Electric Propulsion

Fischer Panda Electric Drive Systems for Boats with Power Outputs up to 150kW

The silent revolution.

There is hardly a more enchanting and natural experience than sailing a yacht quietly and peacefully with light wind in calm waters at moderate speed. This marvellous feeling has always been the envy of every motor boat owner. This has been brought about by a new concept. DE-Whisperprop is the new electrical drive system for boats. Instead of coupling the engine to the propeller shaft, a generator supplies power directly to an electric motor. The new Whisperprop drives are so quiet that they are practically inaudible at normal operating speeds. Assuming that the Panda generator has been correctly installed, one has to experience at first hand the extremely low, almost inaudible noise and vibration when compared to traditional propulsion techniques. Very little noise is transmitted externally. Even noise from the exhaust can be completely eliminated.

Advantages for the DE Whisperprop System

The 20 outstanding advantages of the DE Whisperprop Drive systems

The combination of the Fischer Panda diesel generator and a state of the art electric motor has many advantages:

Perfect sound insulation. If the generator is correctly installed, internal and external sounds are almost inaudible.
Total freedom from typical drive line vibration. The Panda generator and electric motor produce little vibration at normal cruising speed.
Extreme manoeuvrability through rotating drive units. The boat is now capable of very tight radius turns.
When travelling backwards (in reverse gear), it is possible to achieve almost the same exceptional manoeuvrability as when moving forwards. Transverse thrusters are no longer needed.

The speed of the main power unit (Panda diesel generator) and the electric propeller drive motors are regulated independently from each other. Benefits:

Optimal silent operation of the entire drive system
Most efficient use of the electrical output
Fuel savings up to 25% to 40%

It is possible with some yacht designs to reach hull speeds approx. 0,5kW per 1 ton displacement when travelling on calm water. The electric drive motor speed can then be set efficiently to the prop shaft for the requested hull speed.

With sea swell and wind working against the bow of the boat, the generator can work at maximum performance within its optimal speed range and the ships speed (via the propeller revolutions) can be independently reduced from the motor speed when appropriate.

A reduction in speed is normally only possible with a conventional drive by a reduction of the engine revolutions. However this will also result in a limitation on the available performance. The DE System retains the full performance because the propeller revolutions are independent from the engine revolutions.

One generator can supply several propeller drive units.
Combined use. The generator sets are also used for the on board power supply.
Several generators can work in parallel. This allows the allocation of load to be spread over two smaller sets. Effective use of this method can only be optimized when only a portion of the total electrical output is requested. All the gensets will operate only when the total performance is required.
The parallel system remains operational during repairs because each generator can supply all of the electric motors. This causes the highest possible operational security.
An essential weight saving can be reached by the combined utilization of the generators for both onboard power supply and power for prop shaft drive motor.
The Panda PM electric motors and the Panda AGT generators are so efficient that the system efficiency of a complete DE drive system can exceed that of a conventional mechanical drive system.
Since an electric motor in the low speed area delivers higher torque than a combustion engine within the same RPM range, a significantly higher thrust is achieved at the propeller.
With the application of a DE Drive, essentially a smaller machine than a conventional drive is required.

On the basis of these arguments, the weight of the complete drive-installation can be even reduced by more than 50%. This saving results from the following factors:

A Panda generator with 30% the performance of a conventional diesel engine weighs approx. 33% less.
With the weight reduction, the ship is able to achieve a better travelling characteristic. As a result the required drive performance can be reduced.
As opposed to installing one heavy slow running machine, multiple parallel operating units could be installed to supply the correct amount of power upon demand.

Many interesting different drive solutions are possible because the electric motors are so compactly built:

Aziprop drives. The drive motor is located underneath the hull in a waterproof rotatable assembly (fully sealed stainless steel housing) and can be rotated up to 90° port and starboard. This option allows incredible directional maneuverability that until now had never been thought possible.
Retractable special drives with directly integrated electric motors that can fully rotate 360°. This is particularly useful for sailboats and greatly reduces hull drag.
With this the drive has a double function. Firstly as primary drive and secondly as a freely rotatable bow or stern thruster.
Hübner Braun drive (thrust in every desired direction within an adjustable range of 360°)
DE Saildrive 180° rotable with rotary wing propeller.
Installation of an electric motor within the shaft system.
Attachment of a rotatable motor to the stern in the same way as an outboard motor.
Multiple drive motors can be driven from a central generator. This option gives the ship an outstanding maneuverability.

Since the generator is not connected over a fixed shaft with the propeller, the freedom of choice for the location for the generator can vary. This brings new possibilities with regard to the generator location, for example, foredeck area, stern or at one side etc,
The operation of a conventional bow thruster, especially one with a relatively high performance (from approx 6 kW to 100 kW) is substantially simpler and more efficient than previously possible because a Panda PM Motor can be used. This can also be driven by the generator.
The operation of an additional high performance units e.g. air-compressors is also substantially easier and more efficient than before, for these a Panda PM permanent magnet motor can also be installed into these systems.

Electric Propulsion

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