What should boaters do if they experience a life-threatening emergency and need to communicate via VHF radio?

In a life-threatening emergency while boating, issuing a MAYDAY call on Channel 16 is the appropriate and most effective action to take. Channel 16 is the designated hailing and distress frequency for VHF radios, which means that all vessels and coastal radio stations monitor this channel for emergency communications. By calling out a MAYDAY, the boater immediately informs all nearby vessels and rescue organizations that they are in a critical situation requiring urgent assistance. The clarity and urgency of a MAYDAY call ensure that help is dispatched as quickly as possible.

The other options do not provide the necessary urgency or intent required in an emergency. Using Channel 68 is not appropriate for distress calls, as it is not the designated safety channel. Remaining silent could lead to delays in response and might prevent rescuers from knowing where help is needed. While using a mobile phone could be an alternative in some scenarios, VHF radios are typically more effective for marine emergencies due to their reliability and the fact that they broadcast to a wider audience, ensuring faster assistance. Therefore, the best course of action in a life-threatening situation is to issue a MAYDAY call on Channel 16.