The Fairmile B's nominal armament grew during the war, but photographs and crew stories reveal a still wider assortment of pom-poms, Oerlikons, and other acquired guns. Weapons circulated informally among merchant ships, ports, and coastal craft, with crews fitting whatever useful cannon and ammunition they could sustain. That improvisation did not erase the boat's anti-submarine purpose: an Asdic contact flag and depth charges marked a craft that often hunted in groups. A surfaced submarine might possess a deck gun, but damage from several fast, heavily armed launches could prevent it from diving again.
Chapter · 47:43-53:50
Fairmile B improvised armament and submarine hunting
Fairmile B crews treated the official weapons list as a baseline, circulating and adapting guns while retaining a dangerous pack-hunting anti-submarine role.