Using a Marine VHF radio?
Marine VHF radios are used to contact other ships, locks, traffic-posts, other shore stations or the coast-guard, both at sea and on inland water. It ensures you know what is happening in your direct surrounding and enables you to map out a safe course.
You can use the Marine VHF radio to remain in contact with traffic supervisors and you will receive safety messages while on board. Your emergency call will be heard by anyone listening to their own Marine VHF radio.
Having the device on board of a small vessel is not mandatory (with a few exceptions), but it is essential in areas of commercial sailing.