searching for a clock

[Jools_of_Top_Cat]

I have identified I need a decent accurate clock at my helm. I have decided upon my criteria.

1. Digital, with two readout LCD screens so I can have UTC and local together, or see point 2
2. A countdown timer with alarm, and a normal timer too, to show at same time as time see point 1
3. A normal clock alarm, decently audible, no digital watch type tinny squeek.
4. Backlit
5. low power consumption
6. Weatherproof, though it will be sheltered in my centre cockpit it may still be rained on.
7. Reasonable price, I would like to pay less than £40 is that wishing too much

Desirable

1. Temp readout
2. White and able to fit to bulkhead
3. Memories, i.e. Press a button to fix time for later insertion in log.
4. Ergonomic controls, don’t wish to have to refer to manual every time I use it

Has anyone anything similar, if my price is way out please advise anyway. Is such a thing available? Or will I have to build one from Maplins endless kits.

Any advice appreciated.


<hr width=100% size=1><font color=blue> Julian </font color=blue>

<A target="_blank" HREF=http://www.topcatsail.co.uk>Homepage</A>

 

[escape]

I don't use one myself but have sailed with others who use relativly cheap LCD wrist watches taped close to the helm.
Most have all the functions you mention, just dosn't look too pleasing and you have to check the compass!!!

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[peterb]

I haven't yet seen a wrist watch with a memory for the time. I've been looking for some years, because of its obvious use in astro-navigation. I've wondered whether something like the lap timer on a stop watch could be used; push a button and the time reading is held, push again and the display catches up again.

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[snowleopard]

spent ages searching for a clock with a digital display including seconds to use as a chronometer. found one in the end but it loses half a minute a week. don't fancy your chances but if you strike lucky let us know!

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[vyv_cox]

It has long been a source of amazement to me that digital instrumentation, while showing every conceivable piece of information such as water temperature, true wind speed and direction, etc. etc., doesn't include a timer/clock. Yet at the same time we can buy telephones, pens, key rings, GPS, binoculars, gas cookers etc. etc. that do. All I want is an alarm that goes off every hour to remind me to fill in the log, just like the simplest Timex that is too quiet to hear when inside waterproofs and typical sailing clothes.

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[Twister_Ken]

The good old days

My Stowe log offers a countdown timer which can be set to any interval betweem 0 and 59 minutes. That's at least 15 year old technology.

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[qsiv]

Most GPS receivers include a clock display, which should be accurate to about 2 seconds in 1000 years, as it is updated by the atomic clock in the satelite.

I accept they dont have memory functions for time, however.

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[Dyflin]

I have the same problem. Wanted a watch for time when doing celestial navigation and taking gyro compass bearings. Find I have to reset the watch every time I go on the bridge

If anybody has an accurate digital wristwatch, please let us know!

~Dyflin



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[Twister_Ken]

Old Timex Ironman

Mine used to be good to a second a month. Then it was borrowed by an offspring and never seen again.

And a professional skipper I used to know used an Ironman in prefence to the ship's chronometer on many Med/Carib (and vice-versa) x-ings in the days before GPS.

No idea if the current ones are as good, but in theory any digital quartz timepiece should be accurate as long as the chip in them counts to 32,768.

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[vyv_cox]

Re: The good old days

My B&G Hornet does the same. But that's not the same as the hourly two bleeps produced by a Timex or similar. Who wants to reset a countdown timer every hour?

Finding the time isn't the problem We have countless means of doing that, two brass clocks, one with alarm, two wrist watches, GPS, organiser, two car radios with digital time displays, Eberspacher programmer, calculator, where does it end? All we want is two audible beeps every hour, although we'd settle for one.

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[BrendanS]

Couldn't find an exact fit, but these were interesting:
http://www.weatherconnection.com/product.asp?itmky=682170
available in uk for £35

http://www.wirelessalarm.com/NU868.htm
very different to what you asked for, but might suit some people.




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[BrendanS]

Yes, but they don't run to UTC time, they run at GPS time, which is different.

I think they are currently about 13 seconds out of sync, so they can never be accurate to 2 seconds in 1000 years. OK for general use though.

