Different apps, which unfortunately are not always working on both systems: The I-Phone and Android devices.
Free of charge: A map of the Frisian Lakes. inclusive: Bridge control, water depths etc. Search in Google play for: Vaarkaart Friese meren, or go to www.vaarkaartfriesemeren.nl
This app gives accurate information, not only about where you are, but also information from the latest Almanac. For € 3.99 per week.
With this app, you can not navigate very intensive, but you can determine to a certain waypoint. For € 3.99 a week.
At Navionics you can choose out of plenty of apps, but useful for the Netherlands is the Marine app: UK & Holland for €24,99. This provides detailed maps, intuitive operation and a large amount of additional information about for example currents and tides. You also have the possibility to enter waypoints with e.g. on water depth's.