When is a radio required on a boat?

A radio is required on a boat when operating in certain regulated waters, such as the open ocean or inland waterways, where communication is essential for safety. The U.S. Coast Guard mandates that vessels over 65 feet must carry a VHF radio. Additionally, it's advisable for all boats, regardless of size, to have a radio for emergency communication and navigation assistance. Always check local regulations, as requirements may vary by region.