Analysis of uncertainties in the prediction of ships’ fuel consumption – from early design to operation conditions

Abstract

This investigation presents an approach towards a better understanding of achievable accuracy of fuel consumption predictions of ships and provides an example of how a thorough uncertainty analysis of prediction models can be performed. A generic ship energy systems model is used for the fuel consumption prediction of two reference ships: a RoRo ship and a tanker. The study presents how uncertainties can be categorised and handled in four different phases of a ship's life -from early design to ship operation. Monte Carlo simulations are carried out for two environmental conditions to calculate the mean and uncertainty of the fuel consumption. The results show that the uncertainty in the fuel consumption prediction in a very early phase of the design process is approximately 12%, whereas at a very late phase, it reduces to less than 4%. Finally, the simulation model is applied to a real ship during operation conditions.

A 4 DOF simulation model developed for fuel consumption prediction of ships at sea

“…A generic energy systems model has been developed and is presented in Tillig et al (2017Tillig et al ( , 2018. It can be used to simulate and analyse the power and fuel consumption predictions for arbitrary merchant vessels under realistic operational conditions with very limited required input.…”

“…The model consists of two parts, a static power prediction called ShipPOWER and a dynamic operation simulation model called ShipJOUR-NEY. ShipPOWER is the static part of the model which is described in Tillig et al (2017), where different levels of prediction uncertainties are discussed and presented in detail in Tillig et al (2018). The required minimum inputs are the principal dimensions (length, beam, draft, displacement), the design speed, the propeller arrangement and the propeller and engine rpm.…”

“…bulbous bow dimensions and superstructure areas), (ii) the linear hydrodynamic derivatives for the dynamic force and moment balance; see Section 2, (iii) a resistance and power prediction at calm water without wind, (iv) a power prediction with Seas state four head waves and Beaufort four head wind, (v) a propeller design from the standard series, and (vi) the engine limits. Compared to the model used in Tillig et al (2018) the estimation of the hydrodynamic derivatives is added based on different empirical formulas, as described in detail in Section 2. In addition, the dynamic route simulation part of the simulation model presented in Tillig et al (2017) has in the new simulation model been completely reprogrammed in Matlab, and extended to capture 4 DOF by solving the force and moment equations for the surge, drift, yaw and heel.…”

“…The present study presents a new simulation model for the prediction of the fuel consumption of commercial ships at sea, solving the force and moment balance for 4 DOF. The model is based on former work and a 1 DOF simulation model presented in Tillig et al (2018). It accounts for engine limits, differences in propeller efficiency and engine fuel consumption due to possible off-design operation.…”

Experimental Research on the Energy Efficiency of a Parallel Hybrid Drive for an Inland Ship

“…At the design stage of a ship, the main propulsion power is usually chosen for the contracted speed, which in practice is often close to the maximum speed of the ship. The fuel consumption can be predicted with uncertainty equal 12% up to 4% depending on the design stage of a ship [19].…”