The initial 80 ships were ordered by the U.S. Navy specifically for transfer to the United Kingdom under the Lend-Lease Programme. On transfer to Britain, BYMS-1 through BYMS-80 were assigned the British pennant numbers BYMS-2001 through BYMS-2080. Names were not assigned to the class members.
A further 53 BYMS vessels bore hull numbers from 137 to 284. These were originally built for the U.S. Navy as part of the YMS-1 class and transferred to Britain on, or shortly after, completion. On the Navy List they were designated BYMS, with their original U.S. Navy numbers. The remaining 17 BYMS vessels were delivered in a final batch.
By 1949, only 18 remained in service with the Royal Navy: BYMS-2031, 2039, 2044, 2047, 2049, 2052, 2055, 2063, 2070, 2079, 2157, 2167, 2173, 2213, 2214, 2234, 2253 and 2279.[1]
Twenty-five were transferred to the Royal Hellenic Navy between December 1943 and September 1948: Afroessa (ex-BYMS-2185, ex-YMS-185), Andromeda (ex-BYMS-2261, ex-YMS-261), Ariadne (ex-BYMS-2058, ex-BYMS-58), Aura (ex-BYMS-2054, ex-BYMS-54), Ithiki (ex-BYMS-2240, ex-YMS-240), Kalymnos (ex-BYMS-2033, ex-BYMS-33), Karteria (ex-BYMS-2065, ex-BYMS-65), Kassos (ex-BYMS-2074, ex-BYMS-74; mined 15 October 1944), Kefallinia (ex-BYMS-2171, ex-YMS-171), Kerkyra (ex-BYMS-2172, ex-YMS-172), Klio (ex-BYMS-2152, ex-BYMS-152), Kos (ex-BYMS-2191, ex-YMS-191; mined 15 October 1944), Lambadias (ex-BYMS-2182, ex-YMS-182), Lefkas (ex-BYMS-2068, ex-BYMS-68), Leros (ex-BYMS-2186, exYMS-186), Paralos (ex-BYMS-2066, ex-BYMS-66), Patmos (ex-BYMS-2229, ex-YMS-229), Paxi (ex-BYMS-2056, ex-BYMS-56), Pigassos (ex-BYMS-2221, ex-YMS-221), Prokyon (ex-BYMS-2076, ex-BYMS-76), Salaminia (ex-BYMS-2067, ex-BYMS-67), Symi (ex-BYMS-2190, ex-YMS-190), Thalia (ex-BYMS-2252, ex-YMS-252), Vegas (ex-BYMS-2078, ex-BYMS-78) and Zakynthos (ex-BYMS-2209, ex-YMS-209)[2][3]
Ten were transferred to the Royal Netherlands Navy between March 1946 and April 1947: Borndiep (ex-BYMS-2210, ex-YMS-210), Deurloo (ex-BYMS-2254, ex-YMS-254), Hollandsch Diep (ex-BYMS-2050, ex-BYMS-50), Marsdiep (ex-BYMS-2038, ex-BYMS-38), Oosterschelde (ex-BYMS-2230, ex-YMS230), Texelstroom (ex-BYMS2156, ex-YMS-156), Vliestroom (ex-BYMS-2155, ex-YMS-155), Volkerak (ex-BYMS-2188, ex-YMS-188"), Westerschelde (ex-BYMS-2046, ex-BYMS-46) and Zuiderdiep (ex-BYMS-2048, ex-BYMS-48).[4]
Five were purchased by Finland in 1948 of which four were transferred to the Finnish Navy and the remaining one was refurbished as missionary ship in 1953 and named Ebeneser. The ship sailed to Ceylon in and later on to Indonesian waters. The ship was lost in tropical storm in 1983.:[5] Purunpää, Vahterpää, Tammenpää, and Katanpää. These were previously designated BYMS-2032, BYMS-2044, BYMS-2049 and BYMS-2047.[6]