Certain models of Digital Selective Calling-equipped VHF radios will automatically switch from a working channel to channel 16 upon receipt of a DSC distress alert, distress alert acknowledgment and other DSC calls in which a channel number has been designated, according to a Coast Guard Safety Alert.
A navigation safety hazard may consequently occur if the radio is being used to maintain a listening watch or to communicate on the designated bridge-to-bridge radio-telephone or vessel traffic services monitoring channel.
Click here for the safety alert.
Click here for updated information including a listing of manufacturers of radios believed to be affected.

I already knew that Raymarine do this quickly would be in play.
Greets,
Team: Waterpsort4all