spitty me old china,
i didn't bother using a clipboard stopwatch for the IR. most transponders have an inbuild stopwatch thing and its found using that one much easier. get yourself a stopwatch anyway just in case, and i have a digital one. basically it has a one touch reset so when you're abeam the beacon you just blip the button and the whole things resets to zero.
good luck with your IR thingy next year. give me a bell some time to catch up. it's your inverness based buddy here
