Currents uses data about coastal tidal currents and displays this data as an overlay on Google Maps.
The coastal data is created by the CO-OPS group at NOAA. It includes more than 2700 stations on the Atlantic, Gulf, and Pacific coasts. This data is available on the NOAA web site, tidesandcurrents.noaa.gov. The data for 2012 is at tidesandcurrents.noaa.gov/currents12. At this time, data in Currents is available for the year 2012.
Each station is represented on the map by either a dot or one of five differently sized arrows. The dot indicates either a weak and variable current or a current under 0.1kts. The five arrows represent speeds, in increasing order, of < 0.5kts, < 1.0kts, < 2.0kts, < 3.0kts, and > 3.0kts.
Occasionally, you will see this image for a station. This indicates that the NOAA data for that station for the given time and date appeared to be incomplete or inaccurate. Instead of trying to interpret what the data should be, it has simply been flagged as invalid. As an example, the Tampa Bay area has stretches of days when the data doesn't appear accurate.
The data is not pulled directly from the NOAA web site. To provide good performance, it was neccesary to retrieve all of the NOAA data for 2012, rearrange it and compress it. The compressed files reside on the yoyana.com site. Each time you change the day, a new file is downloaded. You'll notice a slight delay when changing the day. The last 30 files are locally cached on your phone. I encourage you to spend some time on the NOAA site and with Currents to corroborate that the data agrees.
When you tap on any of the stations, you'll see a pop-up window similar to the screen shot. It provides information on the Current state (pun intended) for that station at the selected time. We call each maximum Flood/Ebb and time of Slack an 'event'. You're given data on the prior event, an estimate of the speed at the selected time, and data on the next two events. Keep in mind that the NOAA data are predictions. The speed provided at the selected time is an interpolated estimate using the prior and next events. To dismiss the pop-up window, tap on any of the text in the window.
Currents is available in the Android Marketplace. Search for 'yoyana' or 'currents' to find the application. You can also get a copy at yoyana.com/Currents/Currents.apk or scan the barcode with your phone. Feedback on program usability, accuracy, and performance is greatly appreciated.
Icons and graphics for this App were created by Shannon Wheeler, who is attending James Madison University.
