty with the United Kingdom, she arrived at Norfolk, Virginia, on 22 October 1945 and was returned to the U.S. Navy on 28 December 1945. Struck from the Naval Vessel Register on 28 March 1946, she was transferred 3 April 1947 to the United States Maritime Commission and sold.

HMS Preventer (Z265)

HMS Preventer (Z265) was a net laying ship for the Royal Navy during the Second World War acquired from the United States Navy in September 1944 via Lend-Lease.

The ship was laid down as Seagrape (YN-90), a net tender of the Ailanthus class, on 20 May 1943 at the American Car and Foundry Co. in Wilmington, Delaware. On 17 January 1944, while still under construction, the ship was reclassified as a net laying ship and redesignated AN-77. Seagrape was launched on 9 August and completed on 30 September.

After delivery to the U.S. Navy on 30 September, she was transferred to the United Kingdom under Lend-Lease the same day and commissioned into the Royal Navy as HMS Preventer (Z265). Upon completion of wartime duty with the United Kingdom, she was returned to the U.S. Navy on 10 January 1946. Struck from the Naval Vessel Register in March 1946, she was transferred to the United States Maritime Commission on 1 April 1947.

USS Abele

USS Abele (AN-58) was a Ailanthus-class net laying ship in the service of the United States Navy, named after Populus alba, commonly called abele, silver poplar, or white poplar.

USS Ailanthus

USS Ailanthus (AN-38/YN-57) was an Ailanthus-class net laying ship which served with the U.S. Navy in the western Pacific Ocean theatre of operations during World War II. She was assigned to serve the U.S. Pacific Fleet with her protective anti-submarine nets. While performing this service, she ran aground in Alaskan waters and was declared a total loss.

USS Cornel (AN-45)

USS Cornel (AN-45/YN-64) was an Ailanthus-class net laying ship which served with the U.S. Navy in the South Pacific Ocean theatre of operations during World War II. Her career was without major incident, and she returned home safely after the war.

USS Manchineel (AN-54)

USS Manchineel (AN-54/YN-73) was an Ailanthus-class net laying ship which served with the U.S. Navy in the South Pacific Ocean during World War II. She managed to survive the war without incident, and returned to the United States post-war for decommissioning.

USS Mango (AN-24)

USS Mango (AN-24/YN-19) was an Aloe-class net laying ship which was assigned to serve the U.S. Navy during World War II with her protective anti-submarine nets.

USS Mastic (AN-46)

USS Mastic (AN-46/YN-65) was an Ailanthus-class net laying ship which served with the U.S. Navy in the South Pacific Ocean theatre of operations during World War II. Her career was without major incident, and she returned home safely after the war.

USS Palm (AN-28)

USS Palm (AN-28/YN-23) was an Aloe-class net laying ship which was assigned to serve the U.S. Navy during World War II with her protective anti-submarine nets.

USS Salem (CM-11)

USS Salem (CM-11) was a commercial cargo ship, that served as a minelayer and then net laying ship of the United States Navy during World War II.

The ship was built in 1916 by William Cramp & Sons, Philadelphia, as SS Joseph R. Parrott; was acquired by the U.S. Navy on 8 June 1942 from the Maritime Commission; and commissioned on 9 August 1942, Lt. Comdr. Henry G. Williams in command.

USS Shakamaxon (AN-88)

USS Passaconaway (YN-114/AN-86) – sometimes called USS Skakamaxon -- was a Cohoes-class net laying ship which was assigned to protect United States Navy ships and harbors during World War II with her anti-submarine nets. Her World War II career was short due to the war coming to an end, but, post-war, she continued salvage operations, including those at Bikini Atoll, before being struck from the Navy in 1947.

USS Terebinth

USS Terebinth (AN-59) – laid down as USS Balm (YN-78) – was a Ailanthus-class net laying ship which served with the U.S. Navy during World War II. Terebinth served in the Pacific Ocean theatre of operations and was awarded a battle star for her participation in the Okinawa campaign. Post-war she was decommissioned and sold.

USS Viburnum (AN-57)

USS Viburnum (AN-57/YN-76) was a Ailanthus-class net laying ship which served with the U.S. Navy in the Pacific Ocean theatre of operations. While operating in the Caroline Islands, she was severely damaged when struck by what appeared to be a Japanese torpedo. However, she continued her work as well as she could, and, when she returned to the United States, she was considered too damaged to repair. She was sold in her damaged condition, and was eventually scrapped.

USS Whitewood (AN-63)

USS Whitewood (YN-84/AN-63/AG-129), a wooden-hulled Ailanthus-class net laying ship of the United States Navy was laid down on 24 October 1942 at Rockland, Maine, by the Snow Shipyard, Inc.; named Whitewood on 5 July 1943; re-classified a net laying ship, AN-63, on 1 January 1944; launched on 21 April 1944; sponsored by Mrs. Eben Kenney; and commissioned on 17 July 1944, Lt. John I. Beam, USNR, in command.

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