There are two ways to reduce the speed of a ship. One could throttle down by reducing the number of nozzles feeding high-compression steam from the boilers into the turbines. Or, one could reduce the steam pressure in the boilers. The latter was the practice on the Andrea Doria. It was cheaper to reduce steam pressure and burn less fuel although cutting steam pressure reduced the power and maneuverability of the ship in event of emergency, for it takes far longer to build up boiler pressure than to open closed turbine nozzles.
Never heard this method mentioned before! Wonder how much fuel it actually saves,
