Review of Cabling Techniques and Environmental Effects Applicable

Cable types and installation techniques
Another type of Advanced Cable Plough is the modular cable plough, the concept
for which was originally conceived in the 1980s. The principle of the modular
plough is to have a plough system with an interchangeable plough share which
allows the operator to either fit a narrow share for cable burial or to fit a modular
V-type share for the burial of flowlines or small flexible pipelines.
This type of plough has not proved popular and most operators have opted to
design and build a plough system specifically tailored to the market they wish
their plough system to operate in. An example of a modular plough is detailed
in Table 3.8 below. It is believed that this plough system has only been used in
cable burial mode; however, this has not been confirmed.
Table 3.8: Modular Cable Ploughs
PLOUGH MODULAR CABLE PLOUGHS
Type Maximum Burial Depth Operator Manufacturer
Modular plough system
(cables or pipes)
Rock ripping ploughs
1.2m CTC Marine Projects SMD Hydrovision
Ltd
The Rock Ripping Ploughs were developed in response to requirements from
the subsea telecommunications market to provide a capability to protect
cables in areas where telecom cables passed over seabeds which consisted of
outcropping rock, or where the seabed strata was exceptionally hard and outwith
the capabilities of a conventional narrow share plough. This requirement was
primarily driven by fishermen trawling in seabed areas where such seabed
conditions exist. Historically the fishermen would have avoided such areas
owing to the risk of snagging gear. However, the need to find new fishing
grounds has now forced the fishermen to work in these more difficult areas and
in deeper waters.
Historically when a cable had to be buried in rock the traditional approach would
have been to use a rock wheel cutter. These tools can cut an efficient trench,
but tend to make relatively slow progress depending on the nature of the rock.
Furthermore, the wear rate on the cutting teeth can be substantial. Therefore, the
rock ripping plough was developed to meet this new challenge.
A Rock Ripping Plough has an additional, folding, rock penetrating tooth which
is fitted to the leading edge of the plough share. The rock penetrating tooth
significantly increases the ability of the rock ripping plough to penetrate and cut
trenches in very hard ground seabed conditions. The overall performance of the
plough is not generally affected in any way when the plough is cutting the trench
in rock ripping mode.
Table 3.9 lists a number of rock ripping ploughs which are currently available in
the marketplace. Figure 3.17 shows a rock ripping plough; the rock penetrating
tooth is clearly visible on the leading edge of the plough.
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