Merchant ships' radios were sealed to prevent transmissions from revealing a convoy's position. Only the escorts could use working radios, which concentrated communication in a few vessels. An armed trawler's equipment might still fail to receive a warning or instruction. The restriction protected operational security while making an already thin escort screen more vulnerable to missed messages.
Notable Point · 46:23-46:46
Radio silence complicated coastal convoy control
Sealing merchant radios protected a convoy's position but left its few escorts responsible for every radio warning and instruction.