The Boiler and Engine Rooms

HMS Belfast's main propulsive machinery is laid out according to a system first introduced by the United States Navy, known as Unit Propulsion. This system was based upon the grouping together of the boilers and engines into self-contained units. A single hit from an enemy shell or torpedo could therefore never disable more than 50% of the ship's power plant.

Forward Boiler Room

The entrance to the Forward Boiler Room is guarded by a double set of doors forming an airlock into the huge compartment beyond. This was essential as any sudden change in air pressure could result in the boilers 'flashing back' and incinerating anything, or anyone, in front of them.

HMS Belfast's boilers burned a heavy oil mixture, known as Furnace Fuel Oil, to produce superheated steam at a pressure of 350 pounds per square inch.

The steam was then piped through to the turbine engines, which in turn drove the propeller shafts. It took about four hours to raise sufficient steam to get the ship under way.

Forward Engine Room

HMS Belfast has four propeller shafts, the two outer ones driven by the engines in the Forward Engine Room and the inner ones driven by engines in the After Engine Room. Each of the four turbine engines is capable of generating 20,000 shaft horsepower, making a total of 80,000 shp (an average family car develops 100 hp), enough to drive HMS Belfast through the water at 32 knots - or 36 miles per hour (58 kph).

Each engine has four distinct turbine rotors: the two large high and low pressure turbines, which worked in series to develop full power ahead; a small cruising turbine for more economical speeds; and an astern turbine.

The superheated steam from the boilers could be directed to the desired combination of rotors by means of control throttles, driving the turbines, which in turn drove the propellor shafts through the gearbox mechanism attached to each engine.