DAVIS MK 15/MK 25 PLASTIC SEXTANTS
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, and MK 15 (shown above) have the same basic construction. The
former is gray in color, and is said to be of a more stable plastic which
is resistant to temperature changes. The latter is black in color. The
MK 15 has a traditional split mirror, and is non-illuminated. MK 25 has
illumination and a whole horizon mirror. Both sextants come with an instruction
booklet, plastic carrying case, neck lanyard, 3x scope. and a sight tube. SW 7 lbs.
SPECIFICATIONS
| 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. |
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DAVIS MK 3 SEXTANT
This sextant will enable the beginner
to learn and practice the rudiments of celestial navigation at the lowest
possible cost. It is made of heavy gauge plastic with an adjustable half
mirror (which is equivalent to a traditional half silvered mirror). Although
it is without magnification or illumination, it can serve reasonably well
as a back-up emergency sextant. An optional carrying case (the same as
is shown for the MK 15/ MK 25 sextant) is available. (List price $55.99) SW 3 lbs.
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