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Why Celestial Navigation



GPS is wonderful. World-wide coverage and reasonably priced receivers (both installed and handheld) contribute to maritime safety through accurate positioning of vessels. Yet, some back-up is needed.

Instances of electronic failure, total electric failure, lightning strike, and flooding are often documented. Even battery powered handhelds can be rendered inoperable in these ways. Batteries can run down, spares can be lost. The GPS system itself is not guaranteed to always be in operation.

The best possible primary/back-up system combinations have these four characteristics in common:

1. They have independent power supplies.
2. They receive data from different sources.
3. Each system verifies correct operation of the other.
4. The back-up system is used – not left dormant until needed.

Celestial / electronic is the only navigation combination that meets these requirements.


GPS will track your boat, steer your boat, and wake you up in the morning. Some say it will even take your boat across the ocean for you. Without establishing a discipline, one’s navigational skills (and for that matter helmsman skills) will be jeopardized. The key to safe passagemaking navigation is the time-proven DR track. It should be maintained and updated with fixes, whether electronic or celestial. This yields valuable information about current set and leeway, and steering and compass errors which will be needed in the event of a navigational emergency.

A good discipline to establish involves turning off the GPS for extended periods of time (except for periodic checks), and navigating celestially. This hones navigational skills, yields the desired DR track, verifies correct GPS operation, and keeps your back-up system tuned, verified, and ready to rely on if needed. Your reward will be a well kept chart and log, an understanding of the forces affecting your passage, and pride in navigational accomplishment.


Tradition is not for everyone. There are pragmatists who reject unnecessary activities out of hand. Yet most professionals revere the traditional as well as the modern.

Who can contemplate an 18th century brass and ebony sextant and not wonder what it was like to peer through it at the heavens, and bring an evening star down to a twilight horizon from the deck of a tall ship? To sense the approval of those who witness this magic-like prowess. To triumph at a land-fall well predicted? To know he can navigate any ocean with no help from anyone?
The sextant (and its predecessors) is central to the history and tradition of sailing. Its image is used in logos, letterheads, and media publicity however connected with sailing. Authors appear with them on dustjackets. Good sailors appear with them on deck.


Fun is doing something that is both easy and difficult. Easy to get started with, like playing chess or hitting a golf ball; but having enough depth that mastery does not come easily.

What could be easier than reckoning the longitude by simply observing the time of sunrise or sunset, or steering by a star? Almost as easy is the finding of latitude at noon. But how about identifying the navigational stars? Recognizing the planets? Accounting for the parallax of the moon? More experienced celestial navigators can use an unknown star shot through a hole in the overcast, shoot planets in broad daylight, predict sunrise underway, and calculate great circle distances.

Being familiar with the night sky is like having a giant roadmap overhead. One star may be over London, another the Azores, and the moon over San Juan. All showing relative distance and direction from you. It connects you back to the world in a way that diminishes the sensory deprivation of a featureless sea.
People enjoy using sextants; even from a backyard with an artificial horizon. It’s one of the few nautical activities that can be done without a boat, or even getting to the water.

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