Every boater has heard that to clear a starboard (right) side berth one should back off slowly at first. But why? The answer is side force.
Side force is caused by the turning of the propeller. At low speed side force moves the stern of the boat to the side, almost as though the prop were crawling along the bottom.
On a single screw vessel (single engine/prop) side force moves the stern to starboard in forward and to the port (left) in reverse. So, when docked on the starboard with a single screw, clear by starting in reverse. The stern will move away from the dock as the boat backs down. Forward may be used when the boat is sufficiently clear.
But, when shifting into forward remember that the boat’s pivot point is back from the bow about one third of the boat’s length. The stern of the boat will move to the starboard (right) while the bow moves to port (left). If you are not careful this could send the stern into the dock.
Backing out of a port side berth is different. Keep a forward line attached to the dock. Apply full left rudder and go forward slowly till the stern is clear of the dock. Take in the line, center the rudder, and back away. When fully clear go forward.