You can use a mount for smartphone. Charging is easy to solve - just use a big enough powerbank + full phone battery when heading out and you should be good for

You can use a mount for smartphone. Charging is easy to solve - just use a big enough powerbank + full phone battery when heading out and you should be good for at least a full day of non stop navigation + screen on. I agree on small screen... but then again, you can use a tablet instead of a phone. According to my experience (off road motorbiking including a rally with weather going from really hot to bad downpours and everything in between) using a cheap (120€) rugged phone works just fine. There can be some lag sometimes (100+ km/h on a motorbike is way faster than what most boats can manage though) but in this case you rely on Mark 1 Eyeball and spatial awareness anyway. During rally we were required to carry an old school map of the area so if your GPS device failed you could find your way back to bivouac. I carried a spare phone, because it's cheap enough anyway. Can't speak for nautical charts but for general navigation I guess OSMAnd should work just fine. I'd still recommend against going out without basic navigation experience, relying on a smartphone only.