Damen Shipyards has introduced its Damen Air Cavity System (DACS) that can cut fuel consumption on seagoing vessels by 5% and by between 10-20% on inland ships
Damen R&D engineer Sasha Zverkhovskyi delivered a presentation at the RINA Sustainable and Safe Passenger Ships conference in March about DACS for sustainable passenger ships.
DACS came into being due to a research project conducted at Delft University of Technology in the Netherlands. By maintaining a thin layer of air over the flat bottom of a vessel’s hull, DACS achieves a significant reduction in water resistance, leading to increased efficiency and reduced fuel consumption and, therefore, emissions, Damen explained.
As well as fuel and emissions savings, Mr Zverkhovskyi told Passenger Ship Technology “Reducing the ship’s resistance leads to a lower propeller load and less noise generated by the propellers, which is good for passengers and sea life.”
Other benefits include reducing the negative effect of the fouling on resistance. Dutch-flag vessels can qualify for EIA tax reduction by implementing the system.
Damen said the following components must be integrated into the vessel structure for a DACS operation: bridge control and alarm panel; air compressor; starter/junction box; automated air valves; air pipe work steel and/or plastic; cavitators – transversal profiles on the bottom; skegs – longitudinal profiles on the bottom.
Mr Zverkhovskyi presented two case studies of cruise ships optimised with DACS. Based on the results of towing tank tests, power savings of up to 18% and 5% were achieved for the inland waterway cruise ship and the seagoing cruise ship respectively. While relative savings (%) are higher for inland ships, absolute savings (tonnes of fuel) are higher for seagoing ships as those use much more energy.
Mr Zverkhovskyi made the point that the impact of energy saving is not only on opex but can be also significant when considering capex.
The system is particularly relevant for hybrid and electric vessels, Damen said, explaining that DACS can reduce the energy consumption of ships and by that either reduce the size of the energy storage/generation system or extend the range of a ship. Benefits for battery ships are reduced battery size/weight and charging time.