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Last updated 23 Apr 2018 Original issue 4 Jul 2014

Wave Hub Subsea Cable Safety Notification

Mariners are reminded to exercise caution when navigating in the vicinity and are advised not to anchor or fish within the Wave Hub offshore site (as defined by the four special marks and charted as ‘Renewable Energy Development Area’) or in proximity to the main export cable.

Please be advised that the subsea cable system safety notification remains in force and the system is live at 11,000V. The majority of Wave Hub subsea cables are surface laid with varying levels of protection and alongside a dynamic seabed present a potential snag risk to anchors or fishing gear.

The following safety information and downloads should be carefully digested by any mariner operating in the vicinity of the Wave Hub offshore site or export cable route:

1. Overall, the 2017 cable survey shows that approximately 18% of the export cable remains exposed.  Key characteristics are as follows (KP chart and RPLs attached):

  • From the shore to KP1.9 the subsea power cable remains buried to the design depth of 1.5m from top of product
  • Due to varying sediment depths alongside shallow burial or a partial rock berm, From KP 1.9 to KP 8.1 the subsea power cable is in many areas exposed or carries a high risk of exposure
  • From KP 8.1 to the Wave Hub itself (KP 25) the subsea power cable is generally covered by a rock berm with 0.3m depth of cover. However, the 2017 survey has recorded a number of longstanding cable exposures and free-spans through this zone so the berm should not be considered as continuous protection.

 

2. Four cable tails extend across the charted offshore Renewable Energy Development Area to provide Developers with a proximate point of connection (KP chart and RPLs attached). These cables are stabilised against current and wave action through rock bags positioned at regular intervals but are otherwise exposed and unprotected to facilitate ease of handling. Many free-spans were removed in 2016 during construction by use of further rock bags but further free-spans due to the seabed mobility have been recorded during the 2017 cable survey.

Supporting Wave Hub References:

  • Export Cable KP Chart
  • Cable Tails KP Chart
  • Cable Route Position Lists (Asset Location Database)
  • Cable System Schematic

 

Further Notes:

  • The Wave Hub export cable is charted on UKHO Admiralty charts of the area as a ‘Submarine Power Cable’ with the warning that ‘Mariners are advised not to anchor or trawl in the vicinity of submarine cables’.
  • The offshore site is charted as ‘Renewable Energy Development Area’ with the warning that ‘Mariners should exercise caution when navigating in the vicinity’.
  • As of April 2015 the Wave Hub Development Area and cable route has been included in the Kingfisher KIS-ORCA awareness charts and plotter updates for fishermen.
  • The Wave Hub Notices to Mariners web page will hold the latest safety information for mariners operating nearby and should be checked regularly.

 

Downloads