Rolls-Royce has received an approval in principle (AIP) from the US classification society ABS for its new hybrid propulsion system for tractor tugs.
The AIP was granted following an evaluation of the world’s first hybrid tug – designed by Jensen Maritime – which Nichols Brothers Boat Builders will deliver to Baydelta Maritime in San Francisco, California, in February 2019.
The vessel will be the first tug boat installed with the Rolls-Royce hybrid propulsion system.
“Our long-standing partnership with Baydelta Maritime and close cooperation with Jensen Maritime, Nichols Brothers and ABS has paved the way for an innovative, environmentally-friendly hybrid tug capable of safe and reliable operation and maximum bollard pull,”
says Griff Lane, Rolls-Royce’s SVP Commercial Marine, Americas.
“The Rolls-Royce hybrid system enhances the tug’s escort capability – providing unsurpassed assist support to the ultra-large containerships that operate from US West Coast ports.”
The Rolls-Royce Hybrid Propulsion System consists of Power Take-In (PTI), electric motors, and main propulsion engines connected to Rolls-Royce azimuth thrusters, allowing vessel to operate in either a diesel-mechanical, diesel-electric or boost mode configuration.
“The key benefit of a hybrid configuration is that it reduces the power requirement,” says Lane.
“Typically, a tug the size of the Baydelta vessel would need a power output 2,500kW.
‘The hybrid arrangement allows operators to achieve the required bollard pull from a smaller engine. It provides greater operational flexibility which allows for the system to provide improved fuel efficiency, redundancy, and reduced emissions.”
The hybrid arrangement provides power to US255 azimuth thrusters with ducted fixed pitch propellers that can be rotated 360 degrees around the vertical axis – an arrangement that optimises omni-directional thrust and manoeuvrability as well as providing improved crash stop capability.