This technique is known as Dead reckoning. Using all this information, the navigator calculates the distance and route which he has covered and keeps track of his movement by plotting a nautical chart ( also called a sea chart). The direction of movement (by using a compass) When he starts to move (in the mid-sea or mid sky), he can get some known (measured) factors other than the position/location in terms of a fixed landmark. When it is the beginning, the navigator is clearly aware of the position/location.