Review of Cabling Techniques and Environmental Effects Applicable
Review of Cabling Techniques and Environmental Effects Applicable
Review of Cabling Techniques and Environmental Effects Applicable
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3.8.5 BURIAL SLEDS<br />
Cable types <strong>and</strong> installation techniques<br />
Most burial sleds are developed for the burial <strong>of</strong> the shore end section <strong>of</strong> cable<br />
systems <strong>and</strong> work in shallow water. As well as being used for open water shore<br />
end cable installation, these machines are <strong>of</strong>ten used for river crossing <strong>and</strong><br />
estuary cable work.<br />
Most <strong>of</strong> the systems are relatively simple in their technology <strong>and</strong> consist <strong>of</strong> a<br />
basic frame structure to provide a pathway for the cable <strong>and</strong> a simple hydraulic<br />
function to allow for a jetting tool to be deployed to the required depth <strong>of</strong> cable<br />
burial. In most instances the water pumps for the jetting tools are provided from<br />
the host vessel with pipework direct to the burial sled. These low cost shallow<br />
water burial tools inevitably require diver intervention for cable loading <strong>and</strong><br />
unloading.<br />
Burial sleds are also used in shallow water areas where the seabed or intertidal<br />
zone consists <strong>of</strong> very s<strong>of</strong>t muds or where seabeds will not provide any bearing<br />
support to a tracked cable burial vehicle or a conventional subsea plough.<br />
The burial sled is likely to be a lot lighter than these types <strong>of</strong> burial machines,<br />
particularly if the burial systems utilise surface powered jetting systems which<br />
negates heavy subsea pumps <strong>and</strong> motors. It can be possible to make these<br />
burial sleds almost neutrally buoyant by the attachment <strong>of</strong> temporary buoyancy<br />
<strong>and</strong> diver lift bags. Hence, the lightweight configuration allows the burial<br />
sleds to work in s<strong>of</strong>t seabeds which would be out <strong>of</strong> the range <strong>of</strong> other burial<br />
machines.<br />
A selection <strong>of</strong> typical burial sleds which are currently used worldwide are<br />
listed in Table 3.13. The same table also includes details <strong>of</strong> injector systems.<br />
Injectors are large specialised jetting tools which are typically used in harbours<br />
<strong>and</strong> anchoring areas where deep burial is required (up to 10m). These units are<br />
powered from the surface <strong>and</strong> use massive pumps <strong>and</strong> power packs to deliver a<br />
very potent force into the seabed to achieve the depth <strong>of</strong> burial required.<br />
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