by Scott Wilson
Guarding One-Six
Nov 9 2009 in On the Rocks by Scott Wilson
Few things come to grate as much on cruiser’s nerves as listening to the incessant chatter on the international VHF hailing and distress frequency, 156.800 Mhz on your FM dial, or channel 16 on marine VHF sets. In many parts of the world, the frequency is used and abused to capacity, with transmissions by users expert and amateur alike crowding it during daylight hours and often well into the evening.
You are forced to endure this by law and custom if you can stand to have the radio on at all; FCC regulations require any vessel with a VHF set turned on (and vessels over 20 meters, or those in commercial use, must leave their VHF on) and not otherwise in use to monitor (or “guard” in radio parlance) channel 16. The reason for this is simple; it dramatically expands the number of stations and coverage to pick up distress calls, VHF being a relatively localized (within line of site, give or take, which generally isn’t over 40 miles at any point on the gentle curve of the ocean) technology. Moreover, since everyone is required to be on the channel, its secondary use as a hailing frequency is almost a given. If you want to contact someone, or vice versa, you know where they will be listening.
The problem generally arises with users forgetting that the channel is only supposed to be used for making initial contact, or for emergencies. Rather than making contact and then switching to a less populated frequency (since 16 is a simplex frequency; only one station can understandably transmit across it at a given time, crowding out anyone else who may need it) they will carry on their extended conversations there, subjecting the rest of us to generally boring drivel and blocking others trying to make contact… or, god forbid, who need help in an actual emergency.
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That’s a good point about DSC. We haven’t seen a huge benefit to upgrading to a DSC-capable set yet, for many of the reasons you mention.
You’re also correct about the receiving capabilities of VHF, of course; that was what I was getting at but looking back it’s quite poorly worded. Thanks for helping to clear that up for people!
As more and more boats get DSC capable radios, hopefully we will begin using it to call boat to boat and avoid cluttering up 16. DSC is not easy, unfortunately. Making a call involves several steps, and knowing the other boat’s MMSI, for which there is no directory. Given the architecture of most VHF’s and the difficulty of inputting the MMSI and connecting to a GPS, we are probably years from universal application.
Comment: just because 16 is a simplex channel is not the reason that it won’t carry multiple calls, it is that the receiver can’t sort out the calls and will only deliver the strongest signal. A duplex channel, such as the old marine operator channels, uses different frequencies for calling and receiving, and still has the same problems.