Hybrid marine drivetrain

A hybrid marine drivetrain for a watercraft, the drivetrain including a driveshaft for driving a propulsion device of the watercraft, an internal combustion engine for driving the driveshaft, a motor for driving the driveshaft, a storage unit for storing energy in a form suitable for operating the motor, and a generator driven by the internal combustion engine for generating energy to power the motor, wherein a drive output of the motor is in direct driving connection with the driveshaft, a drive output of the internal combustion engine is in direct driving connection with a rotor of the generator, and a clutch is provided to selectively couple/decouple drive from the internal combustion engine to/from the driveshaft,

• wherein the drivetrain is adapted to operate in a range of modes including a hybrid mode in Which the driveshaft is driven directly by only the motor, and the motor is powered by the internal combustion engine, the internal combustion engine operating in said hybrid mode in series with the motor with the clutch disengaged to enable the motor and the engine to rotate mutually independently,
• the generator is arranged to power an alternating current power circuit of the watercraft via a power controller;
• and
• wherein when the drivetrain is operated in the hybrid mode the drivetrain regulates engine speed of the internal combustion engine at rotational rotational speeds below, at, or above the operating speed of the electric motor, independently of a rotational speed of the driveshaft, to drive the generator and to thereby supply power from the power controller to said alternating current power circuit, said regulation being performed according to load requirements of the alternating current power circuit and to optimise efficiency of the internal combustion engine.