What does the helm command shift the rudder mean?

The helm command "shift the rudder" instructs the helmsman (the person with their hand on the wheel) to give the same angle in the opposite direction. Example: If the ship's rudder is at Left 10 degrees, it will be switched to Right 10 degrees....if it is at Right 25 degrees, the helm should pring it to Left 25. A Williamson turn is a typical situation which this command will be useful. Hope this helps... I am a Maine Maritime Grad with a Second Mate Unlimited and 1600 Ton Master's license, just to provide some assurance that my answer is correct.