Offline navigation is essential for any outdoor traveling. Bad or even no data signal in mountainous, rural or otherwise deserted areas makes online navigation useless. Locus Map in default settings offers navigation with the help of implemented online services. Firstly it is GraphHopper online router followed by YOURS.
If you want offline navigation, you have to install cooperating routing app BRouter, available at Google Play Store >>. Locus Map identifies it in the system and adds it automatically to the portfolio of available routers.
BRouter remains set as default also for route drawing in the Route planner
Although BRouter user interface looks quite simple, the app offers quite a lot of various settings, creating custom navigation profiles etc. A rich source of info and tips is this wiki-blog >>. BRouter provides also a web app, enabling route planning on a big PC screen and consequent export to GPX file and then to Locus Map.