What technique did seafarers use to look at the stars for navigation?

Safely and easily getting from one point to another while at sea is known as the art of navigation. Long ago, during the 4th century B.C., people didn't have access to the technology that we know today. They had to rely on other methods to get from A to B while at sea. One of these methods was to stay close to the shore and follow the shoreline. Seafarers would detect prominent landmarks to determine their progress at sea. If a seafarer did sail out of the sight of land, the North Star and the sun would be used to determine the northern and southern directions during the night and day. Some seafarers would use major constellations or even the directions that the birds flew and the fish swam to find their way at sea. Others would determine the vessel's progress at sea by measuring time with an hourglass. They would then multiply the time by the vessel's speed, which was determined by counting the pieces of seaweed that were passed. Needless to say, these methods weren't very accurate.

During the Middle Ages, which spanned from the 5th to the 15th century, sea transportation flourished, partly because of the introduction of the compass. Although the Chinese knew about the importance of magnetic fields and invented the compass, it was the Europeans who initially used it for sea navigation. It took a while before seafarers regularly started using the compass because many though it was inconsistent and some thought that it was operated by black magic. Another navigational source was the so-called Portolan Charts. Mapmakers made these expensive charts during the 13th century, using compiled sail data that was recorded by seamen. The charts were still not reliable because they lacked latitude, longitude, and distance information. Other tools that were used for navigation during this time were the astrolabe and the cross-staff. Both of these tools were used to measure the ship's position using the sun or a star.

Sea voyages were prominent during the 1400s, when the Age of Exploration started. Traders were desperately trying to get spices from Asia. They used these spices to keep food from spoiling. However, attempting to get to Asia by land wasn't easy because often, routes were closed due to wars. Instead, traders decided to find their way to Asia by sea. Explorers from Portugal were sent out to find sea routes, but the progress was slow because they feared hot water and sea monsters that they believed were present at the equator. The Portuguese explorers used so-called caravel ships. The lateen sails of these ships were able to sail toward the wind and provided speed. In 1492, Christopher Columbus used this type of vessel for his first voyage. According to Columbus' logs, he mainly used dead reckoning navigation. Dead reckoning was a method in which the navigator would measure the distance and course from a specific point, such as the port. He would mark the day's ending point on a chart, and this point would serve as the starting point for the next day. Dead reckoning didn't determine the ship's latitude. To do this, Columbus used celestial navigation, which is basically using the moon, sun, and stars to determine your position. Other tools that were used by Columbus for navigational purposes were the compass, hourglass, astrolabe, and quadrant. The latter was a tool that measured latitude by determining the angle between the sun or a star and the horizon.

Navigating during sea voyages nowadays is a lot easier than back then. After World War II, the development of electronic navigation aids progressed quickly. Today, captains have access to electronic calculators and computers to perform necessary calculations, and they also use a satellite navigation system or global positioning system to determine their location at sea. With access to these advanced technological developments, you can imagine that it's much harder for a ship to get lost at sea.

We don’t doubt that you’re an expert modern-day navigator, but do you know your cross staff from your astrolabe? We’re about to test your knowledge on nautical navigation throughout the ages!

How did we navigate before ECDIS?

Over the last five hundred years, dramatic advances in navigational science and technology have altered the navigator’s work and methods. Most recently and most significantly following the introduction of Electronic Chart Display and Information Systems (ECDIS). That said, the navigator’s basic task remains constant: to monitor where the ship has been and where it is now, and to plan where it will go next on its voyage.

Since ancient times it’s been possible to make an estimated calculation of latitude. For hundreds of years however, there were two very serious problems. In earlier years, this was limited understanding of direction – even following the birth of the magnetic compass, navigators had a very poor idea of direction or accuracy, since the concept of variation was not understood till many years later.

The second problem was even more important. In the absence of an accurate time keeping device such as a chronometer, a calculation of longitude was just not possible. It’s not then surprising that early navigation was problematic and often resulted in the navigator becoming lost, especially when out of sight of land.

The first ever clock leads to navigation of the pacific

Without doubt, the most famous pioneer of the navigation revolution was Captain James Cook who navigated the expanse of the Pacific thanks to the technical genius of John Harrison. In 1759, Harrison devised the first ever clock to keep the time exactly – in any variation of climate.

Keeping exact Greenwich Mean Time, Harrison’s clock enabled sailors to determine how many hours there were before or after that time and it was then possible to determine their longitude (degrees East to West position) on the globe.

So, that’s the obvious answer out of the way! What other navigational tools were first used to explore the earth? Let’s find out…

Lead line

Perhaps the oldest navigational tool on record originating in Egypt, the lead line is a measuring tool designed to assess the depth of the water and take a sample of the ocean floor. The lead line comprised of a hollow weight made of lead. In the middle of the weight sat a ball of animal fat which collected material from the ocean floor. This is the first recorded method of using depth and seabed material to determine location.

