For App Developers

The SailTimer API is available free on iOS and Android.  It displays battery power and signal strength to help the user to make the wireless connection.  The API does not display the wind speed or direction though;  that is where your app comes in.  The API is like a mini-app, with a very minimal interface.  It is intended to run quietly in the background, so that the user can view wind data in your app.  It gives your app some amazing capabilities:

1. Connects the wireless SailTimer Wind Instrument™ to your app.  You don’t have to learn how to parse the Bluetooth 4 packets, or have to work out a lot of calculations from magnetic to true wind direction, and apparent to true wind.  The API receives the Bluetooth data and reassembles it into NMEA 0183 text for you.  The API sends Apparent Wind Speed and Direction to your app.  It  also uses Location Services (the GPS) in the mobile device to calculate magnetic declination in the user’s location worldwide, and to convert from Apparent to True for the MWD sentence in NMEA 0183 format.  The Android version of the API also sends the MWV sentence for wind angle.  Full details are provided in the README.txt file that comes with the sample code.

2. Chart overlay from, showing live wind conditions and GPS tracks being crowdsourced worldwide.  Replays of events such as races and GPS tracks from a sailing trip can also be replayed in the cloud overlay.  All of your app users can contribute, whether they have a wireless Wind Instrument or not.

3. Optimal Tacks and Tacking Time to Destination (TTD ®).  The main tactical problem in sailing is choosing the best balance between tacking distance and speed for sailing upwind.  Until the patented SailTimer™ tacking results were developed in 2005-2006, it was not easy to get polar plots and optimal tacks.  These are available in the  SailTimer app for iOS, and are now also available to use for free in other apps.  Now with the SailTimer API, your app can have polar plot learning and display the optimal tacks to the next waypoint, including the heading, time and distance on each tack.

Android and iOS

For iOS app developers, the “SailTimerClient” is a working reference app which receives data from the API and displays it in a similar fashion. Data is sent from the API to your app on a port number using UDP.

For Android apps, the SailTimer API on Android shares data via broadcasted Intents (not via a UDP or TCP/IP port). Source code for a sample app is available that receives and un-encrypts the data from the API for display.

On both platforms, there is also a simulation that generates sample data for testing as if a Wind Instrument was connected.

We can also provide promotion for participating apps.  Please email for details on how to connect.

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