First electric US tug challenges European hegemony

Built in the US, the owner has hinted it will be the first of more sister tugs to be developed by Crowley.

Tug owners and operators are navigating a complicated path as they consider how to power their new investments with pressures from all quarters to improve the operational efficiency and environmental impact of these workhorses which, by their nature, require power greater than most vessels of a similar physical size.

Various options are emerging for tug owners weighing up which ‘alternative fuel’ to adopt, of which all-electric is just one, considerations including the vessel’s operating profile.

European shipyards and Canadian naval architect Robert Allan have been among those leading the way with battery-powered and hybrid tugs, and eWolf, built by Master Boat Builders in Coden, Alabama, meeting Jones Act requirements, could potentially lead to alternative fuel tug construction of this type extending beyond the usual European area of expertise for customers in the US.

The industry is always keen to describe the benefits of reducing environmental impacts and Crowley says eWolf will generate 178 tons less NOX, 2.5 tons less diesel particulate, and 3,100t less CO₂ over its first 10 years of operation, the equivalent of removing 350,000 gallons of ‘gas’ from use using ABB’s integrated electrical propulsion system. Previously published information said tug would replace one that consumes more than 30,000 gallons of diesel annually.

The vessel was designed by Crowley’s own engineering services team and developed in collaboration with federal, state and local government partners. It will operate at Port of San Diego, where the shoreside infrastructure includes a microgrid charging and storage station with operations expected to begin in spring 2024.

Earlier published specifications of eWolf indicated a vessel of 24.9m length with a beam of 12.1m and design draught 5m.

The 6.2MWh main propulsion battery drives two azimuthing thrusters via 2,100kW motors with an estimated bollard pull of 70 short-tons and vessel speed 12kn. It is also equipped with two 300kW generators for long transits.

The specification also includes two Markey Machine DEPC-48-50HP electric render/recovery towing winches located forward and aft.

Crowley lists two other tugs currently operating in San Diego – the ASD tug Tioga and Voith Schneider cycloidal tug Scout.