Sextant is a device that was mostly used in the olden days by the mariners to find their route at sea for navigation guidance. They would trace the stars and as per the angular distance they would find the route.

The technique was simple and never failed the sailors. We will now discuss a little more on what is a sextant. The primary use of a sextant was to measure the distance between horizon and a celestial object.

This is why it became an important part of celestial navigation. The precision of calculation using this sextant were too good. This is because the horizon and the celestial body would never change location. The instrument was easy to use and anyone could learn to use the same.

I hope by know you have got a good idea of what a sextant actually is. We will now discuss how it worked and the mechanics behind it. This will help you to understand the concept of sextant better. It consists of a mirror that plays the most vital role in the navigation and judging the distances.

It was first invented by Isaac Newton. It has changed its form but is still more or less the same. The sextant basically calculates the angular distance between the celestial body and the horizon. After a certain interval the angle is again calculated. Some also maintain the record of the calculations. This helps the navigator to understand if he is on the right path.

There are two types of sextants and they are

1. Traditional sextant
2. Whole horizon sextant

Both these sextants give equally good results. We will discuss the same in more details. In the traditional sextant the view is basically divided into two. One side there is the horizon and the other side shows the celestial object. This sextant is very useful in the night when the horizon is not clear.

The other sextant that is called the whole horizon sextant is a little different. In this sextant a half silver horizon mirror is provided to do the navigation. This sextant is not very much in use. With the sextants the navigation and calculation depends completely on the mirror. The larger the mirror the better will be the calculation and the judgement.

Some sextants come with the feature of artificial horizon. This is particularly useful when the horizon is not at all visible. This happens in moonless nights and when there is too much fog. A fluid filled tube is used to understand the artificial horizon.

Some sextants have filters that can reduce the effects of the sun rays and the haze. A professional sextant is provided with various other features so that the navigation becomes easy. Some sextants can be water proof too. Many prefer the water proof sextants. The sextants are sensitive to temperature. As a result they can lead to miscalculations. This is exactly why weatherproof sextants are popular. These don’t get affected by the fall or rise in the temperature outside.

The sextant can give errors due to many reasons. Any measuring system for that matter can show calibration errors. This is exactly why from time to time the sextants must be checked to ensure that they don’t show any errors. The various types of errors that a sextant often shows are perpendicularity error, side error, collimation error and index error. All these error are common and must be checked. If not checked these can misguide.

You must be wondering that why we are discussing about a manual navigation tool in this age where there are such complex navigation techniques available. Well we cannot deny that in spite of all modern navigation techniques there may be a situation when the ship is lost. Due to bad weather the ship runs out of electricity.

The sextant as a navigation tool does not depend on any other source like electricity. It is independent and practical. No wonder it is uses as the best means of backup navigation technique in times of emergency. This is exactly why the sextant is still found in most of the ships. The captains and the other officials know how to use it even today.

The sextant is a good proof of the fact that no matter how much technology improves there are some basic things that will never change. Even today when a ship is lost, the captain has to depend on the stars to guide him. This is a brief idea about what is a sextant. I hope you have understood the concept well.