Retrieval and deployment of marine tethers

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Conference18th International Conference on Offshore Mechanics and Arctic Engineering, 11-16 July 1999, St. John's, Newfoundland
Subjectmarine tethers
AbstractA submerged subsea unit attached at one end of a tether is controlled in retrieval and deployment modes by the torque applied to a fixed drum around which the tether is wrapped. The dynamics of the system is studied and the equations of motion of the deployed portion of the tether is considered together with the drum rotation. Stretch in both deployed and undeployed parts of the tether are examined and simulated. Included in the analysis are the hydrodynamic effects due to the motion of the subsea unit and the deployed portion of the tether attached to it in a marine environment assumed otherwise at rest. The motions of the drum, tether and attached mass are analysed with respect to the longitudinal vibrations of the tether. A feedback controlled torque is expressed as a function of the state variables, target length and velocity of deployed tether. A strategy for the deployment and retrieval of unit to a prespecified depth is suggested and simulation results for a specific example presented. Estimations of the state variables and their rate of change together with the tether tension and applied torque on the drum are provided. The present study and results are a basis for a full analysis of the pay-in and pay-out problems in marine tether dynamics.
Publication date
AffiliationNRC Institute for Ocean Technology; National Research Council Canada
Peer reviewedNo
NRC number5788
NPARC number8895650
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Record identifier23f41bb6-1d51-410f-9894-26de78561155
Record created2009-04-22
Record modified2016-05-09
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