The Evolution of Navigation: Pre-GPS Techniques in Ship Travel

Before the advent of Global Positioning Systems (GPS), navigating the vast oceans relied heavily on advanced mathematics, celestial observations, and other innovative techniques. This article explores the methods used by early pilots and sailors to determine their positions and course on the high seas.

Latitude Calculation: Shooting the Sun

One of the fundamental aspects of navigation prior to GPS was the determination of latitude. At noon, a(n) officer would engage in a process known as "shooting the sun." By carefully calculating the day of the year and the angle of the sun above the horizon, one could accurately determine the ship's latitude.

Longitude was a more challenging task, requiring the use of an accurate clock. The earth rotates about its axis, a full rotation taking 24 hours. For a standard equator, each hour represents approximately 1000 miles. At 45 degrees latitude, this distance is halved, and closer to the poles, the distance per hour gradually decreases. Therefore, while latitude calculation was relatively simple, determining longitude was a complex task.

Dead Reckoning: The Art of Estimation

Dead reckoning, a method of navigation, involves estimating the ship's position based on the initial position, course traveled, and speed. The process included recording the course and speed at regular intervals, often every hour. sailors would throw a piece of wood overboard and count the number of knots that passed a hand or the stern of the ship in a set period. This captured the ship's speed and distance traveled.

A record of the ship's journey, known as the log, was maintained. The speed was measured in knots, a term derived from this method of estimation. Regularly, the officers would cross-check their position by observing the sun's movement and using a compass to maintain direction.

Approaching Land: Imagined and Real Landmarks

As the ship approached land, a lookout would be posted in the crow’s nest, a platform near the top of the tallest mast, or later, a special observation mast with a telescope or binoculars. This vantage point allowed the lookout to see farther over the curvature of the Earth. However, the ship itself could be hard to spot, especially at night, as land often appeared as a single vertical line, making it more challenging to distinguish from a ship.

Signals from the land, such as cooking fires, could serve as useful landmarks, especially at night. These were easier to identify than the ship itself. Once close enough, the bowsprit man was stationed to perform a practice known as leading with a lead weight. This tool was a simple method to determine the depth of the water and the type of seabed. By coating the weight with lard, sailors could retrieve a sample to determine the nature of the seabed, which would indicate whether it was safe for the ship to pass over.

Training and Discipline on Board

Midshipmen played a crucial role in training and serving as apprentice officers, often starting at age 12. By the time an officer was 18 or 19, they might be leading a crew of men, mostly older than themselves. Formal training in navigation was not common, and even swimming was unusual, as it was forbidden to prevent mutinies or desertion.

The living conditions on board were primitive, and the term "heads" for toilets derived from the practice of sailors relieving themselves by climbing into ropes and nets at the ship's head or bow. This method was effective in removing excess waste. Officers might have larger crocks for their waste, but conditions remained extremely primitive.

Conclusion

While many of the techniques described may seem rudimentary by today's standards, the ingenuity of early navigators and sailors allowed them to traverse vast oceans with a remarkable degree of accuracy. The development of GPS has made navigation easier and more precise, but the historical methods highlighted in this article represent a testament to human ingenuity and adaptability.