The VHF radio found aboard most vessels is, by far, one of the most important assests a boat can have. The modern VHF radio includes built in GPS and DSC allowing the operator to simply press an emergency button and have the emergency broadcast occur automatically giving the location of the vessel. Traditionally, it also has channel 16 which is used for emergency situations.
I have been a ships captain for over 20 years and it never ceases to amaze me how many mariners do not know how to use a VHF radio properly. I hear kids talking on the emergency channel, calls going out to other boaters as though the guy was a trucker on highway 95 ("breaker, breaker, hey good buddy you out there?). It must drive the Coast Guard crazy. Channel 16 is an Emergency channel!!
Then there is the issue of location. Your location in an emergency, or otherwise, is your Lat/Lon - it is not "a small island I see to my left". Or better yet, " just past that red sailboat". How the hell is the Coast Guard going to find you as your vessel is burning - looking for the smoke?
And what about calling. Mayday is only used when life is in danger. Pan, Pan, Pan is an emergency call of other nature. Read the book that came with your VHF and learn proper protocol - it may save your life.