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Navigation compass: the backup that needs no battery or signal

By the Plain Prepper editors. Updated 2026-10-15.

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Quick answer

A navigation compass works with no battery or signal, which is why it belongs in a go-bag next to a paper map. A mirror baseplate compass such as the Suunto MC-2 has adjustable declination correction and map scales; a lensatic compass such as the Cammenga 3H is built for rugged sighting, with tritium lights Cammenga says glow for over 12 years. Whatever you buy, NOAA says to add the local magnetic declination to a magnetic bearing to get a true bearing.

Three compasses compared

Feature	Suunto MC-2 NH	Cammenga 3H Tritium	Cammenga Model 27
Type	Mirror baseplate	Lensatic	Lensatic
Declination adjustment	Yes, adjustable	Not listed	Not listed
Low-light marking	Luminescent markings	7 tritium micro-lights, over 12 years	Phosphorescent paint
Extras	Inclinometer, magnifier, metric UTM scales and inch ruler	Waterproof, sandproof, non-liquid needle housing	Same design as the military model, Cammenga says
Stated accuracy or range	Not listed on the product page	Plus or minus 40 mils, -50 to 150°F	Not listed separately
Made in	Finland	USA	USA

Details are from Suunto's and Cammenga's product pages, checked October 2026.

Declination: the correction most people skip

• What it is: NOAA defines magnetic declination as the angle between magnetic north and true north; it is positive east of true north and negative when west.
• It changes: NOAA says declination changes over time and with location, so look up a current value for your area with NOAA's calculator.
• The math: NOAA says you compute a true bearing by adding the declination to the magnetic bearing. With a declination of minus 10 degrees, a magnetic bearing of 90 becomes 80 degrees true.
• Set it once: a compass with adjustable declination correction, like the MC-2, lets you dial it in so the compass reads true bearings directly.
• Near the poles: NOAA warns declination is unreliable close to the magnetic poles.

Baseplate or lensatic?

• Baseplate: the clear plate lays on a map for plotting; Suunto lists metric UTM scales, an inch ruler and a magnifying lens on the MC-2.
• Mirror sighting: the MC-2's mirror lets you sight a distant landmark and read the bearing at the same time, and doubles as a signal mirror, Suunto says.
• Lensatic: a folding sight and lens for taking bearings on distant objects; Cammenga says its compasses are made for the U.S. military.
• Durability: Cammenga lists the 3H as waterproof and sandproof, with a non-liquid needle housing it says is not affected by temperature changes.
• For most people: a mirror baseplate compass is easier for map work; a lensatic suits rough use and night sighting.

Hemisphere balancing

• Why it matters: Suunto says the Earth's magnetic field is not even between the poles, so needles must be balanced to stay level.
• Zone needles: a two-zone system balances the needle for the northern or southern hemisphere; the MC-2 NH is the northern version.
• Global needles: Suunto's global variant uses a needle and magnet that tilt independently to work anywhere.
• U.S. buyers: an NH compass suits North America; travelers to the southern hemisphere should choose a global version.
• USGS variants: Suunto also lists MC-2 versions with USGS map scales.

Practice before you rely on it

1. Look up declination for your area on NOAA's calculator and set or note it.
2. Take a bearing to a landmark you can see, then walk it and check you arrive.
3. Orient a paper map of your area with the compass at home.
4. Keep it away from metal and electronics when taking a reading; NOAA notes the needle follows the local magnetic field where the compass is.
5. Store with a map in your go-bag; see our bug out bag list.

Low-light use

• Tritium: Cammenga says the 3H's tritium lights are self-powered and need no recharging, lasting over 12 years.
• Phosphorescent: the Model 27 uses phosphorescent paint instead, Cammenga says.
• Luminescent markings: the MC-2 has luminescent markings for low light, Suunto lists.
• Headlamp: pair any compass with a red-light headlamp; see our rechargeable headlamps guide.

What to look for when you buy

Questions people ask

What is magnetic declination?

NOAA defines it as the angle between magnetic north and true north; it changes with time and place.

How do I convert a magnetic bearing to true?

NOAA says add the declination to the magnetic bearing, using a negative number for west declination.

Baseplate or lensatic compass?

Baseplate for map work and easy declination setting; lensatic for rugged sighting and night use.

Does a compass point to the magnetic North Pole?

No; NOAA says it follows the local horizontal magnetic field where the compass is.

Sources

• SUUNTO MC-2 NH Mirror Compass, Suunto
• Tritium Compass 3H, Cammenga
• Phosphorescent Lensatic Compass 27, Cammenga
• Magnetic Declination, NOAA National Centers for Environmental Information

Sources checked 2026-10-15.