There are a tonne of tools out there to navigate your way through to an intended destination, by car (or moped, bike and other options), on the road. In fact, tools such as Waze are incredibly detailed with live information on potential road blockages or other issues.
But what happens if you hire a boat or are a boating novice and you need to get to a destination you've never navigated? Or you need to get the boat to a quay which is far in-shore and you're not quite sure how to get there. There are plenty of obstacles and other issues in the way, plus you have to compete with the tide, weather and other boats.
OpenCPN is a tool you can use to navigate rivers and parts of the sea to get yourself to a destination. You can download and load the latest mapping information, but herein lies the first issue. It's not live and up-to-date information, but details pre-recorded and intended to help. Once you load your map, you can take advantage of collision detection, tidal-based route planning and weather updates (with a separate plugin).
The big downside is, this is a desktop application. There is a paid Android version available, but to navigate you'll need to take your laptop on the boat. You could simply choose your route and possible issues and print off the information - at least you have a route and fairly up-to-date warnings. But it sort of defeats the object of live navigation with alarms and updates along the route.
Powerful tool for boat navigation, but you need to download maps for updates.