Van der Velden® FLEX tunnel on 'Rhenus Diusburg'

Van der Velden® FLEX tunnel

FLEX Tunnel

The Van der Velden® FLEX Tunnel is a retractable tunnel, which can be set into operation only when necessary.

When a ship is loaded and sailing in deep draught, the FLEX Tunnel is retracted and embedded into the vessel hull. In this situation, the water flows into the propeller unobstructed. In comparison to a conventional tunnel, the flexible retraction of this system significantly reduces the overall resistance of a vessel.

When a ship sails at shallow draught (e.g. with low water levels) , the propellers are not fully covered in the water, which makes them function less (high resistance and low velocity). This is when the FLEX Tunnel needs to be deployed. This guarantees water inflow to the propeller, making a ship operational for a longer period of time. With the FLEX Tunnel a vessel can sail longer on shallow waters and/or can take more cargo. The risk of not being operational during shallow water periods is significantly reduced.

The emergence of the FLEX tunnel goes back to 2010, when Damen Marine Components developed the concept together with research institute DST Duisburg. The retractable tunnel was extensively tested at different water depths and speeds in various configurations, also measuring resistance reduction when the tunnel is deployed. There was one clear conclusion;the FLEX Tunnel provides considerably higher operational efficiency for the entire vessel.

For the integration of the FLEX Tunnel, the total hull design should be customised. This innovation is therefore not suited to existing vessels.



  • Propulsion efficiency improvements of approximately 10%
  • Less resistance
  • Considerable fuel saving
  • Good manoeuvring at low speed and shallow draught
  • Smaller propellers and lower engine capacity required
  • Longer operational at shallow draught


  • Newbuild inland vessels


Van der Velden XR rudders (package)

Van der Velden® XR Rudder

The XR rudder system is especially developed for optimal propulsion efficiency in combination with first-class manoeuvring characteristics

The design of the rudder trunk is eco-friendly and requires low maintenance.

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2DWK Steering System

The 2DWK is an asymmetrical steering system developed for HD and XR rudder systems.

The 2DWK steering system is suitable for every type of vessel, but it is mainly designed for inland vessels.

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Maintenance friendly 4DWKK steering gear is mainly designed for inland vessels.

4DWKK steering system

The 4DWKK is a reliable asymmetric steering system, specifically engineered for the Van der Velden® HD and Van der Velden® XR rudder systems. The 4DWKK is specifically engineered for twin screw inland vessels with four rudders.

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The system was developed with the latest technologies and is in accordance with current and expected regulations.

SP2700 control system

SP2700 is a real-time redundant digital steering installation with a control and alarm system.

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The HP 7000 can be used in combination with the latest autopilots.

HP7000 control system

HP7000 is a proportional hydraulic installation This steering installation is completely independent of the electrical system.

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