On the Prediction of Wave-added Resistance with Empirical Methods
Author Grin, R.
Title On the Prediction of Wave-added Resistance with Empirical Methods
Conference/Journal Journal of Ship Production and Design
Paper no. DOI: 10.5957/JSPD.30.4.130060
Month November
Year 2014
Volume 30
Number 4
Pages 11

THE PREDICTION of wave-added resistance is important for several reasons. In heavy weather safety aspects are most important.
Is the ship able to sustain sufficient speed to maintain heading and is the main engine able to cope with the overload? In moderate weather conditions, fuel economy is most important. In these conditions, the power demand increases when speed is sustained or when sailing at constant power the added resistance will result in speed loss.

The safety and economic aspects can already be studied in the design stage with so-called operability studies. These studies account for the actual service conditions and assist the designer
to optimize for service conditions and to select an appropriate service margin. When the service margin is too low, safety might be at risk and the reliability in terms of arrival times will be low.
When the service margin is too high, the main engine will run most of the time at inefficient power settings and (future) energy efficiency design index (EEDI) requirements might not be met.
Within the present work we compared two recently developed empirical prediction methods, two established empirical methods developed in the 1970s and experimental data in regular waves
and irregular seas. The first new method (STAWAVE2) predicts added resistance in head seas only and has been developed within the Sea Trial Performance Joint Industry Project (STA-JIP). The goal of this JIP was to improve transparency and accuracy of speed trials. One of the requirements was to deliver a reliable correction method for wave-added resistance. The second new method (SPAWAVE) is suitable for all wave directions and has been developed within the service performance analysis joint industry project (SPA-JIP). This JIP aimed at the reduction of fuel consumption by careful analysis of the vessel performance in service conditions.

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