The pre-arranged signal to the waiting submarines was transmitted throughout the day from the E-Dienst radio station at Brugge, and the U-boat tender Arcona anchored at Emden.
O sinal pre-establecido para os submarinos en espera foi transmitida ao longo do día dende a estación de radio E-Dienst en Bruxas, e o buque Arcona ancorado en Emden.