47 C.F.R. § 80.301 Watch requirements.
Title 47 - Telecommunication
(a) Each public coast station licensed to operate in the band 1605–3500 kHz must monitor such frequency(s) as are used for working or, at the licensee's discretion, maintain a watch on 2182 kHz. (b) Except for distress, urgency or safety messages, coast stations must not transmit on 2182 kHz during the silence periods for three minutes twice each hour beginning at x h.00 and x h.30 Coordinated Universal Time (UTC). (c) Each public coast station must provide assistance for distress communications when requested by the Coast Guard. [51 FR 31213, Sept. 2, 1986, as amended at 69 FR 64673, Nov. 8, 2004]
Title 47: Telecommunication
PART 80—STATIONS IN THE MARITIME SERVICES
Subpart G—Safety Watch Requirements and Procedures
Coast Station Safety Watches
§ 80.301 Watch requirements.

