september 2010

SCHOTTEL Product Offensive: new Rudderpropellers, Twin Propellers, Controllable Pitch Propellers and Transverse Thrusters

New SCHOTTEL Rudderpropellers and Twin Propellers
Since its invention by SCHOTTEL’s founder Josef Becker 60 years ago, the Rudderpropeller has been a core product in SCHOTTEL’s product range. On the basis of comprehensive research and development activities, SCHOTTEL has constantly adapted the Rudderpropeller to the growing demands of the shipping sector. In this connection, the SCHOTTEL Twin Propeller (STP) was also launched onto the market in 1996.

Excellent manoeuvring due to 360° rotation
SRP and STP are based on the same principle: the thrusters can be rotated through 360° and thus not only deliver the required thrust but are also in particular demand when precise manoeuvring, e.g. in ports, and dynamic positioning, e.g. in the offshore sector, are called for.

There is a wide range of potential applications: fitted with a nozzle, the Rudderpropeller produces especially powerful thrust. This is required by small work vessels or ferries, for example, but also by craft with extremely high bollard pull, such as tugs.

More power with two propellers
The Twin Propeller is equipped with two propellers rotating in the same direction. The push propeller can therefore be made with the same diameter as the pull propeller. This increases the active propeller area and the efficiency while reducing the propeller load and thus the noise generation. The efficiency is further enhanced by the very slender underwater gearbox. The Twin Propeller has a range of application extending from the offshore sector to river vessels and also represents an ecological solution, as the higher efficiency decreases the fuel consumption. The reduced noise and vibration level of the STP make it especially suitable for use on river cruise ships. The relative arrangement of the front pull propeller and rear push propeller is such that the vortex of the front propeller passes between the blades of the rear propeller without the cavitation swirl generated by the blade tips of the pull propeller striking the blades of the push propeller. Contraction of the slip stream in the pull propeller means that more water reaches the push propeller from the sides. The underwater gearbox is hydrodynamically optimized and provided with lateral control fins. The swirl energy in the propeller stream generated by the pull propeller is thus partially recovered. The flow around the control fins creates a lift component, which has a thrust-increasing effect.

New Rudderpropellers and Twin Propellers for small vessels
The new SRP 0320 is the uprated successor to the SRP/STP 110 and is thus a fitting response to current market requirements. With its modular design, technical innovations and additional functions, this thruster fully measures up to the increased customer expectations.
Featuring a diameter of 0.65 - 0.85 m and a weight of 1.50 t, the Rudderpropeller provides a power of 150 - 220 kW at 1800/2300 r.p.m..

SRP and STP 0320: greater thrust, easier installation, simpler service
The SCHOTTEL engineers have focussed entirely on the requirements of the users of small thrusters in terms of operation, installation and service. For instance it is the first time that a Rudderpropeller of this size is also available with a nozzle and has furthermore been developed specially for shallow waters. That results in more thrust for propulsion and manoeuvring.
Installation has been facilitated by means of an integrated hydraulic system. This eliminates the need for any further installation work onboard the vessel (“Plug & Play”). Maintenance too has been simplified thanks to an easily exchangeable underwater gearbox and the freely accessible coupling.
The new system is intended primarily for use on small work vessels, barges, push boats, passenger ships and double-ended ferries.

New SCHOTTEL SRP and STP units for high-performance vessels
With the SRP 4000, SCHOTTEL is introducing the first Rudderpropeller of the entirely new future generation of azimuth thrusters at the time of the SMM exhibition. Through intensive research and development in the areas of structural mechanics and hydrodynamic design, SCHOTTEL has succeeded in developing a very compact Rudderpropeller with a weight reduction of some 20 percent in relation to the equivalent model from the current series. Besides the noise-optimized gearbox, which is designed for a large range of possible input speeds, and the compact construction, which allows an approximately 35 percent reduction of the oil charge, this new SRP generation is also characterized by integrated steering hydraulics. For high-speed applications, a propeller nozzle specially tailored to these requirements is available. The weight reduction and the decreased oil charge are directly reflected in attractive cost benefits for the customer.
The SRP 4000 T variant has been specially developed for tug applications to cover the power range of terminal tugs with a bollard pull of 80 t or more.

The new SRP 4000 generation is also available in the proven design as a SCHOTTEL Twin Propeller STP for vessels with relatively high speeds (offshore supply vessels, ferries). The propulsion system can be operated with a high efficiency and free of cavitation up to 18 kn.

New SCHOTTEL CP propellers for fast vessels
Controllable-pitch propeller systems have been in the product portfolio of the SCHOTTEL Group for more than 10 years. They are used wherever utmost requirements in terms of variable modes of application and high manoeuvrability have to be met, from conventional freighters to fast ferries and powerful tugs, and can even be implemented for continuous operation under extreme loads in demanding offshore service with dynamic positioning.

For applications requiring a lightweight construction at the same time as high power, e.g. military vessels or yachts, SCHOTTEL has extended its product range to include a five-blade variant. It is based on the proven design principles of the standard systems and offers a high power density and a weight reduced by up to 15% while retaining the accustomed reliability and robustness. The propellers have been optimized in accordance with the latest state of the art in hydrodynamics and structural mechanics and are characterized by improved efficiency, reduced pressure pulses and structurally optimized hubs. At the same time, the simple and maintenance-friendly design and functional principle of the classic SCHOTTEL CP propeller systems have been retained.

SCHOTTEL SCP controllable-pitch propeller systems of the 5-X series are available in sizes from SCP 046 5-XG to SCP 154 5-XG for power ratings from 1000 to 30,000 kW.
For all sizes there is an optional version with feathering capability. This makes it possible to satisfy the requirements of different operational states in the case of multi-shaft systems and combined propulsion concepts such as a CP propeller in combination with an SCD.

New SCHOTTEL Transverse Thrusters for the high power range
Transverse thrusters are installed in the bow or stern in order to improve the manoeuvrability of a vessel. Depending on the type of vessel, the range of application extends from brief docking and casting-off in ports with a limited number of operating hours every year up to continuous operation under extreme load conditions in demanding offshore applications with dynamic positioning.
For these applications, SCHOTTEL has introduced a completely re-engineered series of transverse thrusters with the new designation STT 1-5 in the power range from 600 kW to 1500 kW. As usual, they are available with either FP or CP propellers. The latest research and development findings have resulted in hydrodynamically optimized propeller designs with improved efficiencies and reduction of the noises and also the losses at no or low propeller pitch.
The tough DP requirements in offshore applications have been taken into particular account. The thrusters have been designed with reserves for these applications. The propeller blade tip speed and propeller load have been reduced to a minimum, which substantially increases the service life of the drive seals and bearings, and of the propeller hub and blades. SCHOTTEL STTs can be powered by diesel engines, electric motors or hydraulic motors. Electric motors are included optionally in the scope of supply.

The SCHOTTEL Group, with its headquarters in Spay/Rhine, is one of the world’s leading manufacturers of propulsion and steering systems for ships and offshore applications. Founded in 1921, the company has been developing and manufacturing for almost 60 years azimuth propulsion and manoeuvring systems, complete propulsion systems with power ratings of up to 30 MW, and steering systems for vessels of all sizes and types. Around 100 sales and service locations worldwide ensure customer proximity.