When a watch is required on 2182 kHz, at how many minutes past the hour must a 3 minute silent period be observed?

The correct answer is based on maritime communication protocols, particularly concerning the use of the distress frequency 2182 kHz. When a watch must be kept on this frequency, the regulations specify that operators should observe a three-minute silent period at specific times to ensure that the channel is available for emergency communications.

The established practice dictates that these silent periods occur at 00 and 30 minutes past the hour. During these times, radio operators are required to refrain from using the frequency to allow for any distress calls to be made without interruption. This procedure is crucial for ensuring that emergency communications can be heard clearly, enhancing safety at sea.

In this scenario, the answer indicating 00 and 30 represents the correct times to observe the three-minute silent periods. Other options suggest different timings, which do not align with the established protocols for maritime radio communication on 2182 kHz.