There are three versions of the app available in the Apple Appstore.
In the full version , for the iPad the current position of the ship is constantly shown on the map and the map will be automatically adjusted to the position.
    Install Full version

The Lite Version for iPad and iPphone is free and works the first 30 days exactly the same as the full version.
After that the vessel will not be shown anymore, all other functions stay the same!
    Install Lite version

There is also a version designed only for the iPhone. It has the same features as the full version for iPad but is cheaper.
    Install iPhone Version