Propeller Walk

The lateral movement of a boat’s stern caused by the rotational forces of the propeller, typically noticeable when operating at low speeds or in reverse.

Propeller walk, also known as “prop walk,” is a phenomenon that occurs due to the asymmetrical thrust generated by a propeller as it rotates in the water. This effect is most pronounced in single-screw vessels and is influenced by the direction of propeller rotation, the hull shape, and the rudder configuration. When a propeller spins, the blades on one side of the propeller disc have a slightly different angle of attack and water pressure compared to the opposite side. This imbalance creates a sideways force that causes the stern of the vessel to “walk” to one side. For example, a right-handed propeller (one that turns clockwise when viewed from astern) will typically cause the stern to walk to port when reversing.

Propeller walk is most noticeable at low speeds, particularly when manoeuvring in tight spaces such as marinas or harbours. It can be both a challenge and a useful tool for skilled helmsmen. For instance, understanding and anticipating the direction of propeller walk can aid in docking or turning the vessel in confined areas. However, it can also complicate manoeuvres if the helmsman is unprepared for its effects. Twin-screw vessels experience less pronounced propeller walk because the opposing rotation of the two propellers tends to cancel out the lateral forces. Awareness of propeller walk is essential for safe and precise boat handling, especially for novice mariners learning to control single-screw vessels.