Effect of Polyester Rope Damping on Behavior of Offshore Floating Units

Today the use of polyester ropes for mooring floating units in deepwaters is increasing around the world especially in Campos Basin, offshore Brazil. Several papers pointed out the advantages of polyester ropes in deepwaters. However the effect of damping of the material is not completely studied. The aim of this paper is to evaluate the effect of polyester rope damping on behavior of offshore floating units. The hysteresis cycles have been studied using dynamic tests of long duration. There are two types of tests: variable and constant mean tension tests. For evaluating the energy dissipated in each cycle software for calculating the hysteresis cycle area was developed. Using dimensional analysis it is proposed a model that defines the behavior of line damping and using this model and simulation of a FPSO unit the line damping is calculated.