Everyone knows the biggest ships in the world -–the longest yacht, the most luxurious cruiser ship and the biggest container ship. On the high seas all is fine, but when these ocean behemoths approach port, they need help. To maneuver into harbour they rely on small, nimble and immensely powerful harbour tugs to tow them around. Two new such tugs are currently under construction at the Cheoy Lee shipyard in southern China and are scheduled to enter service with PSA Marine Peru in the ports of Peru in 2022 and 2023.
It's a fascinating sight as a small harbour tug, about 24 meters long and 11 meters wide, has a 300-meter-long and over 50-meter-high container ship on the end of a line, towing it into port. “The impression is somewhat deceptive,” explains Andreas Müller-Hirlinger, a harbour tug expert at Rolls-Royce Power Systems. The harbour tug isn't towing the ship into port, it's stabilizing it. Even so, the harbour tug – which looks small by comparison but seems huge when you stand beside it – needs loads of power to do its job. And this power is delivered by mtu Series 4000 engines.
Extreme dynamics of the engines impress
These produce a full 2,240 kW in each of the two tugs Robert Allan design currently being built. Aside from pure oomph, a key feature of these engines is their power flexing capability. The high-revving 16-cylinder mtu engines with the type of designation '4000M63L' achieve their full power output in a matter of a few seconds, meaning they can accelerate extremely quickly and respond nimbly to the movements of the vessels they are maneuvering into the port
The new harbour tugs have a bollard pull of 70 metric tons, meaning that the harbour tug has the same power it would take to lift 70 metric tons off the ground. The mtu engines do this by transmitting their power directly to two Schottel directional propellers below the waterline. One of the two harbour tugs is equipped with Schottel's innovative Sydrive-M system which combines two azimuth thruster propellers – one to port and one to starboard – in such a way that both props can be powered by just one mtu engine, reducing engine operating hours and thus maintenance costs, fuel consumption, CO2 emissions and other pollutants.
Goal: The establishment of a sustainable maritime ecosystem
William Revilla, Project Director at PSA Marine Peru, puts special emphasis on the desire to maximize the sustainability of his harbour tugs. “Sustainability is important to us. We are constantly looking for solutions to operate our vessels as efficiently and sustainably as possible. The partnership with Rolls-Royce Power Systems and its local partner Detroit Power Systems Peru to install mtu engines on our vessels is one of our key efforts towards building a sustainable maritime ecosystem”, Revilla said.
These two new harbour tugs, PSA Tallan and PSA Wayra, will soon be added by 2022 and 2023 to the existing fleet to reach a number of 18 harbour tugs operating in Peru.