The concept of "hybrid tug" is getting a whole new definition with an innovative new tug under construction at Turkey's Uzmar Shipyard for the Danish Port of Aarhus. From the outside it looks very similar to other Robert Allan-designed tugs built at the Uzmar yard. The tug, to be named Hermes, is 30.25 by 11.75-metres and has a Young Ice I Class Notation.
In the engine room and in the thruster rooms of the azimuthing stern drive (ASD) tug, the innovations are revealed. A pair of Cummins QSK60 IMO stage II compliant engines, each send 2,700 hp (2,013 kW) to the Schottel Rudder Propellers type SRP 430 azimuthing thrusters.
Most ASD tugs have the thrusters in a separate room, so also does the Uzmar tug, but an additional drive shaft links the port and starboard thruster units.
The remarkably simple innovation allows one engine to be shut down, when the tug is not actually handling a ship, while the other engine provides adequate power to both thruster units. Since harbour tugs spend considerable time running at low load levels between docks, this can result in significant reduction in emissions, fuel costs, and, over time, maintenance costs.
With both Cummins engines powering the fixed-pitch, nozzled, 2.5-metre props on Schottel thrusters, the tug will have a 12.5-knot free-running speed and a 65-tonne bollard pull.
In another configuration, the power of the starboard engine can be dedicated to a large fire pump mounted to the front end of the engine. At the same time, the power of the port engine is committed to both of the azimuthing thrusters. This gives the operator full manoeuvring control of the tug while holding it in the best position for firefighting. The harbour tug becomes a serious asset for combatting waterfront fires.
"We can confidently say that this project will be a real revolution in towage operations and a great milestone for our green tug solutions," Mr, Noyan Altuğ, CEO of Uzmar, has said of Hermes.
Delivery is anticipated for the summer of 2021.