Most "calling for help" in the boating world is done over VHF radio, a line-of-sight marine system tht requires no special licensing or training like a short-wave transmitter. Emergency freqs are monitored by the authorities and they are quite useful for just exchanging routine information. Think of it as CB for boat people. Most larger boats (20' and over) have one of these. I don't know if there are small hand-helds in this format that would be practical.

For offshore, last-resort rescue purposes, the EPIRB is the way to go. If you get in deep trouble, you just press a button and it sends a squawk to a satellite with your position. The message is processed at a central clearing house and authorities in your vicinity are notified. Most blue-water offshore craft carry these.

A cell phone is probably ideal for the kind of dinghy camping I've described, even wilderness areas off US coasts are probably near a cell tower. Just dial 911 and ask for the Coasties.

As for GPS, they are wonderful, and as I mentioned, it would be irresponsible to go offshore without them. But it is essential you know rudimentary navigation techniques, too. A GPS can tell you exactly WHERE you are lost, but what you need to know is which way to point your boat to get where you want to go. For that you need a compass and a chart.