(a) Title 46 U.S.C. 8104 applies to the establishment of watches aboard certain U.S. vessels. The establishment of adequate watches is the responsibility of the vessel's master. The Coast Guard interprets the term "watch" to be the direct performance of vessel operations, whether deck or engine, where such operations would routinely be controlled and performed in a scheduled and fixed rotation. The performance of maintenance or work necessary to the vessel's safe operation on a daily basis does not in itself constitute the establishment of a watch. The minimum safe manning levels specified in a vessel's COI or other safe manning document take into consideration routine maintenance requirements and ability of the crew to perform all operational evolutions, including emergencies, as well as those functions which may be assigned to persons in watches.(b) Subject to exceptions, 46 U.S.C. 8104 requires that when a master of a seagoing vessel of more than 100 GRT establishes watches for the officers, sailors, and oilers, "the personnel shall be divided, when at sea, into at least three watches and shall be kept on duty successively to perform ordinary work incidental to the operation and management of the vessel." Solely for the purposes of this part, the Coast Guard interprets "sailors" to mean those members of the deck department other than officers, whose duties involve the mechanics of conducting the ship on its voyage, such as helmsman (wheelsman), lookout, etc., and which are necessary to the maintenance of a continuous watch. The term "sailors" is not interpreted to include able seamen and ordinary seamen not performing these duties.(c)(1) Subject to exceptions, 46 U.S.C. 8104(g) permits the officers and crew members to be divided into two watches when at sea and engaged on a voyage of less than 600 miles on the following categories of vessels- (ii) Offshore supply vessels, except as provided by paragraph (c)(2) of this section; or(2) Paragraph (c)(1) of this section applies to an OSV of at least 6,000 GT ITC (500 GRT if GT ITC is not assigned), as defined in § 125.160 of this chapter, if the individuals engaged on the vessel are in compliance with the work hours and rest period requirements in § 15.1111 of this part.(d) Subject to exceptions, 46 U.S.C. 8104(h) permits a master or mate (pilot) operating a towing vessel that is at least 8 meters (26 feet) in length measured from end to end over the deck (excluding sheer) to work not more than 12 hours in a consecutive 24-hour period except in an emergency. The Coast Guard interprets this, in conjunction with other provisions of the law, to permit masters or mates (pilots) serving as operators of towing vessels that are not subject to the provisions of the Officers' Competency Certificates Convention, 1936 (see 46 U.S.C. 8304 ), to be divided into two watches regardless of the length of the voyage.(e) Fish processing vessels are subject to various provisions of 46 U.S.C. 8104 concerning watches, including- (1) For fish processing vessels that entered into service before January 1, 1988, the following watch requirements apply to the officers and deck crew:(i) If more than 5,000 GRT-three watches.(ii) If more than 1,600 GRT and not more than 5,000 GRT-two watches.(iii) If not more than 1,600 GRT-no watch division specified; or(2) For fish processing vessels that entered into service after December 31, 1987, the following watch requirements apply to the officers and deck crew: (i) If more than 5,000 GRT-three watches.(ii) If not more than 5,000 GRT and having more than 16 individuals onboard, primarily employed in the preparation of fish or fish products-two watches.(iii) If not more than 5,000 GRT and having not more than 16 individuals onboard, primarily employed in the preparation of fish or fish products-no watch division specified.(f) Properly manned uninspected passenger vessels of at least 100 GRT- (1) Which are underway for no more than 12 hours in any 24-hour period, and which are adequately moored, anchored, or otherwise secured in a harbor of safe refuge for the remainder of that 24-hour period, may operate with one navigational watch;(2) Which are underway more than 12 hours in any 24-hour period, must provide a minimum of a two-watch system;(3) In no case may the crew of any watch work more than 12 hours in any 24-hour period, except in an emergency.CGD 81-059, 52 FR 38652, Oct. 16, 1987, as amended by USCG-1999-6224, 64 FR 63235, Nov. 19, 1999; USCG-1999-5040, May 15, 2002; USCG-2004-18884, 69 FR 58343, Sept. 30, 2004; USCG-2006-24371, 74 FR 11261, Mar. 16, 2009; USCG-2004-17914, 78 FR 78004, Dec. 24, 2013; USCG-2012-0208, 79 FR 48924, Aug. 18, 2014; USCG-2015-0758, 80 FR 65168, Oct. 26, 2015