I had to tune to the .25 kHz offset to hear both stations correctly, so it does not seem to be a case of one radio being off?
Nothing heard today at all, I was recording both 60m and 49m. Maybe they took the day off. Or there are some other frequencies we don't know about.
I have a suspicion about how they get in touch with each other. I *think* each guy listens to a particular frequency, and if anyone wants to talk to him, they call him there. Not 100% sure yet, but it seems that way.
That makes sense...especially if they’re running more than one HF radio in the wheelhouse, with the secondary radio standing by on “their” channel...probably with the squelch turned up just a little bit. Wanna talk to Captain X? Tune to channel/frequency X at a certain time and whistle into the mic / call the guy’s name etc.
There are probably dozens of these “side channels” or “sidebands” in use, if this is the operating procedure. Considering the memory capacity of modern HF SSB marine radios, it could be easily done.
I still think at least some of these guys are using HF for quasi-NVIS types of communications. The VHF marine band is busy in all of these coastal New England towns too. I imagine the idea of having a “private channel” for general chit chat is quite appealing to these ship captains.
When I was in Portland, Maine and Gloucester, Mass. last month it was readily apparent that the vast majority of fishing vessels had multiple MF/HF antennas and often 4-5 VHF antennas. The nicer looking ones had what appeared to be SATCOM antennas as well. Fishery company buildings on both the Portland and Gloucester waterfronts sported VHF base station antennas and HF dipoles on their roofs. I bet the captains like being able to talk to each other without too much risk of the boss-man or other boats listening to their QSO.
Considering how active the regular VHF marine channels were in Portland, and the lobsterboat captain’s remarks about captains scanning the VHF channels to listen to their competitors’ radio chatter....Chris’ theory makes even more sense.
Practical VHF marine range is limited by antenna height, but it seems like most captains use a practical limit of 15-20 miles for most applications. A 100-150 watt HF radio should provide better ground wave range than a 25 watt VHF marine radio, and the use of out-of-band frequencies means your boss/competition would have to do some serious signals intelligence work (own a SDR, general coverage receiver, shortwave receiver with SSB, etc.) to find your “secret channel” or “sideband”.
I do love the mystery of these quasi-legal or straight up freebanding two-way SSB HF users.