46 CFR § 169.563 - Firehose.
(a) One length of firehose must be provided for each fire hydrant required.
(b) Vessels less than 90 feet in length must have commercial firehose or equivalent of not over 1 1/2 inch diameter or garden hose of not less than 5/8 inch nominal inside diameter. If garden hose is used, it must be of a good commercial grade constructed of an inner rubber tube, plies of braided cotton reinforcement and an outer rubber cover, or of equivalent material, and must be fitted with a commercial garden hose nozzle of good grade bronze or equivalent metal.
(c) Vessels of 90 feet or more must have lined commercial firehose that conforms to UL 19 or Federal Specification ZZ–H–451(incorporated by reference, see § 169.115). The firehose must be fitted with a combination nozzle approved under § 162.027 of this chapter.
(d) Each length of firehose must be a single piece 50 feet long.
(e) Firehose must be connected to the hydrants at all times, except that, on open decks where no protection is afforded to the hose, it may be temporarily removed from the hydrant in heavy weather and stowed in an accessible nearby location.