Backing and filling was originally a sailing term where the head sails were backed and filled with wind to bring a sailing ship down a narrow river. See
http://home.att.net/~ShipmodelFAQ/Re...-RN-BandF.html Now it is used to describe the art of using paddle
wheel effect (prop walk) to advantage to turn a single screw ship in the shortest distance possible. Basically the idea is to keep active water going over the rudder by having slow headway on but backing the screw and turning the ship in the opposite direction the screw walks the stern. As soon as the headway falls off so the rudder is ineffective, an ahead maneuver is ordered to get active water across the rudder again. Sometimes, as the ship stops the opposite helm is ordered with the engine running astern. It all works well until you add wind, tide, rocks and docks.
Gaz