How we fixed GPS timestamp handling, duplicate event prevention, and wind data accuracy.
Accurate GPS data is essential for sailing trip logging. In the latest update to mySailing (v1.6.0+305), we’ve made significant improvements to how the application processes NMEA0183 data from your GPS receiver. These fixes address timing issues, prevent duplicate events, and improve data accuracy—all designed to give you more reliable sailing records.
What Changed?
1. GPS Timestamps Now Drive Event Timing (The Big One)
The Problem:
Previously, mySailing used your device’s internal timer to decide when to record location events. This created a timing mismatch when testing with NMEA data playback—events would fire at the wrong intervals compared to the actual GPS timestamps in your data stream.The Fix:
We now use GPS timestamps directly from the NMEA sentences to determine event intervals. This means location events are recorded based on GPS time, not phone time.
NMEA connection settings in mySailing. The improved timestamp handling works seamlessly in the background.
Why It Matters:
- ✅ Location events now respect your configured interval (default: 60 seconds) based on actual GPS time
- ✅ Testing with fast data replay works correctly
- ✅ Better consistency between your device time and GPS data
Technical Detail: Location events are now emitted using the same NMEA-time-driven logic as all other telemetry events (wind speed, COG, SOG, etc.).
2. Fixed “Stuck” Events on Connection Problems
The Problem:
All telemetry event types (Beaufort, RPM, wind direction, log state, COG, SOG, VAR) had a “busy flag” that could leak under certain conditions. If no active trip was available when an event was about to be recorded, the flag wouldn’t reset, causing events to get stuck and stop being recorded.
The Fix:
We now properly reset the busy flag whenever a trip isn’t available, allowing events to resume normally.
Why It Matters:
- ✅ Events won’t get stuck after starting without an active trip
- ✅ More reliable event recording throughout your session
- ✅ Better behavior during NMEA connection issues
3. True Wind Only—No More Conflicting Wind Data
The Problem:
Your GPS receiver may send two types of wind data:
- True Wind (WIMWD) — wind relative to the water/Earth
- Relative Wind (WIMWV) — wind relative to your boat’s heading
mySailing was processing both, which could create conflicting wind speed and direction values depending on which sentence arrived last.
The Fix:
We’ve disabled processing of relative wind (WIMWV) sentences. The application now uses only true wind data (WIMWD), which is more useful for sailing analysis and weather logging. But in near future we will allow to register both types of wind values.
Why It Matters:
- ✅ No more conflicting wind values in your trip log
- ✅ Clearer wind data for analysis and export
- ✅ The code for relative wind is preserved, so we can re-enable it in the future if needed
4. Event Throttling Now Works as Intended
The Problem:
The logic that decides whether to record an event had a subtle bug. It wasn’t correctly handling the “either-or” condition: record if either the value changes significantly or enough time has elapsed.
The Fix:
Fixed the throttling logic to properly respect both threshold conditions:
- Event recorded if value changes beyond the configured threshold, OR
- Event recorded if sufficient time has elapsed since the last event (whichever comes first)
Why It Matters:
- ✅ Slower events (like wind direction) are still captured at regular intervals
- ✅ Fast-changing values don’t get over-sampled
- ✅ Your trip logs have complete event coverage without excessive duplication
Who Benefits From These Fixes?
NMEA Device Users
If you use a marine GPS receiver or NMEA multiplexer connected to your device, these fixes ensure more accurate and reliable event recording. Your sailing logs will have timestamps that align with actual GPS time, not phone time.
Fast Data Replay (Testing & Analysis)
If you use mySailing with test NMEA files for software testing or post-trip analysis, the GPS-timestamp-driven timing now works correctly even during fast replay. Test scenarios that previously failed now pass.
Multi-Sensor Setups
If your boat has multiple sensors (wind, depth, speed, heading) connected via NMEA, this update provides cleaner, more consistent data with fewer conflicts. Wind data is now unified around a single, reliable source.
Quick Comparison: Before & After
| Aspect | Before Fix | After Fix |
|---|---|---|
| Event Timing | Device timer (phone clock) | GPS timestamp (actual data) ✅ |
| Stuck Events | Possible after connection issues | Cleared automatically ✅ |
| Wind Data | May show conflicting values | Single consistent source (true wind) ✅ |
| Event Throttling | Partial (not both conditions) | Full (either threshold OR time) ✅ |
| Test Replay Accuracy | Incorrect intervals | Correct intervals ✅ |
How to Update
These improvements are included in mySailing v1.6.0 and later:
- iOS: Available on the App Store
- Android: Available on Google Play
Simply update your app to get these improvements. NMEA data handling will work more reliably from the moment you launch the updated version.
What’s Next?
We’re continuing to improve GPS and NMEA support. Future updates may include:
- Support for additional NMEA sentence types
- Configurable wind data preferences
- Enhanced event filtering options
- Real-time diagnostic logs for NMEA troubleshooting
Questions or Issues?
If you experience any issues with NMEA data recording after updating, please reach out to our support team with:
- Your NMEA device model
- A sample of your trip log (or NMEA test file)
- Description of the issue
We’re here to help! Your feedback helps us continue improving mySailing.
Happy sailing! Update mySailing today and enjoy more reliable GPS data tracking on your next trip.
