It is possible to navigate the whole route using way markers and the route description from the guide. But if the TMB is anything to go by, the way marking will probably border on vandalism in easy to follow sections and disappear for long stretches in the mountains.
Cicerone publish a set of updates to their guides on the web site.
Although some people do the HR using just the Kev Reynolds guide book, to me, a map is essential even if the trail is well marked. I’ll be carrying two of each (well, LB will have one copy). Anyone that’s walked with us will know our bad habit of wandering off trails to do other “interesting bits” so anyone walking with us is well advised to carry their own maps.
Swiss Topo produce two maps that cover the whole route (offset from their main mapping to do so). They’re both 1:50000: “5003 Mont Blanc Grand Combin” and “5006 Matterhorn – Mischabel“. I did consider getting 1:25000 scale maps (it’s more that I like maps than wanted the detail!) but it would take nine to cover the route.
I’ve always used the The Map Shop for foreign maps but a supplier of Swiss Topo maps local to your own country shouldn’t be hard to find on the Internet.
Map cases drive me mad so I send them to Aqua3 for coating. It’s not cheap but it makes them just about indestructible and has also got people approaching me to ask where I got maps, that they’d only previously seen as plain paper, in what appears to be a plastic version. A good conversation starter – as long as you can speak the language!
Again, to me a compass is essential and if you’ve got a map then you really need a compass to be able to use it fully. I also carry a spare, not just because they they’re small enough to lose easily but I’ve also known someone trip and ram their compass into rock!
But it’s expensive so I carry a Field 7 for a backup (24 grams).
I’ll be carrying a Garmin Gecko 301 (87 grams). Although I’ve navigated for hours in visibility so poor that I’ve had to throw little snowballs a few feet ahead of me to be able to focus on something it’s a pain if you’re tired and everyone’s relying on you to get to shelter.
I don’t actually plan to switch it on at all especially since they tend to eat batteries. However I will be using Lithium/Iron sulphide cells (Energizer e2) that are meant to last about 7 times longer than alkaline cells according to the manufactures but seem to last a good three times longer according to reviews I’ve read.