The Green Tug Project – Energy Efficient Design for Workboats

In November 2011 Iskes Towage & Salvage took its first Damen tug into operation: the ASD 2810 ‘Argus’. Pleased with its capabilities, Iskes decided to have Damen Shipyards Hardinxveld build a further two harbour tugs: the revolutionary ASD 3212 ‘Green Tug’, designed by Iskes and Offshore Ship Designers to reduce CO2, SOx and NOx emissions by 30%. The first contract was signed at Europort 2011 (Rotterdam) by managing directors Jos van Woerkum (DSHa), Jim Iskes and Michiel Wijsmuller (OSD). The tugs will be delivered by mid 2013.

Since 2009, Iskes strives to reduce CO2, SOx and NOx particles, the ultimate goal being zero emissions. Triggered by the commitment of the ports of Rotterdam and Amsterdam to the World Ports Climate Initiative, Iskes teamed up with Offshore Ship Designers to develop a tug with 30% emission reduction. Other stakeholders included research centre MARIN and tug operator SMIT. Currently, the Green Tug Project is in the final, detailed design stage. This is carried out in close cooperation with Damen Shipyards Hardinxveld and Damen Research, especially when it comes to propulsion and bollard pull.

Environmental economy

DSHa’s Jos van Woerkum says: “The Green Tug has several similarities with our Damen E3 project, that aims for environmentally friendly, economically viable and efficiently operating ships. Secondly, this is the first time Damen is building a vessel that it has not designed in-house. DSHa is known for its Multi Cats, Shoalbusters and Patrol Vessels. However, the Damen ASD 3212 design neatly fits within the OSD-Iskes format of the Azistern 3270. In addition, we work in an ‘open calculation’ format. Cost control is important if this design is to be a commercial success. However, with this project there’s no fixed price! The Green Tug’s development is more important.”

Characteristics

The Green Tug’s azimuth thrusters, bow thrusters and winches use diesel-electric propulsion. In order to reduce emissions while mobilising to a job the tug will sail on battery power. The energy management system ensures that the master of the tug always gets the power he needs regardless if the power comes from batteries or from one or more diesel generators. When sailing at cruising speed only one generator is used, this cuts down on fuel consumption and maintenance. The vessel will have 70 t bollard pull and is equipped with a double drum, creating an independently controlled forward winch system. The idea is to pay out two tow-wires at the same time and control each wire independently. This is very practical when manoeuvring in narrow spaces.

‘Jos and Jim’

“Although Jim and I never did business before, we’ve known each other quite well for a long time and understand each other’s’ needs”, says Jos van Woerkum. “A man, and a client, like Jim Iskes goes well with our type of organisation. He’s very straightforward, knows what he wants and is not afraid of participating in new developments. He’s an experienced captain and as a ship-owner he’s bursting with ideas. In short, a real entrepreneur. Our own experience is added to his. With every new vessel we try to improve our standards. We sail along when the vessels is doing its job and evaluate if it does what we designed it to do. We always try to put our knowledge of clients and ships into our design and production standards. Standardization is of course one of Damen’s basic strengths. So, why did we decide to build the Green Tug, this non-standard project? Because it’s a real innovation, a chance to co-create a future standard and, of course, because it’s work for our shipyard. My message is: Damen can build more than standard vessels and at the same time deliver added value because of our standards. We’re proud to participate in Iskes’ project.”

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