Experimental and Numerical Evaluation of Manoeuvring Capability of an AHTS Using Free-Running Tests

Abstract

Investigating the hydrodynamics of a ship manoeuvring is a continuing concern for researchers. In recent years, with the growth of the operations complexity, understanding the hydrodynamics of a ship manoeuvring has become a central issue for supply vessels operating in close proximity of oil platforms. One of the main obstacles in understanding this problem is the difficulty of reproducing the manoeuvring on real ships with acceptable measurements, uncertainties and environmental control, not to mention the cost involved. A natural approach to address the issue is to run model tests, where it is possible to control a great number of variables. In the desire to develop new methods to evaluate hydrodynamic coefficients and to improve the understanding of the phenomena, this paper proposes different types of free-running tests to be conducted in an experimental ocean basin. An Anchor Handling Tug Supply Vessel (AHTS) scaled model was used to perform the classic turning circle and the novel turning eight, a substitute to the zigzag that fits in limited manoeuvring facilities. Optimizations of mathematical manoeuvring models were applied to estimate the hydrodynamic coefficients with a new proposed metric of manoeuvres comparison. Simulations results were compared with the experimental measurements of the model during the tests. The experimental tests were performed at LabOceano, the Ocean Technology Laboratory of the Federal University of Rio de Janeiro.