Davis plastic sextants have emerged as truly viable instruments for celestial navigation. Their accuracy is not as great as with metal sextants, and their errors vary with temperature, making frequent IC checks advisable. They make acceptable "first" sextants if finances are a constraint, and are always useful as back-up sextants. The MK 25(shown above) is gray in color, and is said to be of a stable plastic which is resistant to temperature changes. MK 25 has illumination and a whole horizon mirror. Comes with an instruction booklet, plastic carrying case, neck lanyard, 3x scope. and a sight tube.
- Arc -5° to + 120°, radius 178mm
- Accuracy Unpredictable
- Micrometer 1' scale, vernier 0.2'
- Mirrors 50x38 mm index,
- 42x29 mm horizon
- Shades 4 index, 3 horizon
- Weight 15 oz.