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R.H. Charlier and Chr. P. De Meyer
Idle time for sea and weather conditions, traffic, maintenance and repair and
soon has to be calculated to estimate the net weekly production.
3.1.7.2.2 Cutter suction dredger
The relative density of the sand determines the maximum cutting production
depending on the cutter power available. This production has to be compared
with the suction capacity of the suction pump depending on the characteristics of
the pump, diameter of the suction pipe and the dredging depth.
The lower of the two productions will be considered when checking the
possibility to pump the sand with a given grain size over the required distance. If
the sand cannot be pumped over the required distance, a booster has to be
installed in the pipeline or a lower production accepted. Here too, idle time enters
into estimation of the net production.
3.1.7. 2.3 Stationary suction dredger
Special attention has to be paid to the depth of the groove which can be dredged.
If the sediment is not flowing to the entrance of the suction pipe, a stationary
suction dredge should not be used.
When loading barges, the same principles as for the trailing suction hopper
dredger apply. When pumping through a pipeline those of a cutter suction
dredger should be used.
3.1.7.2.4 Backhoe dredger
The production is mainly determined by the capacity of the bucket used, which is,
as mentioned before, depending of the dredging depth. The latter shall thus
mainly determine the production.
Even the cycle time to load and empty a bucket is mainly influenced by the
dredging depth and not by the sand characteristics, contrary to the suction
dredgers. Knowing the cycle-time (approximately 1 min.) and the bucket
capacity, the theoretical output is determined. The main factors influencing the
maximum potential output are the delays to advance the dredger and to change
the barges. Enough barges are needed to avoid waiting time for the dredger.
R.H. Charlier and Chr. P. De Meyer
Idle time for sea and weather conditions, traffic, maintenance and repair and
soon has to be calculated to estimate the net weekly production.
3.1.7.2.2 Cutter suction dredger
The relative density of the sand determines the maximum cutting production
depending on the cutter power available. This production has to be compared
with the suction capacity of the suction pump depending on the characteristics of
the pump, diameter of the suction pipe and the dredging depth.
The lower of the two productions will be considered when checking the
possibility to pump the sand with a given grain size over the required distance. If
the sand cannot be pumped over the required distance, a booster has to be
installed in the pipeline or a lower production accepted. Here too, idle time enters
into estimation of the net production.
3.1.7. 2.3 Stationary suction dredger
Special attention has to be paid to the depth of the groove which can be dredged.
If the sediment is not flowing to the entrance of the suction pipe, a stationary
suction dredge should not be used.
When loading barges, the same principles as for the trailing suction hopper
dredger apply. When pumping through a pipeline those of a cutter suction
dredger should be used.
3.1.7.2.4 Backhoe dredger
The production is mainly determined by the capacity of the bucket used, which is,
as mentioned before, depending of the dredging depth. The latter shall thus
mainly determine the production.
Even the cycle time to load and empty a bucket is mainly influenced by the
dredging depth and not by the sand characteristics, contrary to the suction
dredgers. Knowing the cycle-time (approximately 1 min.) and the bucket
capacity, the theoretical output is determined. The main factors influencing the
maximum potential output are the delays to advance the dredger and to change
the barges. Enough barges are needed to avoid waiting time for the dredger.