Large underwater equipment used in deep-sea engineering, which needs mooring line in order to hang down while using pendulous installation method in 1500m deep-water installation. During the procession, the mooring line will suffer the vessel’s pull, large equipment’s traction, fluid force leading to elongation, bending and other deformation, so need to analyze its motion. Aiming at the numerical simulation problem of underwater equipment installed by pendulous installation method in deep-water environment, this paper combines lumped mass method, three-dimensional potential theory and Morison equation to establish the analysis model of the whole installation system. Under the different horizontal dropping offsets of the equipment, this paper computes not only tension of mooring line, but motion performance of underwater equipment and working vessel during the pendulous lowering phase.
The Pendulous Installation Method (PIM) puts a working vessel, a mooring line and a underwater equipment installed in succession, and there is a coupling interaction among them, so it is essential to do time-domain coupling analysis. So the Orcaflex Software is used to simulate the entire deep-water installation system. Using different horizontal dropping position as a variable, we can get the contrast about the different movement states of the mooring line and underwater equipment, and finally we will get the conclusion.