Compass

We’re pretty sure you got this one, but do you know the origins of the compass? Originating in the Han dynasty China between 300 and 200 BC, the compass uses the magnetic poles of the earth to find magnetic north. In later years, compasses used iron needles, which were magnetised by striking them with a lodestone. By 1300 in Medieval Europe and the Islamic world, dry compasses started to emerge, replaced by liquid-filled magnetic compasses in the 20th century.

Compass rose

Still used today, a compass rose is a design on a compass, map, nautical chart, or monument used to display the orientation of North, East, South, and West, as well as their intermediate points. Before compass roses were used on maps, lines were drawn from central points. These lines were hard to follow since there were so many lines intersecting each other on one map. The rose design was typically drawn in a way that made it easier to follow the directional lines.

Log line

The log line is an old instrument for measuring the speed of the ship. It consisted of a flat piece of wood which was weighted at the bottom edge to enable it to float upright in the water. The log was attached a long rope. The log line was wound on a spool so that it could be reeled out after the log was thrown into the water at the aft of the ship. The friction of the water held the log in place as the ship sailed away from it. As the ship sailed away from the log, the sailors taking the reading would count the number of knots that passed over the rail in a period of half-a-minute.

Sand glass

With records dating back to the 14th century and with likely use before in ancient times, the sand glass is a primitive timepiece used to measure the time (usually 30 seconds at a time) on a voyage, or on a specific navigational course. Sandglasses came with some major drawbacks, most notably that design and environmental factors affected the rate of the sand’s flow, giving inaccurate measurements. By the 19th century, they were replaced by more reliable & accurate mechanical timepieces and technology.

Cross staff

The cross staff, also known as the early sextant, consists of a wooden rod with a sliding crosspiece used for measuring the altitude of a star. It is thought to have originated in the 14th Century and was originally used as a land surveying instrument.

Nocturnal

Using the position of the stars to tell the time, the nocturnal was particularly primitive in design. One ring was set to the date, Polaris was sighted through the hole in the centre and the arm was moved into a position to align with pointer stars. Where the arm crossed the marked ring, the time was read.

Quadrant

An early instrument for measuring altitude of celestial bodies, consisting of a 90° graduated arc with a movable radius for measuring angles.

Astrolabe

The astrolabe was an inclinometer used to determine the latitude of a ship at sea by measuring the sun’s noon altitude (declination) or the meridian altitude of a star of known declination.

Traverse board

Developed as early as the 1500s, the traverse board comprises of a small board marked with the four points of the compass & eight holes bored at each point to represent each half hour period in a watch: this was used to peg the courses made by a ship in each half hour.

Backstaff

Invented in 1590, the backstaff is a navigational instrument that was used to measure the altitude of a celestial body, in particular the sun or moon. When observing the sun, users kept the sun to the back of them and observed the shadow cast by the upper vane on a horizon.

The sextant

The Longitude Act of 1714, offering the sum of £20,000 for the practical solution of the problem of the determination of longitude at sea to an accuracy of 0.5 degree, may have been the single greatest factor in establishing Britain as the world’s leading nation of navigators for almost a full century.

During the earlier years of the Board of Longitude, existing instrumentation was as inadequate for the accurate measurement of a Lunar Distance (the angle between the Moon and selected reference stars as the Moon moves against the stellar background) as was lunar theory for predicting lunar motion. The cross staff had come out of the East during the Middle Ages. The invention of the Davis quadrant (or back-staff) was over 100 years in the past. The simple quadrant and the mariner’s astrolabe were even less appropriate. Therefore, when John Hadley presented his new, doubly-reflecting quadrants before the Royal Society in the year 1731, a new order of instrumental accuracy was established. The sextant is a doubly reflecting navigation instrument that measures the angle between two visible objects.

Reflecting circle

Originating in 1758, a round brass frame with two wooden handles was developed to assist with navigation at sea. Named the reflecting circle, the tool allowed navigators to achieve superior accuracy through the use of a circle of 360 degrees, instead of the arc of 120 degrees as used by the sextant.

Modern-day navigational tools: offering first rate safety and outstanding productivity for ships

So, there are our top 13 navigational tools that have historically been used to navigate the globe. Congratulations if you managed to name 10 or more! If you succeeded, we think it’s safe to say that you’re an expert in historical navigation!

Leaving the past behind, thanks to advanced technology and the development of ECDIS, the best modern-day navigational tools offer first rate safety and outstanding productivity for ships and their crew across the globe. As the August ECDIS deadline is almost in touching distance, if you’ve not yet selected your preferred ECDIS provider, get in touch today to discuss market-leading iECDIS from Martek Marine.

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