I flatline a lot. To get the depth from trolling data I do two steps. First, let out the amount of line from the data. Second, I put on a small clip on weight and slowly let out more line untill the clip just kisses the surface of the water. Example 60 ft for depth plus 40 ft to get the line down from the rod tip to the water surface. 100 ft total. Make adjustments as needed for boat speed.

Good Luck!