46 CFR §118.310

1. (a)Except as required by paragraph (d) of this section, a vessel must have a sufficient number of fire hydrants to reach any part of the vessel using a single length of firehose.
2. (b)Piping, valves, and fittings in a fire main system must comply with part 119, subpart G of this subchapter.
3. (c)Each fire hydrant must have a valve installed to allow the firehose to be removed while the fire main is under pressure.
4. (d)On a vessel carrying more than 600 passengers or with overnight accommodations for more than 49 passengers, the fire main and hydrants must meet § 76.10-10 of this chapter.
5. (e)Spanner wrenches must be provided for each fire hydrant required by this regulation. Existing vessels must comply with this requirement by January 18, 2017.