sentences:  The third-batch S-class boats were fitted with either a Type 129AR or 138 ASDIC system and a Type 291 or 291W early-warning radar.HMS "Sahib" was a third-group S-class submarine and was ordered by the Admiralty on 23 January 1940.She was laid down in the Cammell Laird Shipyard in Birkenhead on 5 July 1940, and launched on 19 January 1942.