To mark a point of interest, you can place a cross-hair type marker on the sonar view. Click one of the Reference Cursor buttons. Choose where you want to place the cursor, then click the left mouse button to place it. The range and bearing of the cursor’s position — relative to the Sonar Head — is shown in the bottom-left corner of the view.
When you place both cursor 1 and cursor 2 on the sonar display, the cursor range and bearing — relative to the Sonar Head—
will be displayed. “Delta” shows the range and bearing from cursor 1 to cursor 2.