Tripmeter distances and corrections
The roadbook and tripmeter need to describe distance from the same reference. Total distance is cumulative from the relevant start or reset. Partial distance is the interval between the printed references; check the roadbook’s convention before resetting anything.
| Reference | Total |
|---|---|
| Previous row | 12.40 km |
| Current trip | 12.90 km |
| Next row | 13.15 km |
Calculate the next interval
One row is at 12.40 km and the next is at 13.15 km. The interval is 13.15 − 12.40 = 0.75 km, or 750 metres. If the tripmeter is aligned and reads 12.90 km, about 0.25 km remains to the next row.
Correct only at a confirmed feature
You positively identify the junction printed at 12.40 km, but your total trip reads 12.55 km. It is 0.15 km ahead of the roadbook. Adjust the displayed total down by 0.15 km to 12.40 km, using your instrument’s procedure. That aligns this known point; it does not prove the instrument is calibrated for the rest of the route.
Do not correct away uncertainty
If you are unsure which junction you reached, changing the tripmeter to match a guessed row can hide the error. Stop somewhere safe, compare the route features and work from your last confirmed position. Know which control changes total distance and which resets the partial counter.
Check your understanding
At a confirmed 8.20 km landmark your trip reads 8.05 km. Which correction aligns the total?
Show the answer
Increase the displayed total by 0.15 km to 8.20 km. The tripmeter is behind the roadbook at that point. Do not reset it to zero unless the roadbook explicitly establishes a new zero there.
These are simplified training examples. For an event, follow its roadbook, briefing and equipment instructions. See the field guide and its sources for the wider navigation context.