Fuel consumption and exhaust emissions reduction by dynamic propeller pitch control

The aim of this paper is to focus attention on how a proper control strategy can save both: fuel consumption and exhaust emissions. A ship with a Controllable Pitch Propeller, driven by a diesel engine or a gas turbine, is traditionally controlled via the "combinator" that set a proper combination of pitch and shaft speed depending on the bridge telegraph (lever) position. The propulsion control based on a 'static' combinator curve does not assure the best use of the propulsion system in terms of power, consumption and emissions. The idea proposed here is to shift from the classic paradigm of 'static' combinator curve (or curves) to a 'dynamic set point' of the propulsion plant. A 'ship performance code' has been developed and used to evaluate the potential benefit of the adoption of the 'dynamic set point' control scheme with respect to the traditional 'combinator' control scheme. Some simulations have been performed and results compared with full scale data measured during normal ship service. The technological implementation seems straightforward, at the present state of the art, for what the automation (propulsion controllers) is concerned, instead, it will probably require some improvements for what the pitch control system is concerned. © 2009 Taylor & Francis Group, London.