After the Barents Sea action, Jamaica returns home for a refit lasting from July to September. Her light anti-aircraft battery gains six powered twin 20 mm mounts along with four single weapons. The extra barrels increase the volume of close-range fire but do not solve the short range of the caliber. The 20 mm weapons are characterized as closer to a morale booster than a dependable way to stop an attacking aircraft before it releases its weapon. Anti-aircraft effectiveness therefore depends on reach as well as barrel count.
Notable Point · 23:46-24:27
Jamaica's 20 mm refit adds fire but little reach
Six powered twin 20 mm mounts increase Jamaica's close-range firepower, but the discussion stresses that effective anti-aircraft defense needs reach.