The ''YMS-1'' class of

auxiliary motor minesweepers Auxiliary motor minesweepers were small wood-hulled minesweepers commissioned by the United States Navy for service during World War II. The vessels were numbered, but unnamed. The auxiliary motor minesweepers were originally designated yard min ...

was established with the laying down of ''YMS-1'' on 4 March 1941. Some were later transferred to the United Kingdom as part of the

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

Lend-Lease Lend-Lease, formally the Lend-Lease Act and introduced as An Act to Promote the Defense of the United States (),3,000 Hurricanes and >4,000 other aircraft) * 28 naval vessels: ** 1 Battleship. (HMS Royal Sovereign (05), HMS Royal Sovereign) * ...

pact between the two nations. One ship eventually made its way into the

Royal Canadian Navy The Royal Canadian Navy (RCN; , ''MRC'') is the Navy, naval force of Canada. The navy is one of three environmental commands within the Canadian Armed Forces. As of February 2024, the RCN operates 12 s, 12 s, 4 s, 4 s, 8 s, and several auxiliary ...

postwar.

Design

The design for the class had a displacement of 270 tonnes. The ships had a length of , a beam of , and a

draft Draft, the draft, or draught may refer to: Watercraft dimensions * Draft (hull), the distance from waterline to keel of a vessel * Draft (sail), degree of curvature in a sail * Air draft, distance from waterline to the highest point on a v ...

of . The vessels were capable of , being powered by two

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(Cleveland) 8-268A, 2-cycle

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which drove two shafts. The ships had a complement of 32. Their armament comprised one single 3-inch/50 caliber gun mount, two 20 mm

anti-aircraft Anti-aircraft warfare (AAW) is the counter to aerial warfare and includes "all measures designed to nullify or reduce the effectiveness of hostile air action".AAP-6 It encompasses surface-based, subsurface ( submarine-launched), and air-ba ...

guns and two depth charge projectors. ''YMS-1''-class ships were relatively small compared to larger contemporary

US Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

ships. This led to a view by some sailors that the YMS-designated ships were cramped and particularly unsteady. These conditions were described (and surely exaggerated) by one author in a humorous poem "warning" other sailors to not transfer:

Subclasses

There were two mostly cosmetic sub-types of the class, sometimes referred to as classes themselves

''YMS-135'' subclass

This subclass was identical but had only one stack rather than two, and consisted of hull numbers ''YMS-135'' through ''-445'', ''YMS-480'', and ''YMS-481''.

''YMS-446'' subclass

This subclass was also identical but had no stacks, and comprised ''YMS 446''–''YMS 479''.

BYMS

Eighty vessels of the class were ordered from US yards for transfer under

to the United Kingdom as the BYMS-class minesweeper. Another 53 built for the US Navy (with hull numbers between ''YMS-137'' and ''-284'') were transferred as further BYMS and another 17 were delivered later.

Other exports

France received 31 YMS-class minesweepers during World War 2, with one (''D202'', formerly ) being sunk by a mine in 1944. France kept its YMS-class ships in service after the end of the war,Masson 1969, pp. 59, 61–53. with seven remaining in service in 1962, used as training ships in the

École Navale École or Ecole may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * Éco ...

and as experimental vessels. Three ships of the class were transferred from France to

South Vietnam South Vietnam, officially the Republic of Vietnam (RVN; , VNCH), was a country in Southeast Asia that existed from 1955 to 1975. It first garnered Diplomatic recognition, international recognition in 1949 as the State of Vietnam within the ...

in 1954, while another was transferred to

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in 1961.Blackman 1962, p. 94. In 1947, Poland acquired former BYMS-2211 (renamed ORP Delfin), BYMS-2257 (renamed ORP Foka), and BYMS-2282 (renamed ORP Mors). The vessels were re-armed with Soviet

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and four Soviet NSV machine guns. In the mid-1950s, they were removed from service. The ORP Delfin was scuttled in the Bay of Puck, where it remains a diving attraction. The

Japan Maritime Self-Defense Force The , abbreviated , also simply known as the Japanese Navy, is the maritime warfare branch of the Japan Self-Defense Forces, tasked with the naval defense of Japan. The JMSDF was formed following the dissolution of the Imperial Japanese Navy ( ...

received 8 vessels of this class in the 1950s. The class was named ''Ujishima''-class minesweeper. The ships were: * JDS Ujishima (MSC-655) * JDS Etajima (MSC-656) * JDS Nuwajima (MSC-657) * JDS Yakushima (MSC-658) * JDS Ogishima (MSC-659) * JDS Yugeshima (MSC-660) * JDS Yurishima (MSC-661) * JDS Ninoshima (MSC-662)