NMEA and Logook App
General information to the NMEA interface
the NMEA (or National Marine Electronics Association) interface is implemented and usable with the Logbook App, either with UPD or TCP. However the configuration menu is hidden as the feature to access NMEA data is still in beta state and not public by default. If you would like to use it, please get in touch with me to ask how to reveal the NMEA configuration menu. Please let me also know what kind of hardware you are using to get your NMEA data into your WiFi.
Keep in mind
Apple does not allow apps to access TCP or UPD data streams directly in background. Background means the app is not on screen. So Logbook App will loose the NMEA connectivity once you lock your iPhone or iPad, or bring another app on screen. Therefore I prevent iOS from going to sleep once a NMEA connection is established.
Supported NMEA Sentences / Data
It plays no role which NMEA device is sending the sentence. So the first two letters after $ describe the device. Logbook App will consider all sentences independet to the sending device.
RMC RMC = Recommended Minimum Navigation Information
Is used to record SOG, COG and GPS position.
MWV MWV = Wind Speed and Angle
Is used to record wind direction and wind speed. Independent to the source data apparent or true, the wind data is converted to true wind.
VHW VHW = Water speed and heading
Is used to record CTS (Course to Steer / course through water) and VTW (Velocity Through Water). Furthermore the Current Drift and Current Set is also calculated based on the difference compared to the last received RMC Sentence which includes SOG and COG.
DPT DPT = Depth of Water
Is used to record Water depth, also if the current app release V2.33 has no possibility to show or adjust the data, it is already recorded in the device local database for later processing in an upcoming update release. Water depth gets calculated with the Offset before saved to database. The offset describes the difference betwen your sensor and the real water surface. This ensures the real water depth is logged and not just the depth below your keel.
MTW MTW = Mean Temperature of Water
Is used to record water temperature.
VLW VLW = Distance Traveled through Water
Is used to record Chip Log, without NMEA the Chip Log value is calculated by adding the distance to th last record to the value of the last record. With NMEA, nothing is calculated, but the value from NMEA is taken.
GGA GGA = Global Positioning System Fix Data
Is used to record GPS accuracy.