NAVIGATOR Field Procedures.

Condensed from the EmNav NAVIGATOR field manual. Practice before you need them. Cross-check every result.

Pace count
Set your 100-meter pace on D scale. C scale becomes distance; D scale remains paces. Example: 53 paces / 100 m. Seventy-five paces reads about 141 m. Two thousand meters is about 1,060 paces. Tighten the center screw so the disks do not slip and walk the index arm around the C scale as a running tally.

Time, distance, speed

Distance = speed × time. Set 1 on C scale over speed on D scale; read time on C scale against distance on D scale. A 12-mile ruck in 2.5 hours is 4.8 mph. At 2.6 mph, 36 miles is about 13.9 hours. Infinite scale -- the circular scale does not run off the end of the rule.

Map scale
1:50,000 map scale — set C-arrow to '5'; 3.2 cm on the map i= 1.6 km on the ground. 1:24,000 map scale — set 2.4. Roll the outer 360° edge as a map/route measurer: 19.25 ticks per inch, 7.58 per centimeter. On a 1:50,000 sheet, one tick is 66 meters.

Deliberate offset
Your leg is 156° for 600 m. You offset right 10° and walk the new azimuth of 166°. At the end of the pace count the scale says turn 95° (never a clean 90) for 104 m to the intended point. LARS: left offset, add; right offset subtract. Night: one click on a Cammenga bezel is 3°; a comfortable offset.

Noon-sun latitude
Disassemble if the center screw fouls the plumb bob. Gnomon in the gnomon hole, weighted string in the plumb hole. Align the gnomon shadow across the 0s at LAN. Read altitude. Latitude = 90 − (altitude ± declination). The disk clinometer is the fast method. For a tighter sun altitude, the BREES uses optical glass plates and a micrometer. Polaris altitude is latitude, within about 0.8°.

Moon compass and illumination
A full moon is a night sun, offset twelve hours. Full-moon dates are the black dots on the declination / Equation of Time plot. Illumination: days since full moon × 7% on C scale and D scale. Waxing after new, add. Rough, fast, good enough to make a decision.

Vehicles and magnetics
Step away from iron and steel before you trust a magnetic azimuth you intend to feed the sun compass. E-bike 10–15 m. Car 30 m. Truck 40 m+. Military armor farther. The sun compass does not care about the metallic hood. The compass needle does.

Improvising the disk
A circle whose radius is 57.3 units has a circumference of 360 units. Each unit on the rim is one degree. Knot a string, cut a stick, scratch bark. The NAVIGATOR is also a teacher: once you understand the geometry, the hardware is optional.