... Abstract The paper identifies the wave drift forces and low frequency damping induced by a wide range of extreme sea conditions on two floating units based on model test data, assesses the limitations of today's numerical procedures and proposes solutions to overcome the limitations. Since wave...

... a variety of earlier case studies including model tests are reviewed. It is found that several items may be critical in the proper prediction of LF wave forces in high seas and combined current and should be investigated further, in particular: – Wave-current interaction – Viscous wave drift forces...

... is the inherently weakly damped nature of a moored LNG carrier. Consequences in terms of system design, mooring analysis methodology and model test program will be discussed. Another issue specific to near- shore import terminals is the shallow water effects on the wave drift forces. These effects will be discussed...

.... Results of this approach include positioning accuracy and thruster loading in interaction effect control coefficient wave drift force semi submersible thrust force positioning accuracy azimuth angle coefficient environmental load subsea system otc 10955 model test upstream oil...

... tanker motions with a high reliability could be carried out. Based on this program it became also possible to compute accurately the matrices of the quadratic transfer functions of the second order wave drift forces in 1980, see Ref. 2. In order to compute the low frequency (1.f.) tanker motions...

... performs small amplitude WF pitch, heave and surge motions and relatively large amplitude low frequency surge motions around a mean surge displacement. The mean surge displacement is caused by the mean wave drift force and the steady wind force. The low frequency surge motions are due to the low frequency...

... ABSTRACT The mean and low-frequency horizontal wave drift forces on 2 types of semi-submersible structures in regular and in irregular waves are determined from model tests and calculations. For the measurement of the low-frequency drift forces in irregular waves use is made of a special...

... frequency amplitude reaction force high frequency motion equation wave drift force proceedings model test simulation chain-turret-moored tanker upstream oil & gas tanker frequency motion technology conference procedure wave frequency surge motion mooring system moored...

... surge decay test contribution irregular wave hull vessel motion equation offshoretechnologyconference mooring system upstream oil & gas friction surge low-frequency vessel motion wave drift low-frequency surge motion subsea system prediction wave drift force OTe 6660...

... spectra turbulence drift force wind speed model test wind spectrum wind velocity computation wave drift force tanker surge motion wind spectra frequencymotion wind force wave spectrum resultsof tot spectral density frequency spectrum upstream oil & gas OTC 6605...

... to severe weather areas. The behaviour of the moored system in wind, waves and current can affect design and operation aspects. References and illustrations at end of paper. 183 OTC 6219 (4) vessel with respect manoeuvring applications of turn and relatively following applies for a wave drift force vector...

..., which involves simple calculation, in contrast with more complex calculation procedures. INTRODUCTION The problem of predicting the low frequency motions of moored vessels has primarily concentrated on the calculation of the second order wave drift forces that provide the excitation for such motions...

... ABSTRACT In this paper the basic expressions for the computation of mean and low frequency second order wave drift forces on floating structures in directionally spread seas as can be derived from potential theory are discussed. The resultant expressions for the mean and slowly varying drift...

... low frequency transfer function model test forward speed computation natural frequency coefficient regular wave tanker surge motion wave drift force surge direction frequency quadratic transfer function wave-current interaction effect moored tanker equation OTe 5631 Wave...

... interpretation. This paper is partly a review of recent theoretical and experimental work on low-frequency wave drift forces, damping and response, and partly a description of work now in progress at British Maritime Technology. Numerical calculations, using the NMIWAVE wave diffraction computer program...

.... The material is subject to correction by the author. Permission to copy is restricted to an abstract of not more than 300 words. . ABSTRACT The motions and mooring loads of storage/pro- duction tankers are dominated by large amplitude. low frequency components related to wave drift forces. In the design stage...

... relative motion measurement wave condition relative motion standard deviation subsea system drift force wave direction feed-forward upstream oil & gas wind force force level wave drift force wave direction positioning drift force level simulation ship dynamic positioning...

... computer simulation oscillation simulation contribution coefficient wave drift force upstream oil & gas dynamic contribution drift force subsea system tanker equation low frequency moored vessel frequency total wave drift force formulation irregular wave resistance...

... proximi ty to the structure, and must be repeated at points along the drift trajectory. Drift is calculated by a time-stepping procedure, applied to the appropriate equations of motion. These require the zero-frequency added masses and wave drift forces, obtained by the diffraction calculations. Thus...

... the horizontal motions and, conse- quently, also the mooring forces. In order to pre- dict the amplitudes of the low _frequency resonant motions the magnitude of the second order wave drift forces and the values of the low frequency hydrody- namic damping must be known. The low frequency hydrodynamic potential...