---

Offshore Ship Designers (OSD) has designed what it describes as "a powerful, low-emission compact e-tug" to further augment its Azistern series of vessels. Among other roles, the vessel is equipped to deliver harbour assistance.

In a statement, OSD managing director Michiel Wijsmuller commented: "The Azistern-e has the typical low resistance stable hull and all-round visibility that is associated with all Azistern designs. What makes this particular Azistern tug different is that it is driven by a revolutionary podded drive and that it has a flexible and green electro/diesel-electric configuration."

The hybrid power of the 22-metre-long, 50 BP Azistern-e is generated by two 970-kilowatt (kW) variable speed gensets and is supported by two 400-kilowatt-per-hour (kWh) lithium battery packs. The low-emission tug can be delivered compliant with IMO Tier 3 requirements with an after-treatment system suitable for Emission Control Areas (ECAs), and is also equipped with an energy management system.

OSD says the "uniform and perfectly optimized" loading of the propulsion system ensures low maintenance and fuel costs. Transient sailing and manoeuvring can be performed using the batteries with zero emissions.

"The Azistern-e is highly manoeuvrable, and the vessel's power train has a remarkably short reaction time. By using the batteries as a booster, maximum bollard pull can be achieved within seconds. The relatively small size of the engines and the shaftless configuration frees up more space below deck, providing optimum flexibility in respect of the division of space and piping," OSD added.