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    Heerema Marine Contractors installs first truss spar to use polyester mooring system

    Projects and Operations // February 4, 2005
    Heerema Marine Contractors (HMC) has successfully installed the first truss spar ever to use a polyester mooring system.

    The Mad Dog spar which is located in Green Canyon Block 782 in a water depth of approximately 1,348m is the first permanent polyester mooring system to be installed in the Gulf of Mexico.

    It has the largest diameter polyester rope ever made, with a jacketed diameter of 270mm and required the largest quantity of polyester mooring tethers ever produced for a single offshore mooring project.

    Using its Deepwater Construction Vessel (DCV) Balder, HMC installed several chain/spiral strand wire mooring systems. However, this was the first installation of a polyester mooring system. The Balder's unique large mooring line deployment winch was usedto handle the extensive quantity of polyester rope required for this project.

    In preparing the installation, the HMC project team took both the similarities and differences of installing a polyester system to a sheathed spiral strand system into consideration. Since polyester ropes may not come in contact with the seafloor, HMC developed procedures to keep the polyester off the seafloor during all phases of the installation.

    Another area where differences applied in the approach is the vulnerability of polyester rope for contact with sharp edges, steel wires and heat. Snagging or tearing of any of the fibres could reduce the efficiency of the ropes strength in the future.

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