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your car is necessary to ensure your on-time performance is
as good as it can be. You need to be sure your Odometer readings
are the same as the ones used by the plotters of the event.
This is done by calibrating your car’s odometer against
a fixed, standard distance. CARS has established standard
Calibration Runs in North, Central and South Trinidad for
use by the plotters and competitors of our rallies.
To calibrate your car, simply follow these steps:
1. Ensure your car’s tyre pressure is what it should
2. Align your car’s front tyres with the start line
of the Calibration Run.
3. Zero your car’s trip-meter if possible, or note
your current odometer reading.
4. Drive to the end of the Calibration Run (avoid overtaking).
5. Align your car’s front tyres with the finish line
the same way you did at the start.
6. Note the trip-meter reading, or subtract your start odometer
reading from your end reading
If your odometer reading is different from the Calibration
Distance, whether higher or lower, then your car is out of
calibration. Your car’s Calibration Factor is a constant
value, which when multiplied by the distance read off your
car’s odometer, will give the Corrected Distance.
7. Calibration Factor = Calibration Distance / Odometer
8. Corrected Distance = Odometer Reading * Calibration Factor
On a 10 km calibration run, your car’s trip-meter read
10.2 km. You enter a rally with an average speed of 20 kph.
After 10 km, you meet a checkpoint. What is the error in your
Elapsed Time if you ignore the calibration information?
* Timing Factor = 60 / 20 = 3 min per km (see Time Calculations)
* Wrong Elapsed Time = 10 * 3 = 30 min from start.
* Calibration Factor = 10 / 10.2 = 0.98
* Corrected Distance = 10 * 0.98 = 9.8 km
* Correct Elapsed Time = 9.8 * 3 = 29.4 min from start.
Since you round down to the minute, your correct Elapsed
Time would put you 1 minute late at the checkpoint and you
would continue running progressively later by 1 minute for
each 10 km rallied (a typical rally covers over 50 kms).
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