Navionics Help


SonarChart™ processing

SonarChart is produced starting from the Nautical Chart and other regional or local sources which might offer additional data. Navionics surveys supply information as well. We then validate and integrate sonar logs recorded by end users. This data is compiled from both plotter and mobile devices, adjusting for tide correction and filtering out “bad” data. 
Navionics generates a new SonarChart every day. After a user submits sonar logs for processing, the updated SonarChart will normally be available after about one week, with some exceptions. For example, processing may take from three up to eight weeks when sonar logs are submitted for an uncharted area, because a coastline correction is typically required and Navionics will first source new coastline information for the area.
It is technically not possible to process sonar logs if one of the following problems exist:
  • Latitude and Longitude is missing.
  • Depth data missing, incorrect or inconsistent with pre-existing data.
  • Missing time stamp. Since July 2014, a software update for Humminbird ONIX and ION units removed the time stamp information on the logs recorded in the Humminbird native DAT format. To avoid this issue, we recommend saving the logs in GPX format.
  • Sonar logs were recorded in a proprietary format not yet supported by the SonarChart process.
  • Sonar logs were recorded in an area where sonar logging is restricted at sea like Sweden, Norway, Finland, China and Hong Kong (see coverage).
In each case listed above, the sonar logs will be stored in the event that they can be used in the future and, if so, you will be notified.
For best sonar log recording, we suggest you keep your speed under 6 knots, although maximum logging speed may vary depending on which device you are using; perform a grid pattern where the distance between tracks is no more than 50 meters /150 feet; and save about every 30 minutes to reduce any risk of loss.
SonarChart is available for every customer to download to their Navionics+, Platinum+, and HotMaps Platinum plotter cards through our Daily Updates service, included free for one year with any of our plotter cards and is renewable after one year. On mobile, with an active Navionics+ subscription, enjoy the new SonarChart just by tapping Menu>Update All and selecting SonarChart using the carto selector icon. SonarChart can also be viewed online using the Navionics Chart Viewer. SonarChart coverage is available for the same regions as Platinum+ and HotMaps Platinum. We are continuously expanding coverage, so even if your area is not yet covered, recording and submitting sonar logs ensures that your favorite places will be included when coverage becomes available, so check back often.

We hope you enjoy the many benefits this extraordinary chart layer can provide to your time on the water. The more data Navionics receives, the higher the quality of SonarChart. You will certainly make a difference, especially if you were the first to pass over an uncharted area or one with recent changes. With many people contributing a little, even with a single sonar log, the Navionics Community  greatly benefits.

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