Subsea Trenchers

General

These machines are remotely controlled self-propelled crawler trenchers, fully hydrostatic or electro-hydrostatic driven from a power pack situated on board a support vessel or landing craft.

Trencher

The trencher can form a trench of various dimensions in the sea bed.  This is achieved by using an endless cutting chain which, if fitted with removable cutting tools of various sizes and shapes, can cope with alternative strata of material.  Behind the cutting chain various chutes can be mounted to install cables, flow lines, umbilical etc directly into the bottom of the trench.

Alternative techniques can be achieved such as:-

installing pre-laid cables, etc, from the sea bed into the trench or installing simultaneously by supply from the vessel into the trench.  Cable ducts and chutes can be hydraulically raised and opened to eject or insert cable for machine recovery.

Umbilical:

This unit is constructed from a number of hoses woven together and integrated with tension members.  Handling attachments are mounted at regular intervals to assist in its deployment, and the adding of buoyancy floats.

This consists of a complete self contained diesel power pack inclusive of fuel and oil supply preferably mounted in a conventional container giving maximum flexibility in adapting to different types of vessels and conditions.  The umbilical can be stored in the second half of the container and manipulated by a traction haul system during deployment and recovery operations.

All operating and monitoring functions for the complete installation are mounted in one unit.  This can be handled easily and positioned directly onto the power pack to give maximum flexibility for use on different vessels.

Support equipment:

To assist in some trenching environments, additional water and air may be required.  This would be provided by using a supplementary generator and compressor.