Celestial Navigation Software

A few days ago I purchased a celestial navigation program for Windows from http://www.tecepe.com.br/nav/. I am licensed to run this software on whatever computers I own (two on board at present). To use it I must enter the usual data for a celestial sextant sight, e.g. index error, height of eye, watch error, assumed position, name of body. These values remain in place until I need to change them, but for each sight I must enter the exact time of the sight and the altitude of the body above the horizon as read from the sextant (Hs) at that time. Instantly I get the numerical reduction results as well as a chart showing the Line of Position (LOP). I can wind up with a graph of the LOP's of that session's sights (of different bodies) to get a pictorial fix of the boat's location.

The software has other features such a superb star finder and a facility for printing out raw Nautical Almanac information for any day through the year 2050 so that I will still be able to do celestial navigation the old fashioned way without having to pay over $40 AUD every year for a printed version of the Nautical Almanac. That alone justifies the $40 USD that I paid for the software.

Procurement and installation of the software was a testimonial to modern commerce. I hit the "buy" button, supplied some information, and indicated that I wanted to pay via Paypal. A Paypal screen popped up, I made the authorization using my password, and within seconds I received an email from the company with the details of my purchased and the all important software license string. A second email delivered the URL location of the installation software. A third email was from Paypal confirming my finds authorization. I downloaded the installation software, executed it, and after about four mouse clicks the navigation package was installed and ready to use. The entire operation from the "buy" button to the "run" icon on my laptop took 10 minutes tops.

To use a laptop for celestial navigation seems like a contradiction. After all, the whole idea of celestial navigation is to be independent of electronic equipment that can be wiped out by such things as battery failure or lightning strike. But the way I see it elimination of the tedium of the computations associated with sight reductions will encourage me to take a lot more celestial sights which should lead to an improvement in the practicalities of taking sextant sights.

The Bowditch books still give me the ability to reduce sights with just pencil and paper. I have been learning from Bowditch how to do the required spherical trigonometry myself so that I will not have to use tables such as the HO-229. (I must learn to do this because the HO-229 tables that I have on board Pachuca go as far as 45 degrees, and the Horn is at about 56 degrees. )

Incidentally, I found the following entry in Wikipedia interesting:

"The US Naval Academy announced that it was discontinuing its course on celestial navigation, considered to be one of its most demanding courses, from the formal curriculum in the spring of 1998 stating that a sextant is accurate to a three-mile (5 km) radius, while a satellite-linked computer can pinpoint a ship within 60 feet (18 m). Presently, midshipmen continue to learn to use the sextant, but instead of performing a tedious 22-step mathematical calculation to plot a ship's course, midshipmen feed the raw data into a computer.^"