Under the heading of "Radio Watchkeeping Regulations" they tell readers to jump to another page specifically for radio watchkeeping at
However, further down the general information page under the heading "Boat Calling Channel", the U.S. Coast Guard says:
...FCC regulations require boaters having VHF radios to maintain a watch on either VHF channel 9 or channel 16, whenever the radio is turned on and not communicating with another station.
Since the Coast Guard generally does not have the capability of announcing an urgent marine information broadcast or weather warning on channel 9, use of channel 9 is optional.
Unfortunately no cite of an actual federal regulation is given.
The USCG NavCen page on Radio Watchkeeping Regulations refers to two sections of federal regulations. The first of these is in regard to vessels that are compelled to carry a VHF Marine Band radio:
§ 80.148 Watch on 156.8 MHz (Channel 16).
Each compulsory vessel, while underway, must maintain a watch...
Since recreational boat are not required to carry a radio, those regulations are not applicable, so I won't quote them here.
Another section of federal regulations is also mentioned in the U.S. Coast Guard page on watchkeeping, 47CFR80.310. These regulations appear under the heading "Subpart G - Safety Watch Requirements and Procedures." This suggests these regulations are distinct from an earlier subpart titled "Subpart C - Operating Requirements and Procedures." That is, they are special safety watch procedures.
§ 80.310 Watch required by voluntary vessels.
Voluntary vessels not equipped with DSC must maintain a watch on 2182 kHz and on 156.800 MHz (Channel 16) whenever the vessel is underway and the radio is not being used to communicate. Noncommercial vessels, such as recreational boats, may alternatively maintain a watch on 156.450 MHz (Channel 9) in lieu of VHF Channel 16 for call and reply purposes. Voluntary vessels equipped with VHF-DSC equipment must maintain a watch on 2182 kHz and on either 156.525 MHz (Channel 70) or VHF Channel 16 aurally whenever the vessel is underway and the radio is not being used to communicate. Voluntary vessels equipped with MF-HF DSC equipment must have the radio turned on and set to an appropriate DSC distress calling channel or one of the radiotelephone distress channels whenever the vessel is underway and the radio is not being used to communicate. Voluntary vessels equipped with a GMDSS-approved Inmarsat system must have the unit turned on and set to receive calls whenever the vessel is underway and the radio is not being used to communicate.
The first element of this federal regulation that raises a question for me is the requirement to maintain a watch on 2182-kHz. The U.S. Coast Guard announced several years ago that they, themselves, no longer maintain a watch on that frequency.
In regard to non-commercial voluntarily-radio-equipped boats, the regulation says:
Noncommercial vessels, such as recreational boats, may alternatively maintain a watch on 156.450 MHz (Channel 9) in lieu of VHF Channel 16 for call and reply purposes.
The curious part of this regulation is that is use of the qualifiers "may", "alternatively", and "for call and reply purposes." This regulation in under the subpart on "Safety Watch Procedures" yet it talks about "call and reply purposes."
I read the quoted regulation above as saying as the radio watch on Channel 09 is only for call and reply purposes as an alternative to using Channel 16 for that purpose, and a recreational boat may use it for that purpose. Even the U.S. Coast Guard advises recreational boaters to use Channel 16 as their radio watch:
We recommend boaters normally keep tuned to and use channel 16 in those waters unless otherwise notified by the Coast Guard.
(There is no preceding explanation for "those water" so I have no idea where "those waters" might be located.)
But I don't see where there is a relief of the boat's obligation to maintain a watch on Channel 16 for distress calls. Channel 16 is the international distress frequency. How would keeping a watch on Channel 09 and abandoning a watch on Channel 16 contribute to the general purpose of the required watchstanding: improving boater safety by increasing the number of radios listening to the recognized distress channel. My understanding of USCG radio procedures is they DO NOT maintain any radio watch on Channel 09--it is not a distress channel.
A "voluntary ship" is defined at 47 CFR 80.5:
Voluntary ship. Any ship which is not required by treaty or statute to be equipped with radiotelecommunication equipment.