Dredging is one of the main marine construction industry that keep the economy running and blooming. As the ships get bigger and bigger, their drafts get deeper and deeper and natural erosion shallows the channel depths, a dredge comes to the help. Another important function of a dredge is useful when hurricanes wash away beaches and where homes get a bit too close to the ocean than they should.
There are different types of Dredges that are suitable under different types of projects. There is a Mechanical Clamshell or a Backhoe Dredge, a Hopper Dredge, Suction Dredge and Cutter Suction Dredges. Some times all types of dredges work together to deepen a channel, widen a beach or build a man made island just like the ones in Dubai.
If rock is involved, Drill boat or Backhoe dredges or Cutter suction dredges are used to first cut or break the rock and remove it from the bottom of the sea and transport it via pipeline or scow / hopper barges out to reefs or other usable land.
If large areas are needed to be deepened with suitable material like sand or mud then just about all types of dredge can be used to successfully deepen the channel, but hopper or cutter suction are probably the most efficient types of dredge that will be used on the projects.
If toxic material is to be handled, then Clamshell Dredges with specially designed buckets are used which minimize spillage and turbidity in the water. The material is put in a scow, which is treated before being dumped in offshore areas.
Dredging is one of those industry which is recession proof as man tries to change the natural environment and nature fights back and tries to go back to the same state. The battle continues and jobs are created. Not many people know about dredging, which has jobs for engineers, surveyors, businessman and entrepreneurs.
It is a very expensive business to be involved in, as almost always it never goes according to the plan due to curves thrown by the nature and deadlines reach their deadends. You can think you have taken all parameters into account but there is always some new that you find and add to your equation.