Weathervaning instabilities of a FPSO in regular waves and consequence on response amplitude operators

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Conference26th International Conference on Offshore Mechanics and Arctic Engineering, 10-15 June 2007, San Diego, Califormia
AbstractA series of model tests in regular seas were performed on a 1:60 scaled model of a generic FPSO. The model was moored by means of four instrumented mooring lines attached to an internal turret. The wavelength to model length ratio was varied from 0.5 to 2.0, while the ratio of the wavelength and the wave amplitude was kept constant as per ITTC seakeeping recommendations. The goal of the tests was to evaluate the response of the hull to swell conditions that may happen in open sea environments and to assess the weathervaning characteristics of the internal turret arrangement. During the tests the six accelerations and six displacements have been measured by means of an inertial and optical system respectively, together with the wave elevation in the basin. From the results, motion response amplitude operators were obtained at different heading conditions. The experimental results for the model displacements were compared with simulations from the well-known diffraction program WAMIT/WADAM. The paper will discuss possible reasons for the yaw instabilities, including the effect of moorings and test duration. The influence of the heading changes on the RAO of the hull with and without constraints will be discussed. Finally, RAO comparison with SESAM will demonstrate similarities and differences with RAOs at different sea headings.
Publication date
AffiliationNRC Institute for Ocean Technology; National Research Council Canada
Peer reviewedYes
NRC number6513
NPARC number8895868
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Record identifierc8d04186-5c21-4e18-ac17-d86a3d90948a
Record created2009-04-22
Record modified2016-05-09
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