Rock-hit detection

Trenchers occasionally meet something they can't go through — a buried rock, a hard pan, an old field tile, frost, or just very dense subsoil. The blade lifts above the design line because the implement physically can't drive any deeper. If Ditch Assist let that error keep growing, you would either burn out the trencher trying to force it down or run the rest of the line at the wrong depth.

Rock-hit detection watches for this and lifts the target so the rest of the run stays usable.

On by default — turn it off if a job false-triggers

Rock-hit detection is a Tiling-only feature, controlled by Settings → GRADING → Rock Hit Detection. The default is ON for tiling. If soft or stony ground creates false triggers on a job, turn it off for that run.

What triggers it

While auto-grading in Tiling with the setting on, the app watches GPS altitude in a sustained sample window. A rock hit fires when both of the following hold:

• The blade is pushed more than 2 inches above the design target at the current position (the trencher can't reach grade).
• The blade stays above that 2-inch gate for the full sustained sample window (not a single noisy reading).

A 5-second cooldown sits between fires so a sustained obstruction doesn't re-trigger the banner over and over.

What happens

When the detector fires:

1. A yellow Rock Hit — Design Adjusted banner appears at the top of the grade screen for 5 seconds.
2. A yellow SnackBar carries the same text in case the banner is missed.
3. A brief beep plays.
4. The app auto-nudges the target up by the current error amount — you don't need to tap Nudge yourself. The blade stops fighting the obstacle.

What to do

In most cases, nothing — keep trenching. The new target is at the shallower line and the chart shows the lift.

If you suspect the trigger was a false positive (you lifted the implement deliberately for a road crossing, or the blade bounced over a tree root), tap Hold before you reach the obstacle so the system pauses sending commands instead of treating the lift as a rock hit. Tap Release to resume normal grading after.

A gotcha worth knowing

If the bucket swings off the trench and dips deeper while passing over a previously-graded bin, that swing reading overwrites the stored value for that bin. This is the same overwrite behaviour the achieved-grade overlay uses everywhere — Rock Hit Detection inherits it. Unlikely in normal trencher cadence, but worth knowing if your chart suddenly shows a deeper-than-actual spot.

At the inlet end

Stop as normal. The applied nudge stays as part of the job; if you resume the job later, the lifted target is what the app remembers.