I use this app every day as a professional navigator. Very good for quick azimuths. iOS update created some color problems. I emailed them, and the problems are fixed with a new version very quickly.

I've been impressed with this app since I figured out how to use it. Really all I'm doing with it is using it as a calculator for sights I've taken and it's a labor saver. I use a drum sextant and enjoy it. This calculator makes the solution faster to arrive at. That said, I still do it longhand because electronics can, and often will fail. Of course, this is why we still use sextants and windvanes :p