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IJmuiden-based Offshore Ship Designers (OSD) has been contracted to develop the design of a low-emission diesel-electric harbour tug for Iskes Towage & Salvage, based in the same port city.

The 32-metre loa tug will have a bollard pull of 70 tonnes and will be powered by three diesel gensets driving electric motors mounted over azimuthing propellers aft and a Voith in-line thruster forward.

The Azistern 3270 tug is a further development of the low-emission Azistern series developed by OSD. It is expected to reduce emissions by 30 percent compared to conventional, similar-sized harbour tugs currently in service.

Michiel Wijsmuller, managing director of OSD, said, “The design and demand for this low-emission tug stems from our successful work developing the zero-emission Green Tug design. Iskes was one of the key partners in that project. We can see the market is not yet ready for fuel cell power for harbor tugs, but we can take from the development work other aspects of the design which minimise emissions. This vessel will have a very refined and efficient hull form and a sophisticated power management system which will ensure that the gensets work always at their best efficiency.”

Key points of the design brief are a relatively large deck crane to enable the tug to do maintenance work for wind farms at sea, electrical winches, low resistance and low-wash hull form and accommodation for seven crew.

Offshore Ship Designers Group (OSD) delivers naval architecture and marine engineering skills to the shipping and offshore energy industries. It provides feasibility studies, conceptual and detailed designs for tugs and offshore support vessels of all types.

The company's head office is based in IJmuiden, Netherlands, and it also has offices in Montrose, York, Appledore, Shanghai and Singapore.

Image: Azistern 3065 tug