Capt Fathom, nope, it's just that the marine software has a dead reckoning mode. It is therefore important to know which mode you are in as confusion can prove fatal.
The voice alerts are very useful since I'm often sailing single handed with a lot of stuff to do.
Both in the air and on the water, I work on the old saw: "never pass up an opportunity to fix your position." GPS can sometimes do strange things and when that happens a pencil mark and a time on a paper chart are your best friend.
I've had that experience integrating my marine system with its Laptop, flux gate compass, gyro, GPS, integrated log and wind instruments and Autopilot. I can assure you that it is very disorienting when the various bits start disagreeing with each other, and the safest thing to do is turn everything off, get out the chart, and play with the toys when safely at anchor.
To put it another way "A man with one watch knows what time it is. A man with Two is never quite sure."
Anyway, hopefully at the end of the month I'll give the software and iPad a Two week workout with some outback touring. I'll be able to compare Ozrunways with the aircrafts TSO'd GPS and moving map system.