Parallel Hybrid: Diesel + Single Electric Motor with Energy Storage

This parallel hybrid propulsion system uses standard Twin Disc electronic controls. It’s best suited for short-trip vessels such as ferries, inland waterway vessels, small/medium passenger vessels, harbor service boats, and pilot boats with sufficient shore time to charge batteries, and for vessels operating in restricted areas or zero-emission zones. Twin Disc technology enables implementation into any standard marine transmission.


High Voltage

Data / Command Signals

System Overview

  • Parallel hybrid using diesel and electric power
  • During low-power operation, the e-motor can use excess diesel power to generate electricity
  • In high-demand phases, electric power can boost diesel power
  • Machinery compartments can be located to optimize cargo space or meet class requirements

Marine Transmission

  • Based on standard marine transmission, with same footprint and selection criteria, for worldwide support
  • No trailing pump needed; transmission is lubricated as diesel or e-motor drives it
  • Efficient design minimizes losses


  • Permits power generation through PTO/PTI in forward, neutral and reverse
  • Prevents engine back-driving during electric-only operation
  • Supports all features of QuickShift® transmission

PTI Gearbox

  • Drives transmission primary shaft (same as engine) with MasterClutch™ providing dis-connect
  • Allows for standard speed/smaller e-motor through motor speed reduction
  • Offset to propeller shaft enables installation of large motors
  • Reductions from 1.0:1 to 2.5:1
  • Integrated sea water pump cools transmission during electric propulsion
  • PTO available for onboard hydraulics (e.g., steering pump)

Propulsion Controller

  • Twin Disc standard propulsion controller and operator interface

Hybrid Controller

  • Manages power distribution, interfacing with propulsion controller and high voltage equipment


  • Selection based on application characteristics (torque, installation)

Inverter, High Voltage Equipment

  • Controlled and monitored by hybrid controller

Energy Storage & BMS

  • Selection based on application characteristics

Diesel Engine

  • Not supplied by Twin Disc

Take the next step

Twin Disc specialists are available to work with your technical experts to select the optimal configuration and components for your specific application.

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