-  remember, anything less than 7 inches is practically unusable -

Great as a demo model or for someone wanting to to learn how to use a sextant. With instructions on how to use. Great for collectors and shops selling nautical goods.  An antique brass sextant of the same dimensions and features costs upward of $2000.

          Range of angular indications: 0 - 120o
          Instrumental error: no more than 12"
          Dial scale division: 1o
          Drum scale division: 1'
          Reading error for drum scale: 6"
          Correction to sextant indication: 36"
          Backlash between worm screw and frame: not over 12"
          Galilean telescope ratings:  magnification 3x-4x,  field of vision 4o30 - 6o40
          Mass of sextant, kg:   less packing box 1,5,  with packing box 4,5
          Overall dimensions of sextant with Galilean telescope, mm 300x228x137
          Overall dimensions of OPTIONAL packing box, mm 278x275x160

Two telescopes, the conventional 4x and a high power chromed brass 10x scope. The 10x power scope is used for sun sights. they are also excellently suited for taking vertical and horizontal sextant angles of terrestrial objects

This is a beautifully callibrated piece. Nine out of ten sextants being sold on ebays are decorative or sentimental crap so be careful when you invest in something that merely looks good or is promised as "uncallibrated but functional" (whatever that means!). On sale here is a beautiful and fully functional ZWEISS sextant, each with a unique serial number, and with .pdf instructions on how to use. A very high-quality teakwood carrying and display case weighing over 3 lbs is provided free with the setant. The brass is powder-coated ( far better option than lacquering) and this makes it look extremely authentic and also eIiminates the need for regular polishing. I have very few units of this model so whether you are a serious collector of classic sextants or own a store, this one is for you at our guaranteed unbeatable factory prices..

Some Sextant Basics
(excerpts from the manual) 

A sextant is a very important mathematical instrument for navigating at sea. It can also be used in astronomy. It is used to measure the angle between two far away objects. Most often these objects are the sun and the horizon, or the pole star and the horizon. Sometimes the angle between the horizon and stars or the moon can also be measured with a sextant.

The original Ross London sextants (on which this replica unit is authentically based) were made in England at the end of the 18th century. The biggest problem for sailors in the 18th century was finding their position in the middle of the oceans during long journeys. Sailors needed to be able to find both their latitude (which was their position north or south on the earth) and their longitude (which was their position east or west on the earth). Sextants helped them to find out both of these things. Before the invention of satellites and electronic satellite navigation systems it was very hard for sailors to find their position at sea. Many shipwrecks occurred because captains got the positions of their ships wrong. This not only caused the deaths of many seamen but also had big political and economic implications for the government because lots of battles happened at sea or valuable cargo could be lost in shipwrecks.

Sextants are made with a circular curve that is one sixth of a circle. The curve is divided up like a protractor. It is used for measuring angles so it is labelled with degrees. The other important parts of a sextant are a telescope, a piece of glass which is half see-through and half mirror (called the horizon glass), and a moving arm which has another mirror fixed to it.

 In earlier times, marine sextants had a fixed telescope leveled on the horizon and a radial arm is moved against an arc scaled in degrees. The radial arm is adjusted to get the reflection, of a known star, from index mirror and then off the horizon mirror down the telescope until it lines up with the horizon. The position of the radial arm on the scale gives the stars elevation. The nautical sextant range includes: slow motion nautical sextant, octants, slow motion nautical sextants and round dubble telescope nautical.

In modern navigation sextants, the light ray from the celestial body is reflected in two mirrors (in series) one of which is adjustable and the other is half silvered. By rotating one mirror and its attached index bar, the image of the body is brought down to the horizon. The rotation measures the altitude on the limb.