IV. Retreating Shorelines
249
When in operation, the cutter suction dredger makes use of two stern spuds
arranged so as to allow the dredger to advance in steps towards the dredging face.
In each dredging position, the dredger is swung from side to side by means of
side wires anchored either side of the dredging area, the machine being pivoted
around one of the stern spuds. The suction tube may be raised or lowered by
means of a hoist wire.
The cutter suction dredger provides an almost continuous operation, the dredging
pump being stopped only when it becomes necessary to move the pipeline, either
due to the advance of the dredger or in order to discharge at a new location.
The basic subcycle is then : cut ; advance on spuds ; cut ; advance on spuds ;
(repeat as necessary) ; move side wire anchors. The main cycle consists of
repeating the subcycle as many times as necessary and then changing pipeline
position. Although the pumping process is continuous, at times the dredger
pumps only water, for example, when advancing or moving side wire anchors.
A cutter suction dredger can advance on its spuds, depending on the spud
arrangements in various ways. Spud systems work on the principle that one spud
is moved while the other is kept firmly in the seabed. Spuds are mounted at the
rear of the dredger and forward movement is achieved by swinging on one spud
until the other is ahead, then dropping it and lifting the first spud. In recently
built large rock cutter suction dredgers, the working spud is mounted in a mobile
carriage which allows the dredger to advance over a length of approximately 6 m
(+ 20 ft) without changing the spud. When the carriage reaches the end of its
stroke, the auxiliary spud is dropped, the working spud lifted and the carriage is
moved to its advanced position. Hence a new cycle can start after dropping the
working spud and lifting the auxiliary spud.
The cutter suction dredger requires side wires used for movements and control of
the dredged head. In hard material a considerable force is taken in the side wires
and the largest rock cutter suction dredgers have a side pull of about 300 [metric]
tons. Anchors must be, when the side wires are at an angle of 30 to 40 degrees to
the perpendicular, moved forward to a new position.
The cutter suction dredger is connected to the shore by its floating pipeline and so
as to allow the dredger to advance forward as far as possible without having to
stop dredging to avoid breaking the pipeline and either extend or move it.
Cutter suction dredgers are rated by the diameter of their discharge pipes and the
power on the sandpumps and on the cutterhead.
249
When in operation, the cutter suction dredger makes use of two stern spuds
arranged so as to allow the dredger to advance in steps towards the dredging face.
In each dredging position, the dredger is swung from side to side by means of
side wires anchored either side of the dredging area, the machine being pivoted
around one of the stern spuds. The suction tube may be raised or lowered by
means of a hoist wire.
The cutter suction dredger provides an almost continuous operation, the dredging
pump being stopped only when it becomes necessary to move the pipeline, either
due to the advance of the dredger or in order to discharge at a new location.
The basic subcycle is then : cut ; advance on spuds ; cut ; advance on spuds ;
(repeat as necessary) ; move side wire anchors. The main cycle consists of
repeating the subcycle as many times as necessary and then changing pipeline
position. Although the pumping process is continuous, at times the dredger
pumps only water, for example, when advancing or moving side wire anchors.
A cutter suction dredger can advance on its spuds, depending on the spud
arrangements in various ways. Spud systems work on the principle that one spud
is moved while the other is kept firmly in the seabed. Spuds are mounted at the
rear of the dredger and forward movement is achieved by swinging on one spud
until the other is ahead, then dropping it and lifting the first spud. In recently
built large rock cutter suction dredgers, the working spud is mounted in a mobile
carriage which allows the dredger to advance over a length of approximately 6 m
(+ 20 ft) without changing the spud. When the carriage reaches the end of its
stroke, the auxiliary spud is dropped, the working spud lifted and the carriage is
moved to its advanced position. Hence a new cycle can start after dropping the
working spud and lifting the auxiliary spud.
The cutter suction dredger requires side wires used for movements and control of
the dredged head. In hard material a considerable force is taken in the side wires
and the largest rock cutter suction dredgers have a side pull of about 300 [metric]
tons. Anchors must be, when the side wires are at an angle of 30 to 40 degrees to
the perpendicular, moved forward to a new position.
The cutter suction dredger is connected to the shore by its floating pipeline and so
as to allow the dredger to advance forward as far as possible without having to
stop dredging to avoid breaking the pipeline and either extend or move it.
Cutter suction dredgers are rated by the diameter of their discharge pipes and the
power on the sandpumps and on the cutterhead.