Each accommodation space on a vessel must be ventilated in a manner suitable for the purpose of the space.
Means must be provided for stopping each fan in a ventilation system serving machinery spaces and for closing, in case of fire, each doorway, ventilator, and annular space around funnels and other openings into such spaces.
A vessel of more than 65 feet (19.8 meters) in length with overnight accommodations must have a mechanical ventilation system unless a natural system, such as opening windows, portholes, or doors, will provide adequate ventilation in ordinary weather.
source: USCG-2006-24412, 81 FR 40101, June 20, 2016, unless otherwise noted.
cite as: 46 CFR 144.605