OFFSHORE DRILLING OR PRODUCTION VESSEL

The invention relates to an offshore drilling or production vessel comprising a platform and a mooring system attached thereto , said mooring system comprising: i.) a support frame with a winch- drum mounted thereon; ii.) a mooring line for mooring said platform to the ocean floor , said mooring line comprising a first portion and a second portion; wherein said first portion is hauled on and paid off by said winch- drum; wherein said second portion is anchored to the ocean floor; characterized in that the mooring line is a single length mooring line comprising high strength polyolefin fibers; wherein the first portion of the mooring line has a first mass (M1) of polyolefin fibers per unit length and the second portion of the mooring line has a second mass (M2) of polyolefin fibers per unit length; wherein the ratio M1/M2 is greater than 1 and wherein said first portion extends continuously into said second portion through a tapered portion of the mooring line.