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racing times accuracy

hello all,
i have been checking the pics and vids from my london tri last saturday and just noticed that the time showing on the huge digital clock above the finish line the second i am crossing it has a discrepancy with my recorded time of 23-24secs (my recorded time is by that much longer)
does anybody know how this works? do they take the time that shows on your chip when they remove it from your ankle?
i am not in a position to be challenging any world records with this but 24 seconds are 24 seconds...!


  • ZacniciZacnici Posts: 1,385
    Your chip time should reflect the clock time as presumably you all started en masse at the sound of a klaxon etc. What can happen is that sometimes the chip does not register as it crosses the mat; it has happened to me at least twice where I did not hear the beep and brought it to the attention of the finish line official, in those cases they reverted to a backup timing system which was synchronised stopwatches and a master clock. In both cases I was also adrift by a few seconds as the time was taken at the point that I brought it to their attendtion, one of those instances was at the Nottingham tri last year I was subsequently placed behind a competitor that followed me over the finish line about 50 metres behind.

    It happens and in my case not disastrous but as you say 24 seconds is 24 seconds.
  • huwdhuwd Posts: 228
    Did the finish line clock show time-of-day when you crossed it? Is it possible that the start hooter was 24 seconds later than expected time of start?
  • sportevesporteve Posts: 141
    thank you for your respone zacnici,

    what you mention about the start raises another issue for me (pls forgive me, my first one so not very familiar with how it is all recorded...):

    how do they register your time at the swim start? is it if you start say at 12:00 o'clock they start all the chips at 12:00 or is there a sensor in the water that logs the exact moment you literally cross the start line?

    do you think i can dispute it with the organisers or is it too late?
  • sportevesporteve Posts: 141
    yes huwd,
    it was time of day...my wave was meant to start at 5:00 and i am seen at the vid crossing the finish line at 18:54:41-2 and my recorded time is: 01:55:07
    i am really bad at calculations number but if the hooter had gone later then i should have a shorter time not a longer one ...no? or am i getting this wrong
    as you can see by my above question i am not clear from which point they start timing you either...i started at the back of the pack too ...
  • ZacniciZacnici Posts: 1,385
    I also do 10K events (running) and if chipped there are 2 times, Gun time and Chip time. Gun=klaxon ie, loud noise everyone starts in a running event it is simple then to have a chip start time of when you cross the sensor at the start line.

    Obviously that doesn't happen with a triathlon so the master clock is manually synchronised with the klaxon, i.e. loud noise start button pressed - or countdown sequence initiated on master clock and starter given a 3-2-1 make loud noise.

    Now if the clock you are referring to is showing actual time as opposed to elapsed time then it has all the usefulness as a sun dial! Just because the off is scheduled for 17:00hrs doesn't mean that you actually set of at that time, the last event I did we were 32mins late! So I conclude that your chip time was probably right and ignore the big clock.
  • risris Posts: 1,002
    how fast does sound travel? 24secs could be how long it took the sound of the klaxon to reach the person pressing the button

    i'd agree with zacnici - the chip seems more reliable than the clock, they could have held you in the water for 20secs at the start and you'd never know.
  • ZacniciZacnici Posts: 1,385
    Approximately 330m/s at sea level (speed of sound) so klaxon would have had to be about 7.5Km away
  • sportevesporteve Posts: 141
    oh you boys you just make me stand here in awe....facing your scientific intelligence extraordinaire....

    in te meanwhile i will settle for my 523rd position trying to imagine what it could be like to be 519th....
  • ZacniciZacnici Posts: 1,385
    One does try to be of service - compliment gratefully accepted - don't get many these days.
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