Game Development Reference
A special kind of thrust vectoring is called throttle steering . Imagine that a boat has two
engines. If one is run in forward and the other in reverse, the vessel will turn quite
rapidly. For a twin-engine vessel operating in close quarters, the rudders are often cen‐
tered and the vessel maneuvered solely by altering the throttle settings of the two props.
Another interesting maneuvering phenomenon that is closely related to thrust vectoring
is called propeller walk , or prop walk . This is especially important for vessels with only
one propeller moving in tight spaces. The cause of propeller walk is related to the fact
that most propellers are installed at an angle to the horizon. This angle causes the thrust
to be greater when the blades are moving down than when the blades are moving up‐
ward. In a propeller that turns clockwise, this creates a push to the right.
In forward gear the rudder is very effective at countering the propeller walk, but in
reverse the rudder is much less effective, making the propeller walk much more no‐
ticeable. This can add a significant amount of realism when you are simulating vessels
in docking maneuvers.