Hybrid Propulsion - Diesel & Electric

A perfect pair? The benefits of utilizing diesel & electric together

A perfect pair? The benefits of utilizing diesel & electric together

In the continued drive for greater fuel efficiency and reduced emissions, Caterpillar has developed a hybrid propulsion system, ideal for tugboats or many other marine applications. The Cat Hybrid Propulsion System brings a great deal of flexibility to the vessel, giving captains several options in how they operate their tug. Here, Emil Cerdier, the sales manager for propulsion in the Americas, introduces the Cat Hybrid Propulsion System and its capabilities.

“The Cat Hybrid Propulsion System is a fully integrated system that’s designed to fulfill the contractual requirements of a tugboat or many other applications, and also optimize operational costs based on where that vessel is going to spend the bulk of its time.”

The Cat Hybrid Propulsion System can be developed as stem-to-stern solution, with a pair of primary diesel engines connected to the vessel’s azimuth drives. In addition to the diesel engines, the Cat Hybrid Propulsion System includes VFD controlled booster motors, which are also tied to the azimuth drives. The booster motors are powered by generator sets and/or batteries and the load balancing and switching between operation modes are handled in a highly optimized control system.

Popular power options for the Cat Hybrid Propulsion System include Caterpillar’s highly esteemed 3500 marine power series, and a suitable selection of generator sets.


Interested in fuel savings, lowering your maintenance costs and reducing your emission output? Meet our new Cat Hybrid Propulsion System.

But what is the benefit of utilizing diesel and electric together?


“The idea is that you can switch between them and only have as much power online as is needed for a certain operation.”

For example, if maximum performance is needed from the azimuth drives, a captain can combine full power from the diesel engines with the booster motors to get top bollard pull. If, though, the vessel is in transit or in standby, then the main diesel engines can be shut down and the smaller generators used to create enough thrust. And if conventional tugboat capabilities are desired, the diesel engines can be used to power the azimuth thrusters without the booster motors. This ability to switch on the fly offers obvious benefits, including:

  1. Increased fuel efficiency – In transit or standby, the vessel can run its smaller generators at a higher load, getting more out of every drop of fuel.

  2. Reduced running hours – With additional power options on the vessel, captains can protect their primary engines from unnecessary wear.

  3. Reduced maintenance costs – Caterpillar’s C-series of generator sets are smaller than the 3500 engines, which means they are easier to service, and cost less to do so. Captains can take advantage of this by prioritizing generator usage whenever possible.

  4. Reduced emissions – Better fuel efficiency and higher average engine load means lower emissions.


The Cat Hybrid Propulsion System gives every captain what they want – options. And with more options comes more performance and more efficiency.



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We know not every question can be answered on a website, so please let us know what's on your mind. We'll be happy to schedule a one-on-one conversation with you to share more specific details about hybrid propulsion and its advantages. We want you to have all the facts so you can make the right decision for your vessels.

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