Rolls-Royce Gets AiP for Hybrid Tug Propulsion System

Technology company Rolls-Royce has received an approval in principle (AIP) from classification society ABS for its hybrid propulsion system for tractor tugs.

The AIP was granted following an evaluation of the world’s first hybrid tug, a vessel designed by Jensen Maritime.

To be delivered by Nichols Brothers Boat Builders to Baydelta Maritime LLC in February 2019, the vessel will be the first tug boat installed with the Rolls-Royce hybrid propulsion system.

ABS considers the Rolls-Royce hybrid system is, in principle, compliant with ABS Rules for Building and Classing Steel Vessels Under 90m (2018); ABS Advisory on Hybrid Electric Power Systems (2017); and ABS Guidance Notes on Review and Approval of Novel Concepts.

“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. The Rolls-Royce hybrid system enhances the tug’s escort capability, providing … assist support to the ultra-large containerships that operate from US West Coast ports,” Griff Lane, Rolls-Royce SVP Commercial Marine, Americas, said.

The Rolls-Royce Hybrid Propulsion System consists of Power Take-In (PTI), electric motors, and main propulsion engines connected to 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. 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,” Lane explained.

Rolls-Royce will supply all electric motors, shaft generators and a power management and control system. The hybrid arrangement provides power to US255 azimuth thrusters with ducted fixed pitch propellers that can be rotated 360 degrees around the vertical axis. This arrangement optimizes omnidirectional thrust and maneuverability as well as providing improved crash stop capability.