Propulsion Improvements for Shallow Water Operation

By Keith Henderson at October 25, 2011 05:56
Filed Under: Company News

Operating a vessel in shallow or unpredictable depths of water is a hazardous procedure. On one side safety requires erring on light loading, yet commercial considerations dictate having a fully laden vessel. As many of the navigable inland  waterways of Europe are rivers, levels fluctuate with the seasons and affect loading levels of inland waterway barge traffic.

To improve propulsion efficiency under shallow water conditions, barges often use a tunnel duct to ensure the propeller receives sufficient water to provide propulsion however this brings a penalty in lost efficiency when operating in deeper water. In Holland alone, shallow  water effects  are estimated to have cost $39 million (Euro 28 million) over the last 20 years.


Caption: The retractable FLEX-Tunnel is lowered to duct water flow to the propeller in shallow water conditions.
Image Credit: Van der Velden Marine Systems.

To improve propulsion efficiency under shallow water conditions, barges often use a tunnel duct to ensure the propeller receives sufficient water to provide propulsion however this brings a penalty in lost efficiency when operating in deeper water. In Holland alone, shallow  water effects  are estimated to have cost $39 million (Euro 28 million) over the last 20 years.

A specialist Dutch propulsion company, Van der Velden Marine Systems, has developed a shallow  water propulsion system, together with the German research institute DST (Development Center for Ship Technology and Transport Systems). Called the Flex Tunnel, it is basically a retractable tunnel that allows free water flow to the propeller under normal conditions, yet be lowered in shallow waters to ensure adequate water is ducted over the propeller.
Vessels equipped with this system have smaller propellers and rudders reducing weight and draft, in addition, hull lines can be optimized giving increased loading capacity.

Usage statistics of full-load barge operation estimate that only 15 per cent of voyages are in shallow water therefore the Flex Tunnel offers substantial operational cost savings in lower fuel consumption and fuller loads.

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