Ailanthus-class net laying ship

USS Cliffrose (AN-42), circa 1945.
Class overview
Builders:	Everett Pacific Shipbuilding & Drydock Co., Everett, Washington (10) Pollock-Stockton Shipbuilding Co., (10) Barbour Boat Works, New Bern, North Carolina (4) Snow Shipyards, Rockland, Maine (5) American Car and Foundry Co., St. Charles, Missouri (4) Canuelette Shipbuilding Co., Slidell, Louisiana (7)
Operators:	United States Navy (35)  Royal Navy (5)
Built:	1942–1943
In commission:	1943–1947
Completed:	40
Lost:	2
General characteristics
Type:	Net tender
Tonnage:	1,100 long tons (1,118 t) GRT
Length:	194–198 ft (59–60 m)
Beam:	34.5–37 ft (10.5–11.3 m)
Draft:	11.75–13 ft (3.58–3.96 m)
Propulsion:	Diesel-electric engines, 1 shaft, 1,500 hp (1,119 kW)
Speed:	12 knots (14 mph; 22 km/h)
Complement:	56 men
Armament:	1 × 3"/50 caliber gun 2, later 4 × single 20 mm AA

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.

Originally ordered on 30 September 1941 as Yard Net Tenders ("YN"), the first twenty ships (YN 57-76) were to be constructed for the British under Lend-Lease, while a further twenty (YN 77-96) were for the United States. However, after a major redistribution of small combatant contracts this order was cancelled. Finally in May 1942 contracts for twenty vessels were awarded, with orders for YN 57-66 going to the Everett Pacific Shipbuilding & Drydock Company of Everett, Washington, and for YN 67-76 to the Pollock-Stockton Shipbuilding Company of .

In July, 14 more ships were ordered from four shipyards; four (YN 77-80) from the Barbour Boat Works in New Bern, North Carolina, five (YN 81-84 and 86) from Snow Shipyards Inc. in Rockland, Maine, one (YN-85) from the Canuelette Shipbuilding Company of Slidell, Louisiana, and four (YN 87-90) from the American Car and Foundry Company of St. Charles, Missouri.

Finally, in September, the final batch of six ships (YN 91-96) were ordered from the Canuelette Company. On 19 February 1943, after a review of requirements, the first twenty ships were reallocated to the United States. In January 1944 the ships were reclassified as Auxiliary Net Layers, redesignated "AN" and renumbered. Ultimately the British allocation was reduced to five vessels (AN 73-77), and in British service they were called Boom Defence Vessels. On 9 August 1944 five of the ships that were still at their yards were ordered to be converted to Auxiliary Fleet Tugs, and AN-64, 65, and 70-72 were reclassified as ATA 214-218 on 12 August 1944.