Performance Values vs. Speed – A Declaration of Independence?

Paper in proceedings, 2018

Percentage speed loss due to a deteriorated condition of hull and propeller is used as performance value in ISO 19030:2016. However, for a number of reasons, this performance value is speed-dependent. In this paper, equivalent sand roughness height is proposed as an alternative performance value, being calculated from increased shaft power due to hull-and-propeller condition. Results for a Panamax tanker (noon reports) are analysed and discussed. It is argued that uncertainties for final performance indicators can, in principle, be similar or even lower than using percentage speed loss, while removing some of the speed dependency detected in the percentage speed loss.