I have a question regarding the “unstretched mooring line length” listed in NREL/TP-500-47535 (Jonkman). What I’m understanding is that the undisplaced position of the tower is in the “stretched” configuration such that the length of an individual mooring line will be longer than the 902.2 m listed in the paper. Is that correct? I’m simply verifying.
The unstretched mooring line length is defined as the natural length of the mooring line in the absense of any tension. Tension will stretch the line, based on the value of the extensional stiffness. Because the tension is never really zero when a mooring line is used in a floating system, the length of the line from the fairlead to the anchor will always be longer than the unstretched length.
I hope that helps.