Thanks for helping me out. Do you recommend putting in all the channels or are some better and more active than others? Thanks Ron
The important channels, in more or less order of importance ....
16 -- 156.8MHz hailing and distress frequency. This is where mayday/distress calls start off.
Since larger boats are required to monitor this channel, it is also where one boat will call another. Then they shift to another channel.
If you listen to only 1 channel, this is the one.
21 and or 22 -- Coast Guard working frequency. (23 might also be used. 81,82,83 might also be used by CG, or more likely in most areas, the CG auxilliary. By monitoring, Channel 16, you will hear which channel the Coast Guards asks people to shift to for further work. It seems that particular Coast Guard stations going down the coast will alternate between 21 and 22, in order to reduce interference). You will also hear the CG come up on Channel 16 to announce that a "notice to mariners" or a special weather information broadcast will soon be transmitted on 21A or 22A. (The "A" just means that it is the simplex 156/157MHz channel, not the +4.6MHz higher duplex frequency). Most of what you hear on these channels will be routine, repetitive, "ops and position" reports where the various coast guard boats and helos check in with the sector every xx minutes. Personally, I have this one locked out and only go to it when I hear something on 16 that gets moved to 21 or 22.
13 navigation -- mostly larger ships figuring out how to keep from running into each other. Sometimes this freq will be very busy when the shipping lanes are fogbound.
Another frequency that is good to listen to is the working channel for your local Towboat US. They are kind of like the AAA of the seas. You should be able to find it by going to the towboat us website. In the Cape Cod/Buzzard Bay area, for example, they use Channel 18.
12 or 14 -- some areas these will be a vessel traffic control channel. Somewhat similar to the FAA air traffic control network. In very busy areas, additional freqs might be used, but 12 and 14 seem to be the main ones.
9 Hailing channel for small boats. In the Northeast US, the coast guard tries to get small boats to move over to channel 9 rather than using 16 for hailing (starting a conversation before moving to a working channel).
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If you search around, you will also find channels for various marinas, yacht clubs, etc. IIRC, 68 and 72 are popular.
Call your local harbormaster and ask him what channel he is on, and he will also be able to tell you the working channel for any local fire departments / police departments that have boats.
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All of the above is just in reference to the standard VHF marine channels. The link from W2lie gives info on a lot of other types of frequencies such the aviation freqs used by CG, and the internal communication frequencies used by the coast guard.