46 CFR § 122.410 - Watchmen.
(a) The owner, charterer, master, or managing operator of a vessel carrying overnight passengers shall have a suitable number of watchmen patrol throughout the vessel during the nighttime, whether or not the vessel is underway, to guard against, and give alarm in case of, a fire, a man overboard, or other dangerous situation.
(b) Vessels described by 46 CFR 114.110(f) must submit plans to the cognizant OCMI, in accordance with 46 CFR 115.700, for the installation and use of monitoring device(s) to ensure the wakefulness of the watchmen required in paragraph (a) of this section. Vessels with a keel laid date after March 28, 2022, must include plans for the monitoring device(s) within the plan submissions required in 46 CFR 116.202. The Coast Guard will work with the vessel operators to determine a reasonable implementation schedule once the plans are accepted. The monitoring device(s) must:
(1) Ensure the wakefulness of the crew in the event that the watchman required in paragraph (a) of this section is unresponsive;
(2) Remain operable during the nighttime watch; and
(3) Be arranged to ensure proper coverage of the passenger accommodation spaces, common areas, and spaces with potential fire hazards.