S-two GmbH & Co. KG

Lage, Germany

HOERBIGER Power Units ensure Safety at Sea

[ Published in HOERBIGER@MOTION 03/2010 ]

More than 15,000 ocean-going freighters supply the world with raw materials and finished goods. Two aspects are key for the operators of jumbo container ships, tankers, and bulk freighters: maximum efficiency and safety. S-two GmbH & Co. KG headquartered in Lage, Germany, builds ship control systems for regulating ballast fluids in the hull which stabilize huge ships even in rough seas. For its systems, S-two relies on remote actuator technology using key components from HOERBIGER Automatisierungstechnik GmbH.

Huge container ships are icons of globalization. Over 90 percent of international trade is transported by sea. In order to maintain jumbo container ships as well as feeder vessels, which are smaller ships carrying loads of up to 1,000 containers, in a stationary position during loading and unloading and allow them to defy rough seas, special systems are required to stabilize the ships.

Poseidon EH is the innovative ship control system developed by S-two which was first unveiled in 2006. The system focuses on managing the fluids in the hull, which contains numerous tanks holding fuel such as heavy fuel and diesel, ballast water, drinking water, and bilge water.

Poseidon EH also ensures that the draft of the ship is optimized. The draft is crucial for the economical operation of a freighter and must be maintained regardless of the payload. In order to equalize the ballast, the fluid volumes in the hull of the vessel are pumped back and forth between individual tanks – arranged in groups and according to media – by precisely coordinated opening and closing processes of the valves.

The valve opening and closing processes traditionally employ oil hydraulics. Each individual valve is actuated from a central control console via a dedicated hydraulic line. Previously, hundreds of yards of hydraulic lines had to be installed for this purpose. Poseidon EH dispenses with the maze of hydraulic lines.

Instead, the ship control system relies on local electrohydraulic power units from HOERBIGER Automatisierungstechnik GmbH in Altenstadt, Germany. Small electrohydraulic power units from HOERBIGER are used to actuate the valves. They are screwed directly to each individual valve, including all electric and hydraulic components. As a result, the miles of maintenance-intensive hydraulic installations can be eliminated. The power units are controlled electrically, while the actuation of the valves, which requires high forces, is done hydraulically. The pump of the HOERBIGER power unit generates the necessary pressure. The actuator also accommodates the necessary supply and compensating reservoir for the hydraulic oil. As a result, the expensive central hydraulic system can be eliminated, along with the complex maze of miles of stainless steel lines.


The compact hydraulic power units for marine valves developed by HOERBIGER Automatisierungstechnik GmbH in Altenstadt, Germany, can be flange-mounted directly to the actuator of the valve. The motor is encased, achieving classification in accordance with protection class IP 68. The core of the hydraulic power unit is a radial piston pump, which is directly integrated into the housing and thus constitutes an extremely compact design.

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During the economic crisis, freighter shipbuilding suffered considerable losses. The transport of goods has significantly decreased. Maritime freight was hit especially hard since 90 percent of all international transports are made by sea. Nonetheless, the prospects for the future of logistics are excellent. The trend toward globalization is unwaning and will require high freight capacities in the future. As a result of the economic crisis, the shipyard landscape has changed at a breathtaking pace. Freighter shipbuilding in Europe is almost non-existent. Even Turkey, previously one of the key players in the world market, is clearly scaling back. The winners are the shipyards in China. Under these circumstances and considering the trend toward the construction of increasingly larger freighters, innovations that help to save space, time, and money—key influencing factors in shipbuilding—are in demand.


S-two GmbH & Co. KG in Lage, Germany, founded in 2004, is a worldwide specialist provider of ship control systems. Since the company's inception, highly integrated control systems for the shipbuilding industry have formed the core business. The company has maintained a close partnership with HOERBIGER Automatisierungstechnik GmbH in Altenstadt, Germany, since 2006.