If there’s one piece of safety equipment on your boat that rivals a life jacket in terms of being valuable for you (and your guests) in an emergency, it’s your VHF marine radio (either handheld or fixed-mount). When you’re out of cell phone service coverage (or the battery’s dead or you left it on your charger at home), your VHF radio can summon the help you need in the case of an accident. Certain frequencies, such as channels 9 and 16, are monitored by the Coast Guard (or other boating law enforcement agency) and, when used properly, a marine radio can be an effective way to communicate with other vessels, along with harbormasters and marinas, for various reasons.
READ THE REST OF PROPER USE
http://boatingblog.discoverboating.com/ckourtakis/archive/2011/09/23/proper-use-of-a-vhf-marine-radio.aspx#.TpxBDu3S52k.facebook