Propulsion was by plant as installed in the C-class cruisers, but to increase cruising efficiency a novel diesel-electric plant was trialled, the propellers being driven by either set of machinery through gearboxes. The diesel-electric plant was removed by 1941, along with the small diesel exhaust that had been trunked up the second funnel. "Adventure"s high topweight resulting from the mineload carried high up in her hull meant that typical cruiser type armament could not be fitted. Instead, four QF 4.7 in (120 mm) guns on high-angle mounts were carried in 'A', 'Q', 'X' and 'Y' positions, in hindsight a more useful arrangement. The anti-aircraft armament was completed by a single octuple multiple pom-pom in 'B' position (not fitted until the late 1930s) and a pair of quadruple Vickers machine guns.