SailTimer API - WMM‪™‬ 4+

SailTimer Inc.

Designed for iPad

    • 2.0 • 1 Rating
    • Free



An API is a digital toolkit; this one handles the Bluetooth 4 LE connection to the SailTimer Wind Instrument™ ( This app is only for the WMM Edition.

The WMM Wind Instrument uses the sophisticated new NOAA-British Geological Survey geomagnetic model for compass declination, since magnetic north has been moving around faster than usual in recent years. No matter where or when you use your Wind Instrument, it will have the same high degree of accuracy that it did in the factory. Completely new firmware in the Wind Instrument also allows you to get over-the-air updates with this app, for new electronics functions that may become available in future.

After scanning for your Wind Instrument, you can rename it with an identifier like your boat name. No-one else can see this, but it ensures that you are connecting to your own Wind Instrument in a marina. Once yours is connected, any others will not be displayed.

You can let this app run in the background. It hands off the wind data to other sailing, racing or chartplotting apps for display, even if the iPhone/iPad screen is turned off to conserve power. It converts wind data from magnetic to true north, from Apparent to True, and from wind direction to angle. The app converts all of this to the NMEA 0183 standard marine electronics format for other apps. Streaming data is shown in green text as the wireless data arrives from the Wind Instrument to show you when the connection is made. There is a Pause/Play button in the upper right of the green text.

The API tries to reconnect automatically if the Bluetooth signal is lost, or the next time you come back to the boat. In the upper right corner there is also a circular Dis/Connect button. That is handy when leaving the boat, or also if you want to save power in the iOS device and in the Wind Instrument when not in use. The Wind Instrument uses about 44% less power when Bluetooth is not connected. Similarly, your iPad/iPhone uses less power when the GPS (Location Services) and Bluetooth are shut off with the Disconnect button. Continued use of GPS running in the background can dramatically decrease battery life. This app may use your location even when it isn’t open, which can decrease device battery life.

Logging in gives you the option to display wind conditions at your location online. That is handy if you want to share your location with others for safety. And if you want to check wind conditions and temperature at your boat from home. You can Register the first time in the API or at Then you can simply log in to the API, and you won’t have to log out or log in again.

In the Settings menu, there is a Smoothing option for the rare time that the wind is jumping around and needs damping. There is also an advanced function for Compass Quadrant Fine-Tuning. This is also rarely needed, but gives you the ability to fine-tune the precise degrees for North, East, South and West where the Wind Instrument is mounted on your boat (e.g. because of magnetic deviation from nearby objects).

The Settings menu also lets you set Wind Instrument speeds at 1, 3, 5, 10 or 20 times per second (Hz). Wind gauges move more smoothly with faster transmissions, but numerical displays may change too fast. You may want fast transmissions for an autopilot, or may prefer to conserve battery power in your Wind Instrument with fewer transmissions.

New simulator for testing True Wind Direction (TWD) and True Wind Speed (TWS). Long-tap on the wind cup icon to start. Double-tap on the wind cup icon to stop. Allows you to enter boat speed and heading and wind speed and heading, and check TWD and TWS in the first line of green text (MWD in NMEA0183 format).

*If you are getting the app and like this wireless technology, please help out other sailors by letting them know, with a quick rating on this version while you’re here.

What’s New

Version 2.1

• Smoothing is now over number of transmissions not number of seconds, since transmissions can be multiple times per second. Increase smoothing if a wind display is too jumpy (especially at faster transmission rates) because of mast vibration, boat pitching etc.
• Improvements to the geometry behind the conversion to True Wind Speed (TWS) after extensive testing with Apparent Wind Speed (AWS) and Angle (AWA).
• For more accuracy and ease of use, Apparent Wind Direction (AWD) is displayed for True Wind Direction (TWD) if GPS speed less than 2 knots. AWD and TWD should be the same then. This prevents TWD from fluctuating because of GPS resolution when you are not moving.

Ratings and Reviews

2.0 out of 5
1 Rating

1 Rating

App Privacy

The developer, SailTimer Inc., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Location

Privacy practices may vary, for example, based on the features you use or your age. Learn More

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