The role of trenching tools in undersea cable laying

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Subsea cables are key to the growth of global communications networks, as well as communication between oil platforms and from fields to the shore end.

Installing and protecting these subsea cables is an absolute priority due to the financial investment involved and the need to reduce the risk of the purchasing company. As such, when cables are being laid a variety of tools and processes are used to ensure the cable is properly installed and protected.

After the survey, planning, permitting, manufacturing and testing processes have been completed, the laying process can begin. Several tools - with constant supervision by expert personnel - are used.


The injector is a deep burial installation tool, using hydrojet technology designed and patented by Global Marine Systems. By passing gas through the seabed soil, cables can be laid with minimal tension - key for the long-term life of cables.

This tool is generally used in softer soils to achieve 7-10 metre burial depth and can be used in waters up to 40 metre diver depth.

Rocksaw Trencher

The seabed isn't all soft soil, and sometimes what appears to be a soft surface can be a layer of soil covering the sedimentary rock below it. In this case, the plough and injector won't work for cable burial and a rocksaw trencher is required.

The rocksaw trencher is capable of burying subsea cables to depths of up to 4 metres. Driven by a 2000 HP hydraulic power pack, the rocksaw trencher is able to bury cables in a variety of environments, and in diver depths up to 40 metres.

Burial sleds

Another set of burial vehicles, burial sleds are able to bury cables with or without articulated steel pipe protection. Certain sleds, such as the Viper, are designed for deep cable burial and fitted with a wide range of instrumentation to ensure high quality installation.

The standard burial stinger provides 3.25m burial, and other configurations are available to suit a variety of requirements. Viper is designed for either surface water fed operations in shallow water or can be fitted with submersible pump/motor sets for diver-less operations down to 200m water depth.


In deep water, ploughs are capable of installing cables, repeaters and cable splice boxes at water depths of 1,500 metres. Ploughs are equipped with cable tracking systems and forward obstacle avoidance sonar. The Hi-Plough was introduced in 2001 and has a remarkable track record for achieving deep cable burial protection.

Global Marine Systems has a comprehensive background in engineering and subsea services. We specialise in providing fibre-based data networks for oil & gas and telecommunications cable systems, continually leading in design and engineering around the world.

For more information on subsea cable installation, maintenance and burial requirements, contact Global Marine Systems today at


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