I bought the SPOT Gen3 a few weeks before hitting the AT in March 2016. The main impetus for this purchase was being able to stay in touch and let folks know my coordinates in case I couldn’t use my phone.
The SPOT GPS functions in a few different ways. The only thing I used it for was sending my exact GPS coordinates once a day, usually when I set up camp. Other folks on trail had it and left it turned on all the time to track their steps. That was a little too much sharing for me, so I only turned it on once a day. This saved the batteries, and I never needed to replace them. I also boosted the life by plugging it in and charging it whenever I got to a town for a zero day.
There are three main “messages” you are able to send via text or email to a list of people you’ve set up. The first is a generic message; I let people know I was OK, followed by coordinates that the recipients could click on and pull up a map of my exact location.
The second message option I reserved for a non-critical emergency. I let people know there wasn’t an emergency, but I need their help. For example, if I had lost my phone off a cliff in Vermont and then gotten giardia days from a good road, I could push that message, have it go to a different group of people, and get assistance. (They knew I might not be able to respond, and the SPOT doesn’t have texting ability, but they would know my location.) The third message is the (figurative) BIG RED BUTTON. It is a button, and it had a plastic flap over it, and you have to push it for 10 seconds before it works. (I also covered the flap with duct tape to add an extra step.) You want these extra steps, because if you hit this button, it calls the cavalry. We’re talking medivac helicopter, mountain rescue, ambulance, the whole nine yards. SPOT offers an additional insurance plan to cover these really expensive costs, should you need them.
I kept my SPOT secured in my left hip belt pocket. I figure my pack goes with me everywhere, and if I were to fall and be immobilized, I would likely still be able to move my arm and hand just a little bit to get to that pocket. People using the SPOT to track all their steps usually clipped them to the front of their packs with a carabiner, because the SPOT relies on a clear shot of the sky to work.
I was happy with the performance of the SPOT, and there were only two times on the entire AT that the canopy was too thick to get a good clear area to activate the SPOT.
If I were to purchase a GPS device again, I would prefer one that had texting (both receiving and sending on-the-fly custom messages), as well as emergency service capabilities.