The Richta Rally Checkpoint Clock is an application designed as a timing device for use at checkpoints during Time-Speed-Distance road rallys. It can also be used as a time reference for Class B or "Seat of the Pants" rally classes.
When the "Split" button is pressed the clock records the time of the split in a scrollable log area at the bottom of the display. Log entries can be reviewed by scrolling the screen and individual log entries may be deleted. The clock can be dynamically changed to record in seconds or hundredths of a minute (decimal minutes). A facility is provided to adjust the time of day clock independently of the devices clock so that the app can be synchronized to an external time reference without changing the device's clock.
The accuracy of the clock over time, sometimes called drift, depends on the accuracy of the underlying hardware. I have had very good results using this on my Galaxy Tab. You should check your device before using this app on an event.