Why Celestial Navigation

FOR ELECTRONIC BACK-UP 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. […]

How Does Celestial Navigation Work

1. Imagine that the sun is directly overhead at a particular time. Then we simply look into the Nautical Almanac to find out where the sun is; and that is where we are! 2. How do we know the sun is directly overhead? The sextant tells us. It measures the angle from the horizon (meaning [...]

Using a Sextant

A sextant is an instrument generally used to measure the altitude of a celestial object above the horizon. Making this measurement is known as sighting the object, shooting the object, or taking a sight. The angle, and the time when it was measured, can be used to calculate a position line on a nautical or aeronautical chart. [...]

Selecting a Marine Sextant

The first choice to make is between plastic or metal construction. Today's low cost metal sextants offer high accuracy and ease of use. These reward the beginner's efforts, and satisfy the professional's demands. Plastic models are perfect for lifeboat provisioning,and for restricted budgets. They are also acceptable to some experts who don't mind making frequent [...]

Choosing a Sight Reduction Method

"Sight reduction", is a term given to the way a sextant sight is transformed into a line of position on a chart. It is what the so called "math" concerning celestial navigation is all about. The simplest method of sight reduction is to draw a circle of equal altitude of a celestial body on an [...]

Choices in Plotting Tools

Beginners typically ask which plotting tools they need. It’s a good question, because the available range of tool types is greater than one would likely need. For example, parallel rules, rolling plotters, course plotters, triangles and plotting board pantographs all do essentially the same thing; that is enable you to draw a line in a [...]

About Artificial Horizons

Artificial horizons were used by sailors of sailing ships when they were becalmed. This condition was frequently accompanied by fog which obscured the natural horizon. A tray of mercury was used, and the image of the actual body was superimposed with the image reflected by the mercury. Half the angle was used as the sextant [...]

About Electronic Charting

Background. The world of electronic charting has seen a severe transformation in the recent past. First, NOAA released vector charts of U.S. waters free of charge to the public. These are called Electronic Navigation Charts (ENCs). Now they have done the same thing with Raster Navigation Charts (RNCs). These actions have changed the revenue and profit […]

How to Choose a Barometer

Even in these modern times of satellites and Internet, the atmospheric pressure measured with a personal barometer remains the most important indication of weather changes at your location. To evaluate present weather or forecast coming weather, we need accurate barometric pressure. Most common barometers on the market are not accurate enough to serve this purpose. [...]

Why Fujinon 7x50s?

The only two binoculars rated as SUPERIOR by Practical Sailor magazine, were the Fujinon Polaris and the Zeiss 7x50s (which cost about $500 more). In fact Fujinon was rated best in dim light conditions. Thanks to a proprietary zirconium oxide, electron beam coating (EBC) process, they are able to transmit an incredible 95% of the [...]