Click image for a 'Guide to Parts'.

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Full-size vernier sextants were, in skilled hands, instruments of great accuracy, practicality and beauty - a joy to own and use, but also essential to the safety of the ship. Our replica is dedicated to Royal Navy Captain John Campbell, who developed the instrument from its predecessor, the Octant, in 1757. Crucially his invention was close in time to that of accurate, portable chronometers, and it was the combination of the two which finally made navigation a science rather than guesswork, saving countless lives.

This importance gave rise to the air of mystique which surrounds the instrument and its use, even in today’s age of electronic wizardry. Detailing is impressive, with hardwood handle and protective box, six shades of varying intensity, and a powerful telescope.

What does a sextant do?

It is a common misconception that a sextant "tells your position" when, in fact, the only information that can be obtained from it is an angular distance between two objects.
, most often (in position finding) the sun and the horizon. Obtaining this angle is called "taking a sight".

Removal from the box:

The sextant is a delicate and finely-tuned instrument. When handling, it is important not to touch the mirrors or index arm, which are easily knocked out of alignment. We recommend that it is removed from (and returned to) the box by gripping the body, through the large circular holes. Once out of the box, the weight of the instrument should be carried by means of the wooden handle (A) on the reverse or the support feet (B) if laid down.

To take a sight (assuming observation of the sun):

1/ Remove the replica sextant from its box and lay flat on a convenient surface.

2/ Adjust the index arm (C) by rotating the index pinion (D) so that the vernier scale (E) reads 0 degrees. (More info on this with accompanying product details).

3/ Position one or more filters in front of the index mirror (F) and one or more filters over the horizon glass (G). There are three shades in both positions, which can be used singly or in combination.

4/ Hold the sextant in the right hand, by means of the wooden handle, so that the telescope (J) is near to the right eye, with the arc (serrated edge) facing downwards. The telescope focus is adjusted by sliding the eyepiece (K) in and out of the main housing.

5/ Align the sextant so that the horizon in the direction of the sun appears through the telescope.

6/ Rotate the index pinion (D) until the upper or lower limb (explained in accompanying notes) of the sun appears to line up with the horizon.

7/ Read off the angle from the Vernier.

Note: the above guide is a shortened version of accompanying printed paper notes where there is considerably more explanation including 'How to read a vernier scale', 'Index Errors', 'Care', 'Safety notes'.

Dimensions - Instrument 8" x 6.5", Box 10" square.

NOTE: Our replica instruments are complete in all the parts and are intended to show how the originals would have worked, but are not intended for serious use.

Delivery to: UK, USA, Canada, Australia, Austria, Belgium, Brazil, Denmark. France, Germany, Greece, Greenland, Ireland, Italy, Japan, Netherlands, New Zealand, Norway, Portugal, Spain, Sweden, Switzerland.

P+P ADDED AT CHECKOUT (Some non-uk destinations may require an additional delivery charge for heavier items).