Hybrid Propulsion System

A hybrid propulsion system developed for fast ferries with focus on low weight, and high flexibility in location of the components.

The hybrid system replaces the aux.generator sets for the hotel load, achieves better utilization of the main engines and  are able to operate purely electrical in zero emission operations. The batteries can be charged from shore connection or directly from the main engines.

The hybrid propulsion system is available in 3 versions

Compact PTO:

A small generator system, ideal for retrofits and vessels with limited space for hybridisation. The goal is to reduce NOx emissions and maintenance, and achieve fuel savings by removing the aux.generator sets used for hotel load and improve utilization of main engines.

Compact PTO/PTI:

A small hybrid system, ideal for vessels that need some degree of electric propulsion.  The same properties as Compact PTO, but it can also operate solely electrical for short periods of time. Charging by use of shore power might offer larger fuel savings.

Long range PTO/PTI:

A hybrid system with extended battery capacity and more powerful electric machines. Ideal for vessels that need to operate with electric propulsion for longer periods at reduced speed. Properties as for the Compact PTO/PTI, but with a significantly longer endurance in electrical mode. Significant fuel savings can be achieved, provided charging of the batteries from shore connection.
All 3 models use a distributed DC system for optimal flexibility for installation of the components below deck.

Battery charger for shore power can be installed on board or at the quay, depending on what is most suitable.


BostekHybrid Version POWER RANGE:
Elect. power


System weight* Battery






Zero emission


El. machine


 Compact PTO 50 265 kg Customized 750VDC Optional No G2
 Compact PTO/PTI 50 265-350 kg Customized 750VDC Optional Yes G1, G3
 Long range PTO/PTI 100-500 From 400 kg Customized 750VDC Optional Yes G1, G3
*System weight per shaft line includes electric motor, drives, control panels and filter. Assumes 50kVA supply to MSB