When SonarChart™ Live was first introduced it rendered contouring without any interaction with underlying chart data. This means that the data coming directly from your wireless sonar transducer was taken at face value and used to draw contours reflecting actual depths recorded under current conditions no matter what level of tide or water level adjustment you may have been experiencing at that time. When you returned to the same location at a different time, or on a different day, the previously recorded contours shown in SonarChart Live would start to change due to the influence of new data collected under new conditions. This may have yielded unexpected elevation changes.
With iOS Version 8.2 & Android version 6.0 a feature was introduced that will allow you to enable automatic tide adjustment (Marine) or manual water level adjustment (inland lakes & rivers). Essentially, SonarChart Live will subtract the tide height (or manual water level offset) in real time from the data recorded from your wireless sonar transducer. The contours drawn will reflect low tide normalized depths using a nearby tide station verified by you.How this works:
When a wireless sonar device is detected the SonarChart Live recording will start. The app will then ask you to select the type of waterway in which you are traveling: Marine or Inland. If Marine is chosen, the app will then show you available nearby tide stations from which to make your selection. Depending on your location, for example the proximity to an inlet, the closest tide station may not always be the most appropriate tide station.
Should you wish to avoid correction of any kind, simply tap the X to close the window and no adjustment will be applied to your SonarChart Live view.
While underway and using SonarChart Live, contours and depth area color shading will reflect the values subtracting the current tide condition reflected in the chosen tide station. For regions with a high tidal exchange it is possible that you may be recording in an area at high tide that would otherwise be dry at low tide. The below example is taken in New England where tide exchange can be in excess of 11 ft. The yellow track line indicates the path of the boat at high tide. The red arrows indicate an area where the boat has passed into an area where the depth below the transducer is 11 ft or less. Subtracting the 11 ft tide change, the depth value is zero, so the SonarChart Live has no contours to draw and is masked. As depth below the transducer increases beyond the 11ft tide change, SonarChart Live begins to draw contouring to reflect the normalized, low tide condition.
Depth information collected by using SonarChart Live is shared with Navionics to create SonarChart, our HD bathymetry layer available for both plotter and mobile charts. The depth information comes to Navionics without tide correction or manual water level offset. Navionics applies Water Level offset or Tide Adjustment to the raw data during normal processing procedures before SonarChart updates are issued.