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Post Options Post Options   Quote OultonBen Quote  Post ReplyReply Direct Link To This Post Topic: Start Time Errors
    Posted: 22 Oct 13 at 10:34am
With lots of handicap racing and to apply accuracy to timings, the Club has run off Radio-Controlled Clocks with one in the usual Start/Finish-Box, and one on the Committee Boat in case that is to be used (not always).
After some years, discovering a mis-match in times on the clocks, two new ones were purchased.
Immediately there was <1-sec of difference between the two, but within human reaction-time, so not a problem.

After a short while some timings became suspect; at home during the week clocks were monitored against each other, a standard wrist-watch and computer-time:
Sure enough, one older clock jumped -2 seconds (at about ~17:00), then next forenoon was showing +10 seconds, so a +12 sec jump;
one of the newer clocks jumped -59 seconds overnight, then seemed gradually to gain +2 sec (between 18:00 and 23:00), returning to 0 by the following forenoon.

National Physical Laboratories were contacted;   there is little confidence that R-C clocks will show continuous correct time.  The problem is that they can jump, and this significant jump is unpredictable (maybe during a race, before or after, or at night .... ).
Therefore for race-control it is probably safer to use a standard, non-radio clock.

post-script:  At an Open Meeting the competitors all recognised a start-time error of ~36 sec;  the Race-Officer was unaware of any error, save that competitors were strangely unprepared for the start.
The reason for mis-match was un-attributable, but a Redress hearing abandoned the race.


Edited by OultonBen - 22 Oct 13 at 10:35am
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Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 13 at 10:45am
Don't you just count down from 5?

I suppose it might matter where in yaht races you are told tht your start is at 11.00 (never done these, so not sure how they work) but otherwise, I'm not sure how it purtains to race starts?
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 13 at 10:48am
If you are recording finishes by clock time rather than stopwatch, and the clock time gets adjusted by a minute in the middle of the race then its a bit unfortunate. Moral, use stopwatch setting!
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Post Options Post Options   Quote OultonBen Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 13 at 11:10am
Originally posted by Rupert

Don't you just count down from 5? ......
Hi Rupert,
That'd mean counting-down just about every second, since IF the clock were going to jump at some indeterminate time, it might do so at say, 3min:28sec, becoming 3min:21sec, and you might not have spotted that ???
Often, very reasonable count-downs hit 'key' points like every 30-sec, and during the last 30-sec every 5-sec, and during the last 5-sec every sec.   Problem is if there's a time-jump between key-points, or if the key points are too widely separated.


Edited by OultonBen - 22 Oct 13 at 12:03pm
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Post Options Post Options   Quote OultonBen Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 13 at 12:03pm
Originally posted by JimC

If you are recording finishes by clock time rather than stopwatch, and the clock time gets adjusted by a minute in the middle of the race then its a bit unfortunate. Moral, use stopwatch setting!
Hi JimC,
Notion of occasionally having a Cttee-boat, starting several races, with finishing conducted at a fixed line from a normal-use race-control office.
The idea of having 2 Reliable Clocks one afloat & one ashore seemed conveniently to obviate the need to use one stopwatch and coordinate times across the radio (before, during, after a starting sequence; nightmare!);  what was unexpected is that the Reliability of Radio-Controlled clocks is very questionable.

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Post Options Post Options   Quote Presuming Ed Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 13 at 12:44pm
Originally posted by OultonBen

National Physical Laboratories were contacted;   there is little confidence that R-C clocks will show continuous correct time.  The problem is that they can jump, and this significant jump is unpredictable (maybe during a race, before or after, or at night .... ).
Therefore for race-control it is probably safer to use a standard, non-radio clock.
 
(Excuse me one second. The colours and variable size fonts have given me a headache.
 
 
 
OK, that's better.)
 
Very interesting. I didn't know that - most ROs I know use RC clocks.
I note with interest that the ISAF policies are to base timings on GPS time. But there are problems with that. http://gpsinformation.net/main/gpstime.htm
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Post Options Post Options   Quote OultonBen Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 13 at 1:56pm
Originally posted by Presuming Ed

.....Therefore for race-control it is probably safer to use a standard, non-radio clock.
 
(Excuse me one second. The colours and variable size fonts have given me a headache.
.... OK, that's better.)
 
Very interesting. I didn't know that - most ROs I know use RC clocks.
I note with interest that the ISAF policies are to base timings on GPS time. But there are problems with that. http://gpsinformation.net/main/gpstime.htm
Hi again Presumptious,
Sorry if you've got a headache (He-He!) ..... clearly not enough time spent accustoming to rose-tinted specs or something ?

EXACTLY the Point;  this particular Club had, in their innocence, assumed through the marketing that RC Clocks only appeared on this Earth very shortly after the Big-Bang, or at least after Sliced-Bread !
What they do not tell you is that RC clocks have a mind of their own and can skip at will, usually by only a few seconds, but I now have evidence of full minutes [NPL.co.uk can confirm this].

Since SailBoat races are usually subject to human reaction for gauging start-time, finish-time or sighting a finish-line and transferring that to a timing, it is probably perfectly adequate within the envelope of controllable errors to use a wind-up grandfather clock (I bet some Cowes support boat somewhere has one of these on-board); ludicrous to expect help from a timing device to the nearest hundredth, or thousandth of a second, but what is controllable is Not to use a device that might be skippy; do Not use RC Clocks for timing particularly handicap races.
Yep, I recognise the GPS time issues also.
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Post Options Post Options   Quote Lukepiewalker Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 13 at 3:42pm
Surely you would expect them to jump, as and when they update to the radio signal? Depends on how often they do that I suppose.
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Post Options Post Options   Quote OultonBen Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 13 at 4:10pm
Originally posted by Lukepiewalker

Surely you would expect them to jump, as and when they update to the radio signal? Depends on how often they do that I suppose.
Hi Lukepiewalker,
That's what you might have "Expected", in all innocence as said previously.
The spec. says that they'll correct automatically and if they don't receive a signal then they'll search at 02:00, or 03:00, or 04:00;  all our clocks are saying that they've got a good signal yet ...... ?
However that's not reflected in reality; (I did this 3-years ago but now again), over the last 3-days I've monitored clocks and assumed Google time to be my Reference, in which case one RC clock has +1sec during yesterday evening, then corrected itself overnight, and another RC clock has -59sec overnight from Sunday, then +60sec on overnight correction (but when ?), and during today has actually +1sec further and very gradually over 7-hours.
Last week a clock showed -10sec, then during late afternoon +2sec in front of Commodore's eyes;  his reaction was excitedly to ring-around saying that he wouldn't have believed it if he hadn't seen it with his own eyes !

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Post Options Post Options   Quote Jon711 Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 13 at 5:17pm
Hi Ben, I'm assuming that this is at your inland club.... When they first appeared there, and I was RO for some races during regatta week, I had my suspicions, but just assumed it was me being stupid.

With that in mind (tongue in cheek), can I claim redress for the 3rd M/C race 7 years ago? Those timings were definitly wrong!!

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