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Jon711 View Drop Down
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Posts: 465 		Post Options Post Options   Quote Jon711 Quote  Post ReplyReply Direct Link To This Post Topic: Start Time Errors
    Posted: 22 Oct 13 at 7:14pm
Oh, I meant to add, the new boat may suit your style of sailing, looking forward to seeing you in it.

Just done a quick google, you would not need to link the PIC's on the VHF... Apparently there are (or were) quartz timed PIC's, so all you would need to do is coordinate the times at the start of each day, and then all races would start and finish on club time.

My first doubts about RC clocks came about, when wearing a GPS watch (A bit OTT for the water, but a fun gadget), and noticed differences, initially, I put it down to GPS errors, but they just seemed to big..... Now we know! (According to my GPS, it did give me a peak speed of 35 knots in the Blaze, in a force 3!)

We just need to research programming PIC's.... Although, is this a sledgehammer to crack a nut? But if the skills are in the club, it may be a bit easier than it sounds. Certainly, with the multiple starts in regatta week, I would have thought that the timings needed to be good, as to use the Cruisers for example, seconds can make all the difference, and regatta week scores, go towards the Sabrina Trophy points - having won that one on Vagabond, I know how much it means to cruiser sailors...

And, congratulations, on being a Grandad! Will that make you the only grandad in your new class?

Jon

Edited by Jon711 - 22 Oct 13 at 7:22pm
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Jon711 View Drop Down
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Posts: 465 		Post Options Post Options   Quote Jon711 Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 13 at 6:37pm
Yes, I heard about the long call, and your defection to yet another class!!

Just a thought, as the club is using standard marine VHF's would it not be possible, to with a PIC chip linked to the radio, to coordinate the times between the CB and the race box. The times do not actually need to be BST or GMT just coordinated. I would guess that Scott may know how to program PIC's and link them in, if not, I (or Scott) may have to do some research....

Not totally sure that it is a feasible option, but worth investigating....

BTW, I think I can make an educated guess as to the class involved, from some of the Facebook posts of the competitors and parents....
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Posts: 49 		Post Options Post Options   Quote OultonBen Quote  Post ReplyReply Direct Link To This Post Posted: 22 Oct 13 at 6:20pm
Hi Jon,

Yes, there's been p-l-e-n-t-y of strange mixed fleet handicap timings (Couple of times per season, maybe? Not enough to really worry the majority, but significant enough.) and I've been banging-on about this for over 4-years now Wacko;  I personally have very little confidence in Radio-Control clocks and now have my own empirical evidence Geek ...... heck last week in exasperation Mr Commodore himself took clocks home;  later one evening he could hardly contain himself in seeing-with-his-own-eyes a shift of +12sec happen, from a mismatch of -2seconds between two of the RC-clocks; he was quickly onto the phone Shocked.


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Posts: 465 		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!!

jon
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Posts: 49 		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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Posts: 1341 		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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Posts: 49 		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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Posts: 641 		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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Posts: 49 		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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Posts: 49 		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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