When you start looking into GPS units and VHF radios, I suggest getting a GPS and VHF that both support DSC. Basically, my VHF radio and GPS "talk" to one another. My VHF is always getting my position from the GPS. My VHF has a guarded button that, once pressed, sends my boat's info and current location over VHF frequencies. Any boat with the same setup will receive my transmission and my location will pop up on their GPS. Additionally, and more importantly, the Coast Guard will get my transmission and will hopefully be able to respond. For any non-boaters or people unfamiliar with VHF radios, it is simpler to explain "if something bad happens, push this button," as opposed to "tune to channel 16, find our location, etc." The DSC is more common than not; you just have to make sure both components are compatible. Once you get it, you register with the CG and get a number assigned to your boat. Then this number is programmed into your radio so that when the message is sent, your unique number is also sent. It allows the CG to know "who" they are receiving a signal from. My gear was purchased 3 years ago so the technology should be better and cheaper. My boat isn't built for big ocean by any means. That being said, if something happens to me, my fiance can push the button and hopefully help is not far away.