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Hybrid Propulsion – the future today

Submitted onOctober 23, 2009 4 Comments, join the conversation

built by Cantiere Navale di Pesaro, The Naumachos line of yachts are devised for travelling around the world

Alex Clark explains why Hybrid Propulsion on yachts provides more benefits besides lowering environmental impact. But rather than just stick to rhetoric, he shows us how one yard decided to take action.

The Naumachos line of yachts, built by Cantiere Navale di Pesaro, is the result of a great love for the sea and for the environment.

It is the spirit dedicated to discovery that is behind the development of the Naumachos line of explorer yachts: solid and able to withstand any weather conditions with great autonomy, while offering the comforts of luxurious accommodations. The Naumachos line of yachts are devised for traveling around the world, for living at sea while respecting the environment in total freedom and complete safety.

The philosophy behind the design is the idea of creating a comfortable home that will stand up to extreme conditions. The CNP line of explorer yachts is now available multiple models: Naumachos 82′ Naumachos 105′ Naumachos 115′.

CNP Shipyard’s product diversification is the result of over 55 years of experience in high technology shipbuilding. This knowledge has been flawlessly transferred from commercial builds over to its yachting lines resulting in top pedigree and reliability, combined with Italian style.

Every yacht is customized for each specific buyer: interior design with furnishing lines materials, machinery equipment engines, electronics packages, even hull color. And now CNP is proud to offer the optional Hybrid Propulsion package. Alone, with the normal propulsion package, the Naumachos line already operates with a very low consumption of 50 liters/hour while operating at 10 knots with a 6,000nm range. Adding the Hybrid Propulsion system only enhances the fuel efficiency while decreasing the carbon footprint the yacht leaves on the environment.


The Hybrid Propulsion chosen by CNP is a new generation of electrical machines and
systems made by Pronaves. This system will first be installed on the Naumachos 82’ being delivered in 2010. A brief description of the system is as follows:

The optional hybrid propulsion features an electrical machine coaxially mounted to the
diesel motor that can function as a motor or as an electric generator. When the electrical machine is connected to the diesel motor, it receives its energy from the generator which normally furnishes energy for all of the boat’s electrical services. By doing so, it adds torque and increases power to the diesel motor. The electrical machine can also work by itself, without the diesel motor, and can be used in place of APS in the event of a breakdown or during maintenance. Furthermore, when the electrical machine is connected to the batteries, there is sufficient energy to provide total power for multiple hours at low speed in order to navigate through environmentally sensitive marine areas where diesel power is prohibited. An interesting application of the hybrid motor is to allow the electrical machine to function as a generator during navigation. In such a way, the main diesel motor supplies propulsion as well as the electric power needed by the boat without having to use the expensive and excessive power provided by the gen set. When the boat is at anchor, this electrical machine can act independently and replace the diesel generators to provide power and stabilization to the entire yacht with zero emissions.

The final result is an increased cruising range, with a decreased impact on the
surrounding environments.

Pronaves who has developed this system is an engineering and scientific research society established for the purpose of improving naval propulsion by introducing a new
generation of electrical machines and focusing on a new way to use renewable
energy. The society’s research is assisted by experienced men of the sea and by the
highly qualified support of the Electronic Engineering Department of the University of
Rome. This department works closely with Pronaves and has an agreement for the
mutual exchange of personnel and information.

The main activity of this consortium consists of planning, constructing, and
experimenting with synchronous electrical permanent magnetic machines with high
torque and low revolutions. These machines are controlled by a newly developed power
electronics that adapts itself to the requirements of navigation.

The electrical machines from Pronaves operate from a few kW to 400 kW. Within this
range there is a variable torque from 2500 to 10000 Nm. This allows the machines to
rotate from a few revolutions as required by the movement of the rudder and the
stabilizers to hundreds of revolutions for effective propulsion.

These electrical machines are designed for direct propulsion. More than one machine can
be mounted directly on the same axis and can supply as much power as needed. The
machines are mounted directly on the axis of the propeller. This assembly is possible
even if the drive of the axis already has an existing diesel motor. The combination of the
two results in a hybrid propulsion.

These machines can resolve the problems associated with the movement of the rudder
and the stabilizers at zero speed, unlike traditional mechanical controls that require high
power and produce significant noise. The same system can also be applied to the
windlass and any other apparatus that might require vertical or horizontal mechanical

Why Hybrid?
Usually when you explain the benefits of a Hybrid Propulsion system saving energy and
reducing pollutants emissions are at the forefront. This is because the Hybrid System
requires significantly less continuously variable power for the thermal engine for the
same number of turns. The consumption and pollutant emissions of a thermal engine
depends on the speed and power input of the yacht. The Hybrid System, in its various realizations, tries to optimize the operation of the thermal engine resulting in reduced
emissions and fuel consumption.

Hybrid Propulsion on yachts also has other purposes and provides other benefits besides
lowering environmental impact:

  • The Pronaves Hybrid System reduces the space occupied by the engine room and
    is much easier to install thus having a clear economic advantage for the manufacturer.
  • The Hybrid System is generally formed by a diesel engine and electric machine
    mounted directly on the propeller shaft (direct drive). The obvious advantage here
    is that the machine can be operated by the electric motor or electric generator. In
    fact when you are cruising, you can use the diesel engine for propulsion and the
    electric generator to provide electricity on board, allowing you to hold the
    traditional generators and thereby saving in maintenance, fuel and pollution.
  • Another example of applying the Hybrid System would be for navigating at a
    slower speed, where you would use the electrical machine as the main motor, and
    use only the generators to navigate and power the house resulting in a much
    quieter operation with less vibration versus the regular diesel engine set up.
  • Like I mentioned prior, while at anchor the Hybrid System can be used to power the entire house thus eliminating the generator exhaust: no longer will swimmers
    have to deal with the exhaust immersed in the water surrounding the yacht nor
    will those on deck smell the fumes. It is also more peaceful with less noise.
  • For emergency maintenance issues on the main engine the Hybrid System can be activated allowing one to work on the diesel engine without having immobilize
    the yacht.

These are but a few benefits that the Hybrid System will give the Naumachos line of
yachts thus saving the owner in maintenance & fuel costs, and enhancing the journey
through minimizing the impact on the environment.

Cantiere Navale di Pesaro is an up and coming shipyard at the forefront of the ‘Green’
yachting movement. Their approach is a refreshing change to the ways of the past. As the yard expands its facility this environmentally sensitive stand is even evident in their new build shed that will be retrofitted with a roof lined with solar panels that will be used to harness additional power for the yard.

The information above is but one example of the vision that CNP takes as looks into the

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About the Author

Alex worked his way up from deck hand to captain. He currently works as a yacht broker for Bartram & Brakenhoff a boutique brokerage house in Ft. Lauderdale. Send him an email for additional information

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