Good day! I have two questions. HDS 9 GEN3 (software version 4.5 application 56.1.142) does not see the card in AT5 format? The main map of Navionics.
Second question. Why is the isobath map showing a depth of 10 meters deeper than the actual values recorded in the logs? thank

Do you have your unit set to show "Lowrance" maps?
Can you give more information on the depth issue please - maybe a screen shot of the project would be useful as well. There may be some bad data points in the recording that are affecting the generated map. If so, these need to be deleted in the track view, either individually or by using the depth filters.

Good day! On the first question. I am sending a screenshot of the track image in the editing mode and viewing the echo sounder records. All track points are 10m deeper than an echo sounder recording. In all projects and all tracks. Therefore, isobaths are denoted by incorrect depths. On the second issue. Alas, Lawrence does not offer an HDS echo sounder. I am sending a screenshot from the echo sounder, in which in the mode of viewing the file list it can be seen that the device does not even display the name of the file in AT5 format. Below is a file with a name that I downloaded from the Internet, but it also does not appear in the device. I would appreciate a solution to this problem.

when exporting from ReefMaster make sure to export to a specific folder on your computer.
Then on the root of your SD card make sure you have a folder named Map0 (if not just make it).
Put your own map folder inside Map0. this way your unit will show it with your customized map name.

Good day! Unfortunately, the cards exported from Reef Master and placed in the Meps 0 folder in the root directory of the CD card do not appear in the Map Sources field in the settings of my Lowrance device. At the same time, Waypoints created in Reef Master were successfully imported into the device. I tried all the options for exporting the map to At5 format, but not one of the options appeared in the "Map Sources". I also tried loading other users' ready-made maps in At5 format, but they also are not displayed by Lowrance. Tell me in which direction should I move to remove this problem? Maybe this is not the correct work of Lawrence? Thanks!

Читайте русфишинг и всё будет впорядке. Вы плохо читали инструкцию.

The "Maps0" folder is not a requirement for HDS Gen 3. It's a requirement for older versions of the OS.

An At5 without a description string will appear on the Lowrance chart selection option on that chart plotter. I'd recommend using a custom description string because the blend with base map behavior is not consistent on all devices.