UKH

I'm participating in a race next week where we can use our mobile phones for navigation.

Does anyone know if there is a way of locking my phone so that it only shows the map application? Ideally the map would track my position automatically at a pre-specified zoom level.

I don't want it running any other apps.

One of the problems I find with my phone, is that as I sweat or if it's raining, the touch-screen is useless, so I want to avoid having to use the touch screen.

Set it running with your mapping app and then disable touch screen.

https://www.makeuseof.com/tag/disable-touchscreen-input-android-iphone/

If it's an iPhone I think they have something called Guided access mode which will lock the screen and all inputs by triple pressing the home key. I only know this from on the iPad if you give it to a toddler to watch something you can do this to stop them turning it off etc.. 

Might work for your needs too if you can do it on the iPhone if you have one.

Thanks. I didn’t know that. That’s useful. 
 

https://support.apple.com/en-gb/HT202612

I have the Anquet OMN app on my phone. You can download all the tiles, then turn off wifi, bluetooth and data and the battery will last longer. Using a waterproof pouch usually solves the sweat problem, the cheap plastic seems to be less sensitive so reacting to what you want more often. 

I should have specified it's an android phone, but I'll try the suggestions tonight, thanks!

This almost worked out for me. The disable touchscreen app couldn't be set if I pinned the map app to the screen.

Instead I used an app called "Touch Protector" where I can enable/disable touch screen using the physical buttons (e.g. I selected double clicking the volume buttons).
So, I pin my map app, which means it is always on, and then I disable the touch screen. I can still put the phone in standby mode, and when I press the on button it comes straight back up with the map centered around my position. 
I'll put the phone in to airplane mode with GPS enabled, and I'm good to go. A GPS only mapping device.