UK Royal Fleet Auxiliary’s Tide Class Tankers

GE Delivered Its Hybrid-Electric Propulsion System to the U.K. Royal Fleet Auxiliary’s Fleet of Four Tide Class Military Afloat Reachand Sustainability Tankers

GE’s system allows the fleet to achieve increased efficiency and operational flexibility. The project reinforces the trend that more navies are turning to the flexibility of electric and hybrid-electric vessels. Now in service, Tide Class’ role has been perfectly demonstrated as part of the recent Carrier Strike Group exercises.


The UK RFA had a requirement to replace its replenishment-at-sea (RAS) vessels to deliver supplies of fuel and water to Royal Navy ships so they could stay on mission. Known as ‘fast-fleet’ support, they would need the ability to keep pace with Royal Navy’s combat ships on operations –unusual for a conventional, slower transport tanker -and operate within a forward, military environment to provide ‘reach’ and ‘sustainability’ for the combat group.

Needing to be energy-efficient and capable across a range of duty cycles, and speed and power profiles, configuration and output of electric power on the ships would be more significant than on a conventional transport tanker.

GE Power Conversion set about configuring the electric propulsion power system within the hybrid electric CODELOG power and propulsion architecture for the 200 meter-long tankers. The system was conceived to be flexible enough to provide high-performance electric power for different modes. Fast forward to today, GE has successfully delivered its electrical power and propulsion system for all four ships, through successful sea trials and proudly seen them enter into service.

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As a hybrid electric propulsion configuration, GE’s technology enables the tankers to operate at the most energy-efficient form of propulsion for each operational scenario.

Designed for fuel efficiency, GE’s electric motor can provide power to the propellers in addition to the propulsion diesel engine, which is used when higher speeds are needed. It can also conversely harness the power from the engine shaft to generate electricity and power the electric equipment on board when the tanker operates at moderate or low speeds.

  • 2.4MW induction motor/generators
  • SeaPulse AFE (active front end) drives
  • Thruster motor and soft starter
  • LV switchboards (690V)
  • Design, system engineering and commissioning to IMO and naval standards, for operation in harsh environments
  • Training to RFA staff on operating equipment at GE’s Marine Power Test Facility.

tide class

Fuel-efficiency, lower emissions: Using an electric propulsion motor powered by the ship’s generating sets to run the propeller can save fuel, reduce emissions.

It can also reduce maintenance costs of the main engines since the generating sets are already running to meet electrical power needs on-board the vessel.

Decades of expertise, fleet commonality: Similar to hybrid and electric cars, we have seen an increase in the world’s navies using hybrid propulsion systems for enhanced fuel efficiency. GE supplies electric ship technology to 15 navies on nearly 120 ships, including the majority of the Royal Navy’s large ships, providing commonality for operations and support.