YMS-1-class minesweeper

The YMS-1 class of auxiliary motor minesweepers was established with the laying down of YMS-1 on 4 March 1941.

Characteristics of the class: Displacement 270 t.; Length 136'; Beam 24' 6"; Draft 8'; Speed 15 kts; Complement 32; Armament one single 3"/50 gun mount, two 20mm, two dcp; Propulsion two 440shp General Motors (Cleveland), 8-268A, 2-cycle diesel engines, two shafts.

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 YMSs 135–445, 480, and 481.

YMS-446 subclass
This subclass was also identical but had no stacks, and consisted of YMSs 446–479

BYMS
Eighty YMS minesweepers were ordered from US yards for transfer under Leand-Lease to the UK as the BYMS-class minesweeper. Another 53 built for the US Navy (hull numbers 137 to 284) were transferred as further BYMS and another 17 were delivered later.