Sorry for this outage and for the delayed response - the data stream changed while I was on holiday. I've just published an updated version to Google Play which should work its way through Google's servers in the next couple of hours. Please let me know if you still have any problems after installing the update.
I use Tide Prediction, which uses tidal harmonic constants derived from the Proudman Oceanographic Laboratory observations. These match closely (but not exactly) to the Admiralty predictions but don't require a connection to the internet to refresh and you can check for any point in time (instead of only 7 days ahead)