Voith Water Trecker BIENE VSP65BM

 The BIENE (Bee) was the first Voith tractor to be built and tested. For the first time, the drive was installed from the rear to the front.

1) Extensive model tests have shown that the negative pressure field of the propeller attenuates the height of the bow wave, so that the vehicle does not raise any shore-fixing waves even when travelling in a canal. In detail, the model test showed that at 4 knots the suction figure is zero, i.e. the negative pressure field pulling forward cancels out the damaging frictional suction. From 4 knots upwards, there is even an increase in thrust, i.e. the negative pressure forces reduce the pressure increase at the bow to such an extent that not only is the frictional suction cancelled out, but a positive thrust gain even remains. Compared to the stern arrangement, where normally 15-20% thrust reduction due to suction occurs, the bow drive even achieves a gain of at least 20% during normal towing. The end plate (protective plate under the VSP) also provides a further thrust gain of 6%, which compensates for the drag of the props during free flight.
After these model tests, it was decided to build the first large-scale version. BIENE

It had a propulsion power of 115hp, the wing diameter was 1.4m, the wing length was 65cm.

The test runs carried out in August 1952 showed the following result:
Time for 180° turn                10 sec.
Free speed                           14 km/h
Hawser pull on the pile         1720 kg
Braking time from full speed
Forward or reverse speed     3.5 sec.
Reverse speed                      13.8km/h

With the same towing power, the draught and the size of the tug could be reduced. The manoeuvrability was extremely increased with this concept.
In addition to the chosen shape, the bow drive is also important for the good seaworthiness. It makes it possible to always keep the vehicle safely in front of the sea without ever running the risk of being pushed sideways.
This made it an ideal new type of tug for harbours.
The Biene was built in 1952 in Oberwinter near Bonn and underwent extensive tests, both on the Rhine, the adjacent canals but also in the ports of Bremen and Hamburg.

This was the starting signal for many Voith water tractors until today.

This was followed in 1953 by the Hornisse, type Lütje Horn (Deutsches Marinemuseum) and in 1954 by the well-known tugboat Stier, which is now in the Bremerhaven Maritime Museum.

Dimensions:
Length o.a.:     508mm
Width o.a.:       148mm
Draught:           100mm
Weight:             1720g max.
Rotor speed    429min-1
Direction of rotation counterclockwise, seen from above

Scale approx. : 1:20

In agreement with Voith the draught of the model was increased by 5mm and thus adapted to the VSP.
 The original model was tested at Voith in the test tank.
You can see the video here BIENE im Voith Testtank or here BIENE Voith-Werksvideo

Kit contents:

- GRP hull
- VSP65BM with regulator
- 2 mini digital servos 5-8,4V
- Laser plates, ABS and plywood
- Material for the discs
- 3D printed parts such as pressure plate with recess for lead weight.
- Lamps, bollards, cleats, wires, aluminium drop profile, small parts
- Towing gear, lead ballast
- Flag, specially made for the BIENE
- Flag DE

1) with kind permission of Voith, excerpt from an offprint of "Hansa". 
Author Dipl.-Ing Wolfgang Baer, Heidenheim No 1/2 1953, pages 114-117
The original text is in German and has been translated by us.

The final kit equipment may differ from the pictures of the prototype.