This week, I’ll finish talking about the important navigational items that I started discussing last week.

6. GPS

Global positioning systems have become incredibly popular in recent years.  They are so popular that I have actually met people that do not carry a compass in the backcountry.  I consider this practice dangerous.  Just like a compass has limitations and times when it will not function (near lots of metal for example), so too does a GPS.  I have been under canopy thick enough that satellite reception doesn’t happen.  Batteries also fail in the cold.

Don’t get me wrong, GPS is a great tool.  It provides a backup for your compass, and your compass provides a backup for your GPS.  GPS is like the modern version of the sextant, helping you to navigate by the heavens.

There are a variety of models available, but the things I look for in a GPS are very basic.  I’m not sure that any models do not have what I consider essential.  First, you need to be able to match your GPS to your map datum.  Second, you need to be able to work in meters / kilometers, because; third, you need to be able to use UTM.  UTM grids are in meters, pace counting math is easier when working in meters, and maps in most countries are denoted in meters.  Finally, I always look for a GPS that uses the same batteries as my other gear.  Matching batteries as much as possible reduces the amount of spares you need to carry, because you can share batteries among devices. My preference is something simple like Garmin eTrex H Handheld GPS Navigator.

7. Aerial Photographs

Google Maps has made it incredibly easy to view aerial photographs of just about anywhere on the planet.  Your topographic map can be out of date, sometimes dramatically.  Having a more recent view via an aerial photograph allows you to see the terrain before you actually arrive.  You can more carefully plot potential routes, potential alternate routes, terrain features to use as handrails and backstops when navigating, and possible sites of interest.

With some work, you can find objects on the photograph that you can use as a reference to add a map scale to the photo.  This can help you work back and forth with your map and your photos.  Another method I have used is to use a photocopier to resize a photo to the same size as the map.  Modern image editing software makes this much easier.

8. Topographic Maps

Last, but not least, is the topographic map.  This is arguably the most important piece of navigational equipment.  In many areas, it is possible to navigate entirely by terrain association with the map.   Purchase maps well in advance of your trip so that you have time to compare them to aerial photos, match the map datum to your GPS, set your compass to the proper declination, or look up the most recent declination value given a latitude and longitude from the map.

Just like with the aerial photo, studying your map allows you to plan your routes, determine terrain features to use to assist in navigation, find some locations that will likely be good campsites, or water sources, etc.  This is all very helpful when you are in areas that do not have established trails and campsites.

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2 Responses to “Navigational Tools of the Trade Part 2”

  1. Administrator says:

    That is a really useful site. Thanks for the link John.

  2. john hee says:

    Don’t know if you’ve ever come across this site. A great cross-over for checking the map to the ground for preplanning work

    http://wtp2.appspot.com/wheresthepath.htm

    Keep up the good work

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