NEW ASTRA 3 B DELUXE SEXTANT AUTHORIZED DEALER GUARANTY

The manufacturer's literature states that the Astra IIIB has revolutionized the metal sextant market by introducing a high quality, accurate, metal sextant at a low price. Over 13,000 sextants of this model have been sold in the US alone in the past 15 years; far more than any other serious sextant. Its popularity has spread throughout the rest of the world as well. It is easy to see why. The sextant has the looks and feel of a fine piece of precision engineering and is detailed to a very high standard all around.

The frame is made from lightweight aluminum alloy which resists corrosion. Aluminum alloy is not new to sextant construction. It is currently used by Tamaya, Freiberger and by C. Plath for a lightweight version of their famous Navistar Classic sextant. The Astra sextant is electrically lighted by LED on the arc and drum. Batteries NOT included. Its low price, excellent optics, and choice of horizon mirrors and other accessories makes it a good choice for beginners and professionals.

The Manufacturing

The Astra IIIB is made by the Changzhou Celestaire Instrument Co. in China and is subject to stringent testing. For example, each mirror and shade glass is tested for perfect flatness by the Fresnel diffraction pattern method. The sextants are assembled and tested in a clean, professional, environment. Random units have been tested by us and several professional navigators, with results that rival the most expensive German and Japanese models. 

The Astra IIIB is seen in two models: standard and deluxe. The difference is in the index mirror. The Standard model has a round index mirror with the silvering applied to the rear surface of the glass. It has less surface area, and is not as good for twilight use. This is the way all ASTRA IIIBs were before 1994. At that time the Deluxe model was introduced with a rectangular index mirror having the silvering applied to the front surface (the mirror is interchangeable in size with most other full size rectangular mirrored sextants). From an engineering standpoint, this arrangement allows for a larger reflecting profile during high angle observations, and better reflection brightness for all sights. Such improvements, are more easily noticed by the user doing twilight star and planet sights. From a practical standpoint, the biggest improvement is in durability of the silvering itself. When applied to the front surface. it is easy to keep clean and free of saltwater contamination. It is further protected by a durable oxide coating. In contrast, rear silvered mirrors need resilvering more frequently if saltwater becomes trapped between the mirror and its housing and is not faithfully rinsed out.

The horizon mirror for this unit is the whole horizon (WH) type) which is felt by many to be easier to use and longer lived, and is a costly option on other sextants with which the Astra competes.

It has nothing to do with the accuracy of the sights taken with these instruments, but the quality of the case and its fine furniture finish is another indication of the care that goes into the manufacturing process.

For purposes of judging whether my opinion counts, I was the editor of the chapter on sextants of the 1977 Edition of "Bowditch", The American Practical Navigator, NAVPUB 9; a member of the U.S. Naval Academy Navigation Symposium Board, 1975-1978; the author of a book on marine sextants, Cornell Maritime Press,1975, and the founding president of Nautech Maritime Corporation which partnered with Tamaya of Japan in the introduction of the MS 733 Spica, the MS 833, Jupiter, MS 933 Venus sextants and the famous NC-2 navigation computer, in the U.S. market. I  am also a retired Master Mariner, and held a U.S. Navy "D" Qualification as a Senior Skipper - Oceans.

Included and Optional Equipment

The sextant has LED lighting of the arc and drum powered by two standard size AA batteries (not included) which install in the handle. It comes in a varnished wooden case, with instruction book, certificate of accuracy, vial of oil, and adjusting wrench. It includes a 3.5x40 monocular telescope as standard equipment.