Which of the following is not a permissible use of a radio?

Using profanity during radio communication is not permissible due to established protocols that govern maritime communication. The rules emphasize the importance of maintaining professionalism and clarity in all communications to ensure the safety of all mariners. The use of inappropriate language can cause confusion, misinterpretation, or even panic during critical situations, which could have harmful consequences.

Communicating with other vessels, sending distress messages, and reporting navigational hazards are all essential and permissible uses of radio communication. These functions are crucial for maintaining safety at sea, coordinating navigation, and providing assistance in emergency situations. The regulations and codes in place, such as the International Maritime Organization's (IMO) standards, reinforce the need for proper communication practices, which prohibit the use of language that can detract from the clarity and seriousness of messages exchanged over radio frequencies.