Posted on September 13, 2022
Efficient hydrodynamic rudder system for methanol-ready boxships
Full spade rudders with asymmetric leading edge and bulb in the wake of the propeller to further enhance flow along the rudder and reduce turbulence, will enable considerable fuel savings for two new 7,100 TEU container vessels that Danaos Shipping aims to take in operation mid 2024.
Damen Marine Components (DMC) will provide one Van der Velden® Atlantic Rudder for each vessel. These rudders are known to cause minimal drag thanks to their slim design. For these container vessels, Asymmetric Rudder Technology (ART) will be applied in the design of the leading edge of the rudder. A rudder bulb in the wake of the propeller axis, further improves the hydrodynamic properties of the rudder configuration.
Greek ship owner company Danaos Shipping ordered the two 7,100 TEU feeders at Dalian Shipbuilding Industry Co, the yard will deliver these vessels during the second and third quarter of 2024. The vessels will be methanol fuel ready and will comply to IMO Tier III emission standards and Energy Efficiency Design Index (EEDI) Phase III. Length between perpendiculars of the two identical vessels is 255 meter, with 42.8 meter breadth, 12 meter design load draught and a design speed of 20 knots. DMC will provide the tailor designed rudder for each one of the vessels, measuring 61 square meter and generating 3300 Kilonewton meter of torque.
As the propeller in forward thrust has a fixed rotation direction, the asymmetric leading edge will improve the water flow by directing the turbulent water along the rudder blade more efficiently. Even more hydrodynamic optimisation is achieved by the bulb. In the wake of the propeller axis, turbulent water can circle and cause vibrations in hull and rudder. The rudder bulb is positioned right behind the center of the propeller and eliminates this turbulence to create a better flow along the rudder blade. A stable and directional water flow generates more thrust than turbulent water.
The advanced rudder technology adds to the sustainable ambition of the shipowner and charterer to operate vessels that cause minimal emissions. The choice for a methanol ready design expresses this ambition. Reducing drag, exemplified by the application of ART Atlantic Rudders with Bulb allow further fuel and emission savings.
“These vessels are at the forefront of new technology,” says Danaos CEO Dr John Coustas. “With this order Danaos will continue to maximise efficiency with a focus on creating value for our shareholders.” The two new container feeders add to the fleet of 71 container vessels, ranging from 2,200 up to 13,100 TEU (Twenty Foot Equivalent Unit – one standard container).
“We are proud to have been selected by Danaos as partner for reaching their targets of improved operational efficiency and reducing the environmental footprint of their fleet” says Wim Knoester, Commercial Director of Damen Marine Components.