Selection of provisional route
Once the requirement for a cable
system has been identified and funds raised to build it, the first
thing which happens is that a cable manufacturer and installer is
contracted by the cable system parties.
A desk top study is then
commissioned which identifies a route and the risks to that
Items for consideration would be
Landing Points, Territorial
waters, Contiguous Zones (CZ) and Exclusive Economic Zones (EEZ)
i.e. the Maritime Boundaries;
Branching Unit deployments;
Geopolitics - Contested
Whether the cable landings can be
made directly or have to be pre-laid;
Permitting & Fisherman
Natural and manmade
obstacles/hazards such as weather conditions prevailing, currents,
seabed conditions, Mineral and/or Oil & Gas exploration,
Pipelines, other submarine cables, areas of environmental concern,
conservation area etc.
Obtaining permission from the relevant authorities
When the route has been selected
and designed, then the initiation of acquisition of permits for the
cable system is undertaken. This will involve engagement with
Government Administrations, other seabed users and stakeholders
i.e. fisheries, cable owners, pipeline owners, etc.
Full survey of route and its final selection
The purpose of the route survey is
to identify a safe route for the cable. Even though the Desk Top
Study has identified the potential route, the Route Survey will
confirm the assumptions made. The Route Survey comprises:
- Collection of Bathymetry, geotechnical, sub-bottom and side
scan data to support route engineering, cable selection,
installation and burial.
- The data is made available for review real-time and thus a
final selection of the route can be made. Final route selection
will consider identifying the safest and most economical route,
will optimize cable selection and route length. Avoidance of any
hazards identified during the survey process can be made and cable
types to be used will be confirmed. An assessment of seabed
conditions is also made at this point for the buried sections of
Cable laying Operations
Once the route survey is complete
and the cable system design is finalised, manufacture of the cable
is undertaken. When manufacture of the cable is complete, it is
loaded to the cableship for deployment.
At the shore approaches where the
cable is landed (the shore end), burial is carried out by divers in
the shallow water. If the water is too shallow for the main lay
vessel to approach safely, a smaller shallow drafted vessel may be
lay used to lay the shore end.
|Cable Laying Operations
The main lay vessel (the cableship)
is used to lay the rest of the cable system. In water depths where
there are risks due to fishing and other man made activities such
as anchoring etc., the cable is generally buried to a target
depth of approximately 1 metre.
The cable is laid to conform to the
contours of the seabed to avoid cable lying in suspension. During
the cable laying process, the cable is being constantly tested to
ensure that no damage has occurred to it.
At the end of the cable lay, a
final splice is made to join the cable ends together to make a
connection between the cable stations. Final tests are then made to
ensure the cable is working correctly.
Notification of cable position to other marine users
Following the cable laying
operations, the cable positions will be notified to various
administrations such as Hydrographic Offices, the Regulatory
Administrations and other seabed users such as fisheries.