On a ship, the fire room, or FR or boiler room or stokehold, referred to the space of a vessel where water was brought to a boil. The steam was then transmitted to a separate engine room, located immediately aft, where it was utilized to power the vessel. To increase the safety and damage survivability of a vessel, the machinery necessary for operations may be segregated into various spaces, the fire room was one of these spaces, and was among the largest physical compartment of the machinery space. On some ships, the space comprised more than one fire room, such as forward and aft, or port or starboard fire rooms, or may be simply numbered. Each room was connected to a stack ventilating smoke.