Course objective: Use a sextant and celestial objects to find one’s position.
Pre Course Experience: None
Assumed knowledge: None
Duration: 5 days theory, 1 day practice
What I will learn
- History of Astronomy and early celestial navigation
- Principle of Astronomy \ circles of positions
- Spherical trigonometry
- Sextant handling
- Sight taking
- How to read an Almanac
- How to find one’s position by noon sighting
- Sight reduction techniques
- Understanding time (UTC time, sideral time …)
This is a course for anyone serious about sailing. Celestial navigation is an important skill and is still taught today even though GPS have become so convenient and affordable. Even though the GPS system (and other similar services) are reliable, we are still at the mercy of solar flares which can disrupt permanently any satellites (as it nearly happen, by 1 week in 2012 according to NASA) and/or lightning strikes which will disable any electronic equipment on board.
At the beginning of this course, we will take a trip back in time and start our journey of the stars with the first greek astronomers. We will pay respect to Eratosthenes and Aristarchus for their brilliant intuition and mathematical genius in discovering that our planet is a sphere and not at the center of the universe, more than 2000 years before Galileo and Copernicus. We will explore the first methods for finding a position using stars and how celestial objects locations in the celestial sphere were recorded in almanacs. On the way to modern times, we will salute Sumner and St Hilaire for giving us, back in the mid 19th century, the 2 main methods used for sight reductions today.
For those of you who have not done any spherical trigonometry since high school, don’t worry, we go back to the basics and re-explain the sine and cosine laws for planes and spheres (high school 10th grade). These laws are used throughout the course and it is important to understand how they are useful to calculate the length in degrees between 2 points or to calculate an angle (to compute an azimuth for instance or a longitude).
Our school has several sextants for students, from simple Mak 3 sextants to the very powerful and precise Astra III and Tamaya They will be used for noon/sun sighting during the day and star altitude observation at night.
We will then explain how to read an almanac to extract the Geographic Position of the observed celestial object, do all our fine tuning by including all the necessary corrections like dip, altitude, sextant errors …
From the almanac readings we will have a correct GP of celestial objects which will then be used with either pure trigonometry or using sight reduction techniques (a semi-graphical method) to obtain our position. Et voila !
Before finishing, we will look at “time” and awe at its complexity. We will learn about Aphelion, Perihelion, Analemma, Equinox, Solstices, the path of the Earth around the sun, the difference between apparent solar time (used by ancient Greeks with their gnomon), mean solar time (used by you and me with a watch) and sidereal time (used by astronomers). And you will finally understand why we constantly need to adjust our watches because a day is not really 24 hours !
Book your course now :
Palawan Sailing courses start at 9:30am and finish at around 4:30pm.
We have a maximum of 4 students per boat and a minimum of 2 students. It is recommended that you contact us to book your course.
Call +639 060185714 (please remember the time difference with the Philippines : UTC/GMT +8 hours) to inquire or book or use our contact form.