Propeller walk

A propeller is called right-handed if it rotates clockwise in forward gear (when viewed from the stern).

In reverse gear, the turning effect will be much stronger and with opposite direction (pushing the aft to port).

If the rotating water cone contacts the ship's hull, a sideways force is generated.

When in reverse gear, the water will hit the hull directly, resulting in propeller walk.

I. W.: “Hydrodynamic Aspects of Shallow Water Collisions” Transactions of the Royal Institution of Naval Architects, Volume 118, 1976.

Propeller walk single propeller in reverse
Axial and radial movement of propeller water (Note, the prop on the left is right handed whilst the one on the right is left handed.)
Radial movement of propeller water (left-handed prop)