A parametric experimental study of low-frequency motions of single point mooring systems in waves

Abstract

This paper contains results of an extensive model test programme on the behaviour of singlepoint mooring (SPM) systems to investigate the influence on system response, as measured by motions and mooring forces, of variations of certain wave environment and system parameters. The variations of the environment were frequency and height of regular waves; tests were also made using irregular waves and were compared with the regular wave results. Neither current nor wind were included. The influence of the hawser was examined by varying its length and elastic properties. Tests were made to examine the influence of tanker draft and also to compare the measurements for the tanker with those for an elliptical model representation. Most of the experiments were carried out using a fixed mooring point because tests using an articulated column showed that the stiffness of the buoy or column had almost no effect on the low frequency motions. Finally, tests were carried out in a larger wave basin, at the Hydraulics Research Station, Wallingford, UK which provided broad confirmation of the measurements made in the smaller Heriot-Watt basin. The paper presents the main results and overall conclusions which can be drawn from the experimental work.