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DMC FLEX Tunnel

Sustainable use of the FLEX Tunnel

In the run-up to the project Chemgas Shipping, together with DMC, had the possibilities and efficiency of the application and use of the FLEX Tunnel investigated at the renowned inland navigation research institute DST (Development centre for Ship technology and Transport systems) in Duisburg. This report was presented in January 2017, concluding that considerable efficiency can be achieved by using the FLEX Tunnel.

We talked to Leo van Zon about those savings and the collaboration with Chemgas Shipping.

“More and more ship owners are showing an interest in this fuel-saving innovation.”

Leo van Zon, sales manager Damen Marine Components.

1. Can you tell us something about how this project went for Chemgas Shipping and the products delivered by DMC?

In the run-up to the project, Chemgas had the possibilities and efficiency of the FLEX Tunnel investigated at the renowned inland navigation research institute DST (Development centre for Ship technology and Transport systems) in Duisburg. The report presented in January 2017 concluded that considerable efficiency could be achieved by using the FLEX Tunnel.

DMC helped with the design of the stern in order to determine how big the FLEX Tunnel and propeller should be. After all, a bigger propeller is more efficient than a smaller one. The FLEX Tunnel allows the vessel to sail effectively even with a shallow draught (low water level or unloaded vessel). This model of ship lends itself extremely well to the use of the FLEX Tunnel, because its own weight is high due to the steel cargo tanks. Also included in our scope of delivery; a high-efficiency OPTIMA nozzle, a hydrospoiler and, of course, the latest developments in rudder technology (XR rudder profile). To top it all, all A-ships have the BOSS™eco panel on board, which shows the crew the effect that rudder movements have on fuel consumption.

2. Why did you specifically choose the Van der Velden® FLEX Tunnel system?

A gas tanker is relatively heavy and therefore usually has sufficient draught, so you can incorporate a bigger propeller and achieve higher efficiency. During normal operation (95% of the time), the FLEX Tunnel ensures sufficient water flow to this large propeller with a shallow draught, with the benefit that the traditional tunnel shape we are all familiar with is superfluous.

This system also gives a ship designer the freedom to create the ideal stern. Reducing CO2 emissions played a part in this shipping company's decision to choose for FLEX Tunnels. The FLEX Tunnel is not called FLEX Tunnel for nothing, because the length of the flap of the tunnel can be flexibly chosen to determine the minimum draught at which the ship can still operate.

3. An interview was recently published on the fuel savings achieved by the Rhenus Duisburg compared to its sister ship Rhenus Lünen on the same route. Can you briefly describe what was discussed in this interview and why it is important?

In this interview, Herbert Berger, Managing Director Rhenus Schiffsmanagement, used design, tonnage, journey time and fuel consumption data from more than 200 trips to answer some questions about his operational experience with the Van der Velden® FLEX Tunnel. Mr Berger explained that the FLEX Tunnel system on board the Rhenus Duisburg directly reduces fuel consumption by 9% in certain sailing conditions with a single operation. Measured over the last few years, the vessel achieved an average of 11% fuel savings in daily operation on the route from Rotterdam to Wesel compared to its sister ship Rhenus Lünen. This corresponds to a reduction of 277 tonnes of CO2 per year.

As the Rhenus Duisburg was the first vessel to be equipped with the FLEX Tunnel, these results are extremely valuable for the further promotion of this system. Of course, the studies by DST produced indicative savings percentages, but the results of the Rhenus Duisburg are the first practical results that actually prove the system.

4. How will this product develop in the future?

We expect the Van der Velden® FLEX Tunnel to become the new standard for inland navigation vessels. More and more ship owners are showing an interest in this fuel-saving innovation; market confidence is growing. Let's not forget that the past year has been marked by very low water levels, so much so as to warrant coverage by the national news! Indirectly, the shortage of river transport has caused a lot of damage to the European economy. It demonstrates the power of this mode of transport, but also that something needs to be done to ensure there are sufficient modified vessels to keep the transport flow going, even in the event of repeated low water levels. The FLEX Tunnel system is simply the very best available in this field. Both in terms of overall efficiency, thanks to the use of large propellers, and for enabling vessels to operate at low water levels with smaller propellers.