Navigation is the technique of planning a course from one place to another. Historically, safety, timeliness and cost factors (fuel consumption, etc) into course planning. All travel requires navigation in some form or fashion. If you drive across town, you are navigating even if you are only planning the course in your head.Dead Reckoning
Dead reckoning is the determination of position by advancing a previously determined position by distances and directions travelled. In essence, if you know where you were, the direction you are going and the distance you have travelled, you should be able to figure out where you are now.Errors can build in dead reckoning solutions. First, a position solution can be only as good as the quality of the previous position solution. If you were not able to measure where you were very well, you can't have any more confidence in your current solution no matter how well you measured your speed or direction of travel. Second, a position solution can be only as your ability to measure speed and direction of travel.
The accuracy of navigation measurements can be distorted by environmental factors such as water and air currents.
Course and Course Made Good
Course is the direction of travel, while Course Made Good is the direction actually travelled. This sounds confusing, but isn't really. Let's take an example. Say a boat is travelling eastward across a river (across the current). The ship's course is toward the east. The river is running to the south, pushing the boat southward. While the boat's course is to the east, the course made good is actually to the southeast.Speed and Speed Made Good
Speed is the velocity through the environment while Speed Made Good is the actual velocity with respect to the path being travelled. An aircraft's instruments may measure a speed of 600 knots. A 100 knot headwind will reduce the aircraft's speed made good over the ground to 500 knots.
GPS provides the user with fairly accurate absolute position and time virtually anywhere in the world.Navigating by dead reckoning, the navigator determines the desired position, determines the current position, then calculates a bearing to travel to reach the intended position.