Review and historical overview of experimental facilities used in hull coating hydrodynamic tests

The prediction of hydrodynamic performance of hull coatings with different surface conditions is a challenging task. Moreover, with the emergence of new prototype coatings that are relatively smooth in terms of roughness characteristics, the accurate estimation of their drag is particularly important, as this will enable a good grading of drag reducing benefits of coatings. In the context of coating studies, the experimental methods are considered as the backbone and results obtained from experimental facilities with the required performance will enable accurate scaling of test results to full-scale ship results. Although numerical simulations like computational fluid dynamics have acquired the level of accuracy good enough to replace some of the systematic model testing used for ship design optimization, it is still not evident whether the simulations will be able to replicate the physical reality such as coating type, its roughness and biofilms accurate enough to enable predictions of the power requirements for ships. Therefore, this article gives insight into various coating hydrodynamic testing facilities and methods that are capable of measuring drag characteristics of coatings. The work highlights the details of each method and identifies the concepts and parameters needed to describe, implement and analyze hydrodynamic coating drag measurements. This article also summarizes the merits and demerits of each type of facility based on reports and studies reported in open literature. Finally, the authors propose a recommendation that can be incorporated into the design of the new hydrodynamic facility.