The offshore telecommunications industry

The industry
Subsea telecommunications to date consist of a network of over 450,000 kilometres of cable spread all around the world. Submarine cable systems have largely replaced satellites and carry the bulk of communications for both voice and data across the oceans; one fibre (a cable includes several fibres) can carry as much as one satellite system. For example, trans-Atlantic cable carries 90 per cent of international communications, although satellite systems will always be used for mobile services and access to more remote and rural areas.

Subsea cables are owned and operated by numerous companies such as FLAG (fibre optic link around the globe) Global Crossings, Southern Cross and others. They are put into place by subsea cable installation and maintenance contractors such as Tycom, Alcatel, Global Marine Systems or CTC marine projects, who carry out the laying, burial, maintenance and even the initially planning and management of the cable laying, to the specifications required by the client companies.

The subsea telecommunications industry has recently suffered similar reversals to other telecoms sectors, showing a reduction in size, structure and competition. However, business forecasts predict that there will be an upturn towards the end of 2003/2004.

Cable burial
The burial of a cable like a trans-Atlantic one will be performed by specialist cable ships capable of carrying several hundred kilometres of subsea cable in specialist cable tanks, with the cable normally starting at a terminal located on the beach. The beach end of the cable could be buried using a seabed tractor, which in some cases can be driven from the beach. Once into deeper water several options would be available, and the one selected would depend on a number of different factors, including the hardness of the sea bed, the depth of the water and the risk to the cable from such hazards as fishing trawl gear. This last hazard has increased significantly over the past ten years as fishing techniques have become far more aggressive. Anchors and seabed activity such as shifting sand banks and seismic activity can all add to the problems faced.

The client or cable owner/operator usually specifies if the cable is to be buried, with most cable laid in water deeper than 1,500 metres being 'surface laid'. (As water depths become greater, the risk of inadvertent damage to the cable from such hazards like those mentioned above decreases significantly. Cables located at depths of less than 1,500 metres are usually buried using one or more of a variety of vehicles.

The most cost-effective and quickest method of cable burial is through the use of a subsea cable plough working in 'simultaneous lay and burial mode'. As the cable to be buried leaves the ship, the plough - towed behind the ship - digs the trench, immediately lays the cable and then fills in the trench. This has the advantages of protecting the cable from potential damage almost immediately it has left the ship, and achieving a good quality of burial because the seabed replaced over the cable can resist penetration by trawl gear, anchors and other hazards. Subsea cable ploughs are able to bury cable at speeds in excess of 2 knots - the equivalent of 120 kilometres of cable a day.

The alternative is 'post-lay burial.' This procedure involves the cable first being surface laid on the seabed by one ship, with a second ship following using either a seabed tractor or cable ROV to bury the cable using either high- and low-pressure water jets and/or mechanical cutting wheel and chains.

Job roles
There are a number of job roles in the subsea telecommunications industry. They include:
• ROV personnel, ranging from trainee ROV pilots and technicians through to supervisor grades
• offshore and onshore project managers
• route engineers
• permit engineers
• offshore installation managers and superintendents
• surveyors
• cable engineers
• cable jointers
• multi-skilled systems engineers.