I am a boating newbie. My boat has a VHF radio in it. I know that channel 16 is the emergency channel but this radio doesn't have "channels". How do I find channels? Is there a chart somewhere that says, for example, 144.075 is channel 16? I know from being in other boats that people often start a conversation on 16 and immediately switch to another channel. So how do I go from a number like 144.075 to a channel?