An experienced boat operator knows how to stop her vessel and hold it in place, or to gently move sideways. That sideways movement is often called "walking." Experienced boat operators usually have trouble describing exactly what they do with the wheel, throttle and shifter to move a boat sideways, but they all agree that mastering the technique takes a lot of practice before it becomes second nature. Here's how it is done.
Stand at the helm holding the shift levers. Straighten the steering wheel to set the rudder amidships. Allow the boat to settle into a full stop, with the throttle in neutral so that only wind and current are affecting the position of the boat.
Push the port shifter forward and the starboard shifter to reverse. Leave the throttle at idle. The vessel will begin to gradually rotate clockwise, as though your hands were turning the boat.
Repeat the same procedure in both directions, using only the shifters to manoeuvre, turning the boat in its own length.
Stop the boat, turn the wheel hard left and imagine the port rudder, located aft of the port propeller, swinging left. Shift the port engine into forward. The propeller forces a current of water to wash over the rudder. This pushes the stern of the boat to starboard and begins to ease the boat forward. Counteract the forward motion by putting the starboard shifter in reverse. Notice that the boat stops turning, and begins easing sideways, or "walking" to starboard.
Shift into neutral, turn the wheel hard right, shift the starboard engine into forward and the port engine to reverse. You boat will be "walking" to port. The rest is practice...lots of practice.
Leave the throttles in idle while practicing these skills.
To avoid collision, practice in open water away from docks and other vessels.