Alright, me and another hiker planning to do the CDT this year have differing opinions on this. Of the Ley maps, GPS, Yogi’s book, and the Wolf books, what is it you really need? It is possible to just map and compass (and GPS) the whole way? And, how good are the guidebooks on water sources, trail finding, and town information?
wing it
My vote goes to the Ley maps with a compass and a lot of care. I didn’t need a GPS. I needed a small magnifying glass to read topo lines at times. Ley’s map notes were good for water sources, I found.
In my opinion, Yogi’s book is by far the best for town and resupply info and I thought it was well worth buying it and carrying the town maps.
Jim Wolf’s books are very good for much of the route, but they’re mostly written for a SOBO, and mostly cover only one route with very few alternates. The maps in the books are good for planning but mostly worthless for hiking. I followed Wolf’s route in Southern NM and needed extra BLM and USFS maps, since Ley did not go that way.
Consider the DeLorme atlas pages, too, for hitching and bailing out if needed.
There are some “official” guidebooks but they’re useful only for the coffee table and for driving directions for vehicle access.
Have a great hike.
Garlic
I would take all four!
The CDT is a navigational challenge if you are not a navigation genius. Therefore you should have as much information as possible and you will still get lost.
Ley maps are essential - there is no way around them. Their information on water sources are the most accurate - much better than Wolfe’s books that are a little bit outdated. We never trusted the water information in Wolfe’s books.
Yogi’s book is excellent for resupply planning - this book is well worth the money and will save you a lot of research.
Wolfe’s books are good as a second source - very often it took the combination of Ley and Wolf to figure out where I was. The maps in Wolfe’s book are useless.
A GPS is great because it will give you assurance that you are at the spot where you think you are. Yes, you can hike the CDT without a GPS, but it made me feel a lot more relaxed.
I took all four items and would do it again - if you absolutely want to safe money then skip the guidebooks or the GPS although I wouldn’t recommend doing that.
And although it would be possible to hike the CDT with just the Ley maps and a compass, I wouldn’t try to do that. Being lost or misplaced all the time spoils the fun.
I also had the Delorme maps but I never used them. I would not take them again.
GT
German Tourist