Davis Mark 15 Master Sextant

The Davis Mark 15 Master Sextant is a precision celestial navigation instrument designed for maritime navigation, offshore operations, and field navigation where GPS is unavailable or unreliable. Built by Davis Instruments, a leader in marine navigation tools, the Mark 15 delivers the optical precision and accuracy required for autonomous position-finding in open water and remote terrain.

This sextant features a 7-inch (18 cm) frame radius graduated from 120° to -5°, enabling measurement of celestial bodies across a wide angular range. The micrometer drum vernier scale reads to 2/10 of a minute—equivalent to roughly 0.0033 degrees of arc—providing the sub-minute accuracy necessary for reliable latitude and longitude fixes. Seven large sunshades protect the optics during solar observations, critical for maintaining sight clarity in harsh sunlight. The 3 mm × 27 mm star scope delivers sufficient light-gathering power and magnification for star identification during twilight observations, when most celestial sights occur. A traditional half-silvered mirror balances direct sunlight observation against horizon visibility, a design refined over decades of maritime use.

The Mark 15 serves maritime crews, naval personnel, offshore surveyors, expeditionary teams, and emergency navigation specialists who require proven mechanical navigation capability independent of electronic systems. Weighing 3.45 lbs with compact dimensions of 11 × 5 × 13 inches, the instrument balances optical capability with portability for shipboard, aircraft, or field use. The included instruction booklet provides setup and observation technique guidance. This is the tool professional navigators choose when accuracy and reliability cannot depend on satellites.