Effects of the Propeller on the Rudder Copy

The “typical” manoeuvre, described in the previous chapter, initially takes advantage of the effects due to the propeller’s slipstream, which, in forward motion, violently hits the rudder blade, which, hard over to a side, quickly turns the ship. We had seen that the slipstream, acting on the rudder with the vessel, stopped, and the propeller in forwarding moving, making the vessel turn even before it gathered headway.


With the engine in reverse, however, the wake aspirated by the propeller increases the swirling movements around the rudder, reducing its effect.

Generally, the rudder’s position is indifferent in reverse and the ship with little sternway. The rudder begins to make its presence appreciated only with increasing speed.

When influenced by external causes such as interactions with the seafloor, wind, current, ship’s attitude, etc., these effects can sometimes be opposite to those described. It is a good pilot practice to try, where possible, the paddle-wheel effect when handling a vessel for the first time or, in any case, ask the Master for details during the initial exchange of information once on the bridge. It is essential to carefully evaluate the environment where we handle our ship, identify critical points, and anticipate any unwanted effects.