SCHOTTEL RudderPropeller: The Leading Invention since 1950

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With the invention of the SCHOTTEL RudderPropeller (SRP) in 1950, ships could – for the first time – use the full power of their propulsion system for manoeuvering. This Z-drive eliminated the need for a separate rudder blade and featured a propeller that could be steered endlessly through 360 degrees. This technical breakthrough had a profound impact on shipbuilding and marine operations.

17,000+ units installed
"Throughout its 75-year history, the SRP has played a pivotal role in pioneering new maritime markets. From early harbour tugboats to offshore energy exploration, to today’s leading solution for fully electric tugs – this versatile propulsion system has consistently been the preferred choice in response to emerging demands,” says SCHOTTEL CEO Stefan Kaul, reflecting on the SRP’s remarkable success. Customers value SCHOTTEL’s extensive technical expertise and tailored after-sales service. “Behind the more than 17,000 SRPs sold are partnerships built on trust and reliability. That is deeply moving and a source of pride.”

Used in 120+ vessel types
Today, the SRP is available in numerous variants, covering a wide range of power sources, installation options, and operational requirements. Its exceptional versatility is evident from the fact that it is used in more than 120 different vessel types for a variety of applications.
 

75 Years of SRP: Historical Milestones

Late 1940s: SCHOTTEL founder Josef Becker, who is extremely interested in technical and shipbuilding matters, is looking for a new combination of propulsion and steering. He does not have an engineering degree, but instead relies on his apprenticeship as a metalworker and his experience working at a shipyard in Koblenz, Germany. The first model tests take place in his bathtub at home.

1950: The first rudder propeller (150 hp/110 kW) is installed in the company's own boat, the Magdalena, named after Josef Becker's wife.

1952: Ships equipped with SRPs belonging to the Rhineland-Palatinate water police are deployed during a flood disaster in the Netherlands. Their exceptional manoeuvrability causes a sensation and leads to several orders from the local water police. The following year, the first major order for 15 ships for the French Rhine Army arrives–marking an international breakthrough.

1955: On November 23, the former SCHOTTEL shipyard is granted Patent No. 1025293 for the ‘steerable propeller drive for ships with outboard motors.’

1963: Offshore oil drilling requires ships that can be positioned precisely. The French core drilling vessel Trebel is equipped with the world’s first dynamic positioning system. Two SRP 150 units ensure precise positioning and maximum manoeuvrability. Numerous further developments of the SRP follow for almost all types of vessels used in oil and gas exploration.

1967: SCHOTTEL collaborates with a shipping company in Hamburg, Germany, to develop the first harbour tug with rudder propellers. Its high market acceptance is reflected in strong sales figures.

1980s: The SRP ideally meets the demands of the newly designed ASD (Azimuth Stern Drive) tug. Sales rise significantly, boosted by SCHOTTEL’s growing international presence.

1986: Underwater-mountable SRP 4500 units are installed in the world’s largest offshore crane vessel, the Micoperi 7000 – the most powerful rudder propellers at that time.

1998/1999: The growing size of container ships requires more powerful harbour tugs. The newly developed SRP 1515 is an immediate success. By 2025, around 1,300 units of this model – later renamed SRP 460/SRP 490 – will have been delivered, making it the world’s most successful azimuth propulsion system.

2005: With over 600 equipped tugs, SCHOTTEL becomes the market leader in this vessel category.

2016: Following extensive research and development in collaboration with the Technical University of Dresden in Germany, the HTG high-performance gearbox is introduced. Among other improvements, it enables drive torque to be increased by up to 15 percent with the same bevel gear dimensions.

2017: The anodes required for corrosion protection are repositioned in the rear cross-section of the nozzle. The “ProAnode” improves hydrodynamic flow characteristics and offers economic benefits. At the same time, it gives the SRP a distinctive appearance.

2019: SYDRIVE, a mechanical and electrical hybrid drive solution for the SRP, is launched – offering numerous operational and environmental advantages. In 2025, four SRP 710 units with SYDRIVE-M and up to 120 tons of bollard pull mark SCHOTTEL’s most powerful hybrid drive.

2023: The fast-responsive SRP-D is launched and sells over 50 units by the anniversary year. It is an indispensable system for ships used in the commissioning and maintenance of wind farms. Thanks to improved positioning accuracy, vessels equipped with the SRP-D can operate more efficiently and safely, remaining in service longer throughout the year.

2025: According to current market studies, SCHOTTEL RudderPropellers power more than half of the world’s fully electric tugs and also hold a leading position in the hybrid tug market.

More information on 75 years of SCHOTTEL RudderPropeller: srp.schottel.com.

SRP: the starting point for SCHOTTEL’s broad propulsion portfolio
The design principles of the SRP have had a significant influence on azimuth technology in the global maritime market. At SCHOTTEL, it has paved the way for the development of additional main and auxiliary propulsion systems, each of which is tailored to the diverse operational profiles of modern vessels. Alongside the SRP, customers choose other main drives, such as the controllable pitch propeller (SCP) or the azimuth pull propeller (SCHOTTEL EcoPeller), as well as a wide range of auxiliary drives.