New Low-emission Hybrid Azistern Tug Design

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

OSD managing director Michiel Wijsmuller said, “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 m LOA / 50 BP Azistern-e is generated by two 970kW variable speed gensets and is supported by two 400kWh lithium battery packs. The low-emission tug can be delivered compliant with IMO Tier 3 requirements with an after-treatment system suitable for ECA areas, and is also equipped with an innovative energy management system. The uniform and perfectly optimized loading of the propulsion system ensures low maintenance and fuel costs. Transient sailing and maneuvering can be performed using the batteries with zero emissions.

OSD said the Azistern-e is highly maneuverable, 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. 

As a result of its podded drive and the double elastic mounting of its gensets, the MLC-compliant vessel will also provide high comfort level for its four-man crew.