The Stanley London Mark 3 Sextant represents the best quality marine sextant available on the market for the price. This isn’t a reproduction, but an accurate and calibrated fully functional nautical sextant for marine navigation. There’s a very minor sacrifice in potential accuracy (+/- 20 arcseconds all over the arc, compared with +/- 10 to 12 arcseconds), which is inconsequential compared to the human error when taking sights from a moving small vessel. This Mark 3 is in reality used by many professional navigators. The Mark 3 sextant has revolutionized celestial navigation: Never before has this type of high-quality, accurate metal sextant been to be had at this type of low price. The sextant’s full 50 mm mirrors and shade glass are precisely machined and extensively tested for flatness the usage of the Fresnel diffraction pattern method. The Mark 3 sextant’s LED lighting of the arc and drum allows for convenient night sights. Two standard AA batteries fit in the sextant’s care for (batteries not included), and a convenient thumb switch controls the lighting. The 3.5 x 40 scope has fully coated optics and a large 40 mm objective lens to yield a sharp 3.5-power non-inverted (upright) image. The sextant comes with a beautiful, top of the range hinged hardwood case to store and protect the instrument. This sextant has a unique serial number and is fully functional and factory calibrated for navigation.
The Mark 3 Sextant uses a lightweight, corrosion-resistant aluminum alloy, just as Freiberger, Tamaya, and C. Plath do in their lightweight sextants.
This aluminum-alloy instrument at only 2 pounds, 8 ounces (1.13 kg) is easier to use than the traditional 4-pound brass models.
The sextant is 9 3/8 inches (23.8 cm) wide, 9 inches (22.9 cm) tall, 5 1/4 inches (13.3 cm) deep.
The sextant case measures13 inches (33 cm) wide, 10 1/2 inches (26.7 cm) deep, 6 1/4 inches (15.9 cm) tall.
The Stanley London Mark 3 Sextant includes top of the range sextant oil, an adjusting wrench, a brush, lens cloth, and a Quality Certificate specifying the sextant’s +/-20 arcsecond accuracy all over the arc.