Seitenruder

Seitenruder is a term describing a rudder mounted on the side of a vessel’s hull, used to assist or substitute a stern-mounted rudder. It functions as an auxiliary steering surface that can improve maneuverability in conditions where a conventional stern rudder is less effective, such as at very low speeds, in confined waters, or for hull forms with unfavorable flow to a rear-facing rudder.

Typically, a Seitenruder is placed near the midship or bow on one side of the hull, though some designs include multiple side rudders on different locations. It is driven by the ship’s steering system, with actuation through a tiller, wheel, or hydraulic/electric mechanisms, and may be retractable or fixed depending on the design. The rudder deflects water to create a yawing moment, and its use is generally coordinated with the main rudder and propeller direction to achieve the desired turn.

Applications of side rudders vary across vessel types. They have appeared in historical riverboats and coastal craft, and in some contemporary or experimental designs to augment steering or provide redundancy. The choice of side and integration with other steering controls depend on hull geometry, propulsion, and docking requirements.

Advantages of a Seitenruder include improved low-speed handling and greater maneuverability in tight spaces, along with potential redundancy in steering. Disadvantages can be increased hull complexity, additional drag, maintenance needs, and the possibility of interference with propulsion or docking operations in certain configurations. See also rudder and dual-rudder arrangements for related concepts.