Argos
Go to Argos,get a watch ( not necessarily digital-I find analogue easier for calculating ETA's) to look after time of day and a simple sports stopwatch for leg time.
A single digital watch can mean switching between time of day and stopwatch and it can be easy to accidentally zero the stopwatch.
Keep it simple-Nav can be a high workload and you don't want to be fiddling around with multi function timepieces.
Good luck
MM