You’re seeing numerous “bottoms” in shallow water with a very hard bottom. This is an echo since you are using “high CHIRP frequency. The bug or issue that Humminbird is struggling with is the digital depth readout in scenarios like you posted. Your particular helix appears to be reading the correct depth and functioning correctly.
If you switch the sonar frequency to 83khz or decrease the sonar sensitivity what happens? My guess is that the double or triple bottom issue disappears.
The issue arises when the sonar unit is not able to differentiate between the numerous “bottoms” that the sonar return is showing. So in the first image you posted, the unit would be reading 15-20’ of depth when you’re really in 5’ of water.
Based off the sonar readings shown in each photo, the first picture has a significantly harder bottom than the second photo. Notice the red vs. yellow coloration of the bottom? Red is going to be your strongest sonar returns (hard bottom in this case) and as the colors change to orange, yellow, green then blue the sonar returns are getting progressively weaker.
He’s still very active on “another forum” posting pretty much daily on Humminbird related topics. Much of what I’ve learned in regards to Humminbird is straight from the horses mouth, and I’ve been doing my best to share some of that here. I’ve still got plenty to learn myself though, Wayne is a fantastic resource for all things sonar, especially Humminbird.
I made a bit of a mistake in my original post, the bug/issue isn’t specific to the Helix 10 CHIRP MEGA SI GPS G2N, it’s been reported across the whole line of G2 Helix MEGA units as well as the G1 Solix MEGA units.
The issue however, is not the units showing numerous bottoms like posted in the photo above, but rather the unit not being able to decipher which one of those “bottoms” is real- the digital depth readout will jump around between all 3 echos and show 5ft, 10ft, and 15ft of depth for the same location.
I read yesterday that Solix received a recent firmware update that supposedly addresses the issue, but still nothing on the Helix units as far as I can tell. The biggest concern with this bug is when using AutoChart live - if you’re not careful you might end up drawing a map with sharp depth contours that don’t exist..