Onwards and upwards. Got the basic display settings showing what you want? You can turn on the backlight, display your distance moved per stroke (as advocated by British Rowing – the most important speed measurement to track).
Now onto accuracy and calibration: The HC allows you to use either a coxmate micro impeller or the NK impeller. You can set the display to accommodate this. Because the micro-impeller spins faster than the NK you'll get hugely fast or slow speed readings if you fail to set this up.
And to calibrate the HC manually (assuming you've done two pieces on flat water over a marked distance and have recorded the offset error from the device reading against the actual disatnce).