Seafarers, since the beginning of time, have used their observations of wind, waves, currents, bird migrations and more to understand how to get from one place to another over the oceans of the world. It is clear that stars and other bright objects in the sky, including the sun and the moon, have been utilized for purposes of navigation. Though the early sailors had some crude instruments they weren’t always necessary. The rising and setting of the sun and moon helped provide some direction provided that seasonal adjustments were understood and made before setting sail. True North, or at least an approximation within about 2%, could be sailed by sailing to the North Star in latitudes in the Northern Hemisphere where the star is visible.
We could board my boat now, after having prepped for a few weeks on the ocean, head southwest, sail southwest until the star Arcturus was directly overhead, turn to the west, follow the star nightly sailing with it as it crosses the sky, maintain the direction during the day, correct at night when the star is visible and, ultimately, we are going to be in Hawaii. We almost wouldn’t need a compass. Just the star, some accuracy in helmsmanship, faith, and patience.
Mankind has always sought to do better. Improve accuracy. Sail the shortest route. We have a need to know precisely where we are at almost any moment in time. A “position” or fix of any type is much more comforting than a random guess. Ailing close to shore, we are able to use visual cues to navigation and radar to obtain our position. In the middle of the ocean, if your chartplotter is not functioning, options for determining a fix are limited. One could, using speed and time determine distance sailed. Or, one could read the ships log connected to a knotmeter that provides a reasonable approximation of distance traveled to get an idea of distance. Combine this distance with magnetic direction steered, if you’re fortunate enough to maintain a constant heading, and one can plot a series of points and connect them with a line to estimate travel and position in the ocean. The main problem with this approach, even if it has been accomplished with utmost care, is that ocean currents and wind blowing the vessel a little sideways can seriously affect ones position. As a result, sailors have always looked for ways to pin down wheee one is at any time on the globe. Middle Eastern peoples who crossed expanses of land many centuries ago knew to use the heavens to find their way. Over the course of time, our understandings of Earth science, astronomy, spherical geometry, and an evolving ability to craft precision instruments with the very best optics, micrometers, and mirrors have paved the way for modern day celestial navigation. In this day and age, all one needs is a good sextant, and a few books with tables, and along with a fair bit of understanding and one can use the sun, moon, stars, and a few planets to determine ones location on the globe with sufficient accuracy to feel confident that one is either on course and should continue as planned or develop a change in sail plan to get back on course to ones destination.
Club Nautique provides an excellent course on Celestial Navigation. It encompasses three weekends. The last weekend is spent in review and test taking. The lectures are superb. There are practical exercises wherein the class reduces sun sights. The classroom work also involves practice sessions with example questions. You will learn to do running sights combining a sun sight with other sights to determine position.
One is not required to purchase a sextant for the class. I do, however, recommend that you obtain an excellent one if you intend to sail more than 50 miles offshore on a regular basis or cross oceans as part of your adventures. It’s also a good idea to have a sextant so as to occasionally practice what is learned. I didn’t buy one but I intend to do so at some point. I think it’s a nice thing to have for use when one might truly need it. Preparedness is essential.
The book that was recommended at the time I took the class was next to useless. I recommend the book depicted below. It will teach you a lot of fascinating things about the globe, the sky and it’s objects, and help you understand the details of all of the different sight reductions so that you can find your position on the water.
Perhaps you’re not really interested in learning celestial navigation. I would recommend at least reading through several chapters in the book and parts of the chapters pertaining to sight reductions. Doing so will indeed be worthwhile and you’ll be able to improve your vocabulary and fill your head with knowledge that may be somewhat useful. For example, did you ever wonder why the sun is not precisely over your head when the clock shows noon? How can you determine when the sun will be directly overhead? How may degree does the sun scribe across the earth as the earth rotates for an hour? Why do stars stay at their same latitude during the different seasons but the sun crosses the equator creating different seasons in the Northern and Southern Hemispheres? How far north on the surface of the earth does the sun reach in our hemisphere during the year? On what day does that take place? What is civil twilight? Go find the answers to these provocative questions and more. There are plenty of fun facts awaiting you.
At the very least, learn to find the North Star (Polaris) and how to determine true north. This ability may save your life if you’re ever lost.
You may also find these two books useful.