Differences Between Dead Reckoning and Celestial Navigation?

Basic Principles of Dead Reckoning

Dead reckoning is a method of estimating a current position by tracking previous movement. It is based on the principle of “knowing where you’ve been to know where you are.” This method relies on accurate speed, direction, and elapsed time, as well as a mental map of previous routes. By plotting previous positions and course changes on a chart or map, a navigator can estimate their current position.

Calculating Position Using Dead Reckoning

To calculate position using dead reckoning, a navigator must know their speed, direction, and elapsed time. The navigator can then use a chart or map to plot their previous position and course changes. The formula for calculating position is: new position = previous position + (speed x time x direction). For example, if a navigator travels at 5 knots for 8 hours in a northeasterly direction from a known position, their new position can be calculated.

Celestial Navigation Techniques

Celestial navigation involves using celestial bodies, such as the sun, moon, or stars, to determine position. A sextant is used to measure the angle between a celestial body and the horizon. This angle, combined with a table of celestial body positions, can be used to determine the navigator’s latitude. To determine longitude, a navigator must also know the time difference between their location and a reference location, as well as the celestial body’s position. For example, using the sun’s position at noon and a reference latitude, a navigator can determine their latitude. By knowing the time difference between locations and celestial body positions, a navigator can also estimate their longitude.