Are We There Yet? Reproducing the Back Staff Navigation Tool

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My Reproduction Davis Quadrant and Navigation in the 17th and 18th Centuries

Detailed instructions for building an accurate Davis Quadrant (also known as a back staff) are rare and difficult to find. To create my replica back staff, I consulted several books, including “The Voyages and Works of John Davis, the Navigator” (1880) by Coote, Jane, and Wright, which

Back staff in progress.

contains original diagrams and descriptions for this fascinating navigational tool.  In addition, I carefully studied a number of extant examples in museum collections such as the Mariner’s Museum in Newport News, Virginia and St. Augustine Pirate & Treasure Museum.  I was inspired by the elaborate design, the intricate measurements, and the potential for decorative touches such as bone inlays and decorative carving. 
 My goal was to create a period-accurate, museum-quality, working replica.




Joint and inlay detail.
Sight vane detail.
This replica was created with rich mahogany and maple woods, hand cut mortise and tenon joints, and hand-carved details.  Diamond shaped bone inlays were added to many of the joints for both stability and decoration.  It is not glued together; it is held together by the tightly fitting, precise joints. 

The completed back staff, ready to navigate into the 18th century!

I had so much fun making this reproduction that I made another one—this time in 1/8 scale, with a fitted presentation box. I call this my “Quarter Staff.” It’s a tiny, detailed, working  version of the original.




Just the right size for a Lilliputian sailor!
"Quarter Staff" resting snuggly in its case.





Back Staff History:


The back staff solved the problem of the cross-staff, 
Staring directly into the sun using the cross
staff could damage eyesight. Maybe that
gave birth to the "pirate eyepatch" myth!
which required the user to look directly at the sun. As you might imagine, this could at the least damage eyesight for navigators or even lead to blindness. To solve this problem, John Davis (or “Davies”) invented the back staff, also known as the Davis Quadrant, which uses the shadow of the sun instead of the direct view of the sun to determine its elevation. With the Back Staff, a navigator could look at the horizon and line up the shadow of the sun with the horizon at the same point on the instrument. 

Davis invented the instrument in 1594, and both he and others made a number of improvements to his original design, although it could not be used to measure the altitude of Polaris (the North Star) because Polaris does not have a shadow. The back staff became very popular and soon most sailors and navigators used it instead of the astrolabe or cross-staff. It was more accurate and easier to use at sea than either of those instruments, but would begin to be replaced in the mid-1700s by the octant or late-1700s by the sextant, which was even simpler to use and more accurate.

How It Was Used:


Period engraving illustrating the
parts and use of the back staff.

With your back to the sun, the observer adjusted the shadow vane (B) so that the sun would cast its shadow on the horizon vane (A). Sighting through the sight vane (C), the observer would adjust it so that the horizon and sun’s shadow aligned on the horizon vane (A).  Next he would read the scale of the shadow vane, add it to the scale of the sight vane and from this, determine the altitude of the sun. This number was used to obtain the observer’s latitude.
I ran across the image below online on a page describing early navigation. This is definitely NOT how you use this device!
Nope. Nope. Nope. 
Found this in a random search;
sorry, don't know who to attribute it to.
All watermarked photos and copy are copyright Jerry A. Hedrick 2017-2018. While pretending to be a pirate is fun, actual piracy is a crime. Please respect my intellectual property.




doctor chiropractor board license 

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