How Our Hybrids Work
An engineering breakdown of Hybrid Marine's parallel hybrid driveline architecture, component integration, and the six versatile operating modes.
Single Motor Hybrid Driveline Components
The diagram and reference breakdown below show the core assembly of a standard single-motor parallel hybrid setup mounted to a marine engine and gearbox.
| Item | Description |
|---|---|
| A | Standard Marine Gearbox (PRM 150 shown). Connects via bell housing (B) to engine (C). Output connects to soft coupling and propeller shaft. |
| B | Gearbox Bell Housing |
| C | Marine Diesel Engine |
| D | Gearbox Oil Cooler |
| E | Liquid-Cooled Brushless Motor/Generator: The core hybrid unit. Positioned above the gearbox and connected via pulley and belt arrangement. |
| F | Motor/Generator Mounting Bracket: Secures assembly to the gearbox and bell housing. |
| G | Output Pulley & Toothed Belt: Inserted between gearbox output flange and shaft coupling to drive the motor/generator. |
| H | Protective Belt Guard |
| I | Shaft Clutch (Optional): Disconnects the propeller shaft so the hybrid can operate as a stand-alone generator (or replaced with a boost alternator on canal craft). |
System Overview & Basic Operation
Core Operational Cycle
- Electric Cruising: With the diesel engine off and gearbox in neutral, the electric motor drives the propeller using battery power. Speed and direction are managed by the electronic controller.
- Diesel Operation & Generation: When battery reserves deplete or higher power is required, the diesel engine is started and put into gear. The controller senses engine ignition and switches the electric motor into generator mode to recharge the battery bank while underway.
- Automatic Mode Switching: Once recharged, stopping the engine causes the controller to automatically revert back to electric drive readiness.
- Higher Engine Efficiency: Running the diesel engine under a combined load (propeller + high-output generator) optimises specific fuel consumption.
The Six Operating Modes of a Hybrid
Parallel hybrid propulsion systems support six distinct power flows depending on vessel requirements and operating conditions:
Mode 1 – Engine Drive
Conventional diesel propulsion with hybrid systems inactive. The diesel engine drives directly through the gearbox to the shaft, maintaining complete independence from hybrid components.
Mode 2 – Electric Drive
The diesel engine remains off while the electric motor drives the propeller quietly using energy stored in the battery bank.
Mode 3 – Engine + Electric Boost
Both engine and motor combine to drive the propeller. While useful in automotive acceleration, marine power demand is constant; we generally recommend sizing engines for full power needs.
Mode 4 – Engine Drive & Generation
The engine drives the shaft while the electric unit acts as a generator, recharging batteries. Our patented controller dials back generator load at high engine speeds to prevent overload.
Mode 5 – Stand-Alone Generator
With the shaft clutch open and propeller disconnected, the engine and hybrid motor operate as a stationary high-output generator at anchor or in harbour.
Mode 6 – Hydro-Regeneration
Designed for sailing craft under canvas. Water passing over the free-wheeling propeller spins the shaft, allowing the hybrid unit to generate battery power while sailing.
Compare external driveline configurations versus inline flywheel-mounted options.
Parallel Hybrid Types →