Wednesday, March 21, 2018

CDT Maps

For anyone searching for maps for the Continental Divide Trail, this is the wrong place.  What I want to talk about are my plans for navigating the CDT this year.

First, I want to say that I actually like paper maps.  But they have their shortcomings.  First of all, you have to carry them.  And if you are going a long distance, you need lots of map pages.  They need to be survivable in rain, and you need to be able to retrieve them from your pack as you transition from one map to another.  On a thru-hike, they are just a real pain.

Then there is the difficulty in actually using them.  If you only use a compass, even a good topographic map is going to be problematic.  If you continually update your position on the map, as you climb, descend, and go around topographic features, you are likely going to have your position correctly plotted.  But then again, maybe not.  Ridges and peaks all look fairly similar.  If you don't have a couple of features you are sure of, you can easily think you are somewhere where you are not.

So I carry paper maps as backup, usually at a scale that minimizes the amount of paper I have to carry.

For the past several years, I've used GPS receivers.  And lately, I've been relying on my iPhone.  There are a lot of good GPS mapping apps:  Gaia, Guthook, etc.  But they didn't do everything I wanted, so I wrote my own app, Hikers Assistant (you can find it on the Apple app store).  The other apps have improved since my first version, and they now do a lot of what I originally wanted, but they still don't do everything I want a mapping app to do.

Hikers Assistant lets me create my routes and waypoints during trip planning.  Then on the trail I can find the closest point on my route (trail) and its direction.  I can also find the distance and direction to an ordered list of waypoints, with the closest being listed first.  And the app only turns on the GPS when its needed, so it uses very little power (battery).  I can load the 3,000 mile CDT trail in my iPhone, which I would carry anyway, and its always in my pocket, ready to be used.

Since this isn't an ad for my app, I won't mention all of the other features.  What I wanted to do in this post was describe my trail navigation preparations.

I started by buying the Bear Creek maps and downloading their lists of waypoints.  The waypoints highlight key turns and route features, but they are not really close enough to represent the detail on a trail.  Still, I converted the waypoints to a route.  Then in my app, I opened Thunderforest Outdoors and Open Cycle maps and traced a lot of the CDT between the waypoints.

Neither Bear Creek nor the CDT Coalition sell or make available the actual GPX routes they use on their paper and PDF maps.  Though somehow Guthook seems to have acquired the data for his app.  And the few hikers that posted their routes from years ago either stopped supporting their web pages or simply have not updated the routes to match the current official trail.  So my pseudo-routes will be a bit of a navigation challenge.

To my routes I added the Bear Creek waypoints (they are still useful by themselves) and I also converted the CDT Coalition's water report into waypoints.  Beyond that, I've added resupply waypoints from Yogi's CDT Handbook.

I've also downloaded offline map tiles for USGS Topo, USGS Imagery, Open Cycle and a couple of other map sources.  I plan to enhance that with downloaded maps for towns (in case I don't have connectivity), and I will overlay park maps for Yellowstone and Glacier National Parks.

I've considered taking a second iPhone as a backup, but probably will not do so.  I will have a Garmin inReach Explorer with me, though it cannot hold the complete route or anywhere near it.

I also have purchased the Guthook app with the CDT maps.  I will have Gaia.  And I've downloaded some of the older Ley maps for Avenza.  The one thing I expect to use fairly frequently in addition to my own Hikers Assistant is the Guthook app.  It has a great list of water sources that isn't really covered by the CDT Coalition's water report--which focuses on the drier sections of the trail.

I've kept busy and enjoyed the process.  I've also spent a lot of time I probably didn't have enhancing and upgrading Hikers Assistant.  I would like to mention that I've made my routes (as Hikers Assistant *.trdat files) available on my website (  These do not include the Bear Creek waypoints, as I've tried my best to address copyright restrictions.  Hikers Assistant can now send out progress waypoints (breaks, camp sites, etc.) to friends and family.  They in turn can use the CDT routes from my website as trails in Hikers Assistant upon which to plot those waypoints.

And pressure is really building to complete my preparations...

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