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[qsiv]

I honestly doubt that a standing offset of 13 seconds (I thought we had actually had 22 leap seconds since 1972) would be critical to the average sailing boat. What is perhaps more relevant is the time difference between two observations. In any event it is so much more stable than 'normal' timepieces that I suspect it is rather academic. For my part I'm afraid I dont even record the time to the nearest second in my logged entries - maybe a future Government edict will require us to record data to such accuracy, when preparing our statutory passage plans!

In fact my figures are wrong - caesium based atomic clocks are inherently accurate to better than 1 second in 5 million years.

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[Twister_Ken]

Watches

As you say, no end of watches will do this, no bother (mostly when you're sitting through the pianissimo movement in a concert). What's needed is as way of amplifying the watch's bleep. How about mounting it on a sounding board, rather than a wrist swaddled in oilskin storm cuffs?

A rectangular frame a few cms in each dimension, with a plastic membrane stretched tightly across. Watch (or watches for dual time) held to frame by strap mountings, and just touching the membrane. Would it work? If so, whole thing could be made neat and tidy suitable for mounting under the sprayhood.

I might experiment with this at the weekend. There are enough half dead digital watches in various drawers at home.

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[qsiv]

Actually I'm puzzled now.

As far as I can establish the GPS atomic clocks (up 4 on each sattelite) are periodically synced to UTC(USNO). The GPS time tick itself is 17 seconds or so adrift from UTC, however this divergence is transmitted from the satellites, and GPS receivers which display UTC apply (or SHOULD apply) this delta so that what they display as UTC should be correct. I've just compared mine with an internet time server, and it appears to be correct to within 1 second - so my guess is that Garmin, at least, are using the time difference data. The time transmitted by the satellites can be as much as +/- 340 nanoseconds adrift (thats the SA allowance, but is normally +/- 9 nanoseconds) - and your receiver wont be aware of this.

UTC(USNO) is itself synced to UTC(BIPM) (the international standard for UTC) every 14 days. The stated accuracy of the synchronzation is ...

UTC(USNO) has been kept within 26 nanoseconds of UTC(BIPM) during the past year through frequency steering of our Master Clocks to our extrapolation of UTC(BIPM).

Over the past 5 days the maximum divergence has been +/- 5 nanoseconds - thats good enough for me!

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[tome]

GPS v UTC

Bit of confusion here Brendan!

GPS time is continuous since midnight on Jan 5 1980 whereas UTC is adjusted occasionally with an integer number of leap seconds to fit the 'real world'. The offset between the two times is tranmsitted as part of the Navigation data in the C/A code received by all GPS receivers, which is why they all (to the best of my knowledge) convert GPS time to UTC and operate in true UTC.

Time is the 4th parameter (after lat,lon,height) which the receiver determines - this is why you need at least 4 sats for a 3-D fix. Theoretically, the absolute time error will be less than 100 nano-seconds but in practise the output and display of time is a low-prioroty processor task in the GPS set so some latency, typically 0.25 secs, can be expected.

Professional GPS receivers have a pulsed output every second where the pulse is accurate to within 200 nanosecs.

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[qsiv]

Re: The good old days

Autohelms watchkeeping alarm comes close (but I cant remember if you can set the interval as far apart as hourly)

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[BrendanS]

Re: GPS v UTC

oops! better go do some more reading this evening

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[tome]

Re: GPS v UTC

There's a great little book from Trimble called 'GPS - A Guide to the Next Utility' which I used to hand out to students on quite advanced nav courses. You can read it in about 30 mins and it's a great intro to what is quite a complex subject. I've only 1 tatty copy left, but there's a tutorial at trimbles site:

<A target="_blank" HREF=http://www.trimble.com/gps/index.html>http://www.trimble.com/gps/index.html</A>

GPS is the nuts and bolts of what I do in our (oil & gas survey) business so I'm surrounded by it daily and in danger of becoming a boring old anorak!

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[DeeGee]

I am surprised by your posting, someone has mislead you.

GPS is UTC, as a Stratum 1 time-service it is within 150nanosecs of theoretical UTC.

[sorry, posted this before seeing the other previous.....]

<hr width=100% size=1>Black Sugar - the sweetest of all<P ID="edit"><FONT SIZE=-1>Edited by DeeGee on 10/04/2003 17:40 (server time).</FONT></P>