What device can be used to notify other vessels when a man overboard is detected?

A VHF radio is an effective device for notifying other vessels when a man overboard situation is detected. This radio communication allows for immediate and clear transmission of distress signals and information regarding the incident to other nearby vessels, which is critical for coordinating a swift rescue. The VHF radio can broadcast on common emergency channels, such as Channel 16, where other boats can hear the distress call and respond accordingly.

While radar systems are useful for detecting other vessels and navigating, they are not typically used for communication about a man overboard. Signal flags can convey messages to nearby boats but are limited in visibility and can be easily misunderstood, especially in poor weather conditions. Sounding a horn is a method of alerting nearby vessels, but it does not provide specific information about the emergency, making it less effective than radio communication in this situation.