Most boaters who venture out front have a VHF Radio and if it's a relatively new radio it is equipped with a RED DISTRESS button that when pushed will digitally broadcast you're position to other boaters and the Coast Guard. However, most people and this includes myself have never made the connection between the VHF and GPS. Without connecting the two devices together this feature is useless. So here's a procedure that seems pretty simple to understand.
http://www.usps.org/localusps/redwo...p_by_Step_Process_for_Installing_your_VHF.pdf
http://www.usps.org/localusps/redwo...p_by_Step_Process_for_Installing_your_VHF.pdf