Review of Cabling Techniques and Environmental Effects Applicable

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Review of Cabling Techniques and Environmental Effects Applicable to the Offshore Wind Farm Industry – Technical Report cutting through the seabed. The cable is then fed through the pathway in the plough and the wedge of soil placed as cover over the cable. The cable laying operation involves cable being laid from the host vessel (usually over the stern of the vessel) with a managed catenary down to the bellmouth entry in the cable plough. The simultaneous lay and burial of the cable is then achieved as the cable vessel makes forward progress and the cable plough buries the cable as described above. Depth of burial is controlled by varying the deployed position of the hydraulically controlled skids and the plough is fully instrumented with cameras and sensors to monitor the passage of the cable through the plough and to also measure pitch and roll, depth of burial, distance travelled by the plough and residual tension in the installed cable. Figure 3.11 shows a typical narrow share plough with the range of sensors and components illustrated. Figure 3.11: Typical Narrow Share Cable Plough Illustrating Sensors and Plough Components These types of plough can typically achieve a depth of burial of up to 1.0m in a wide range of seabed conditions and have been successfully used on telecom, power cable and UK offshore wind farm projects. A selection of commonly used narrow share cable ploughs including details of the manufacturers and owners is listed in Table 3.6. 38
Cable types and installation techniques Table 3.6: Selection of Commonly Used Narrow Share Cable Ploughs PLOUGH CONVENTIONAL NARROW SHARE CABLE PLOUGHS Type Maximum Burial Depth Operator Manufacturer Cable ploughs (several ploughs deployed worldwide) 1.0m to 1.5m Global Marine Systems SMD Hydrovision Ltd Sea Stallion Cable Plough 2.0m Bohlen & Doyen The Engineering Business Ltd Sea Stallion Cable Plough 2.0m Originally Cns Ltd The Engineering Business Ltd Sea Plows (several ploughs deployed worldwide) 1.5m Tyco Submarine Systems SMD Hydrovision Ltd Figure 3.12 shows a cable plough being deployed from a purpose built launch and recovery system installed on the deck of the host vessel. Figure 3.13 shows a conventional narrow share cable plough burying an offshore wind farm power cable away from the shoreline at North Hoyle. This figure clearly illustrates that only a minimum disturbance occurs on the beach or seabed during a cable burial operation using this type of plough. The plough share is deployed to a maximum depth of penetration of approximately 2.0m. The ‘disturbed’ mounds of sand adjacent to the cut trench are approximately 300mm to 400mm high. Figure 3.14 shows the same cable plough burying the North Hoyle Offshore Wind Farm export cable up the beach with the offshore wind farm in the distance. Figure 3.12: Cable Plough Launch and Recovery from a Host Vessel (Photo courtesy of The Engineering Business Ltd) 39
Page 1: REVIEW OF CABLING TECHNIQUES AND EN
Page 4 and 5: Review of Cabling Techniques and En
Page 9 and 10: Abbreviations AIS Automatic Identif
Page 11: TTS Temporary Threshold Shift TWA T
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Review of Cabling Techniques and En
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6 Good practice measures This secti
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7 Gaps in understanding Research fo
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References Introduction Sinden, G.
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Appendix A: Standards and codes of
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Printed in UK on recycled paper. De
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