# Could someone explain the operation of this wristwatch for me?
**URL:** https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815
**Category:** Factual Questions
**Created:** [April 10, 2008, 10:50pm UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815 "2008-04-10T22:50:26Z")
**Posts on this page:** 17
**Page:** 1
### Author:  [@Argent\_Towers](https://boards.straightdope.com/u/Argent_Towers)
#### Post date: [April 10, 2008, 10:50pm UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/1 "2008-04-10T22:50:26Z")
[Here](http://cgi.ebay.com/NEW-Corum-Admirals-Cup-44-Tides-18k-Rose-Gold-28-600_W0QQitemZ360040480869QQihZ023QQcategoryZ31387QQrdZ1QQssPageNameZWD1VQQ_trksidZp1638.m118.l1247QQcmdZViewItem) is a very nice Corum Admiral’s Cup wristwatch on eBay. It has three subdials and is described by that auction as having :
> [@](#):
>
> …state of the tide over a period of 24 hours, water heights by factors of 25 (20-45, 95-120), times of high and low tide, strength of currents…
How does that watch know how high the water is and how strong the current? How does it physically figure that out?
I really want to know.
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### Author:  [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)
#### Post date: [April 10, 2008, 10:55pm UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/2 "2008-04-10T22:55:50Z")
[QUOTE=Argent Towers]
[Here](http://cgi.ebay.com/NEW-Corum-Admirals-Cup-44-Tides-18k-Rose-Gold-28-600_W0QQitemZ360040480869QQihZ023QQcategoryZ31387QQrdZ1QQssPageNameZWD1VQQ_trksidZp1638.m118.l1247QQcmdZViewItem) is a very nice Corum Admiral’s Cup wristwatch on eBay. It has three subdials and is described by that auction as having :
How does that watch know how high the water is and how strong the current? How does it physically figure that out?
I really want to know.
[/QUOTE]
For $18,000 you could have a Rolex and pay a guy to put a stick in the water for you…
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### Author:  [@Argent\_Towers](https://boards.straightdope.com/u/Argent_Towers)
#### Post date: [April 10, 2008, 11:17pm UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/3 "2008-04-10T23:17:31Z")
Bah, everyone has a Rolex. At some point I’d really like to get myself one of the less extravagant Admiral’s Cup watches like [this one.](http://cgi.ebay.com/CORUM-ADMIRALS-CUP-982-530-20-V785-AN32-List-3-895_W0QQitemZ290218150408QQihZ019QQcategoryZ31387QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247) I really dig the signal flag numerals.
But does anyone know how the tide watch works?
---
### Author:  [@Darryl\_Lict](https://boards.straightdope.com/u/Darryl_Lict)
#### Post date: [April 11, 2008, 12:34am UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/4 "2008-04-11T00:34:12Z")
In 2001 I bought a tide level watch manufactured by Nike. It was, of course, a computer. It had various geographical locations that you would enter. I actually bought it because when walking on the beach around here, you can only make it around certain points at low tide. I actually used it once when gong on a tide pool exploring beach walk in some Asian country that I can’t remember.
From what I know, tides depend on local geography and position on the globe. I understand that a large portion of it is derived empirically. I don’t really see how a mechanical watch can perform this task with any degree of accuracy.
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### Author:  [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)
#### Post date: [April 11, 2008, 2:14am UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/5 "2008-04-11T02:14:04Z")
[QUOTE=Darryl Lict]
I don’t really see how a mechanical watch can perform this task with any degree of accuracy.
[/QUOTE]
I don’t think it’s a purely mechanical watch- probably autoquartz. (self-winding, but doesn’t use a mechanical movement).
None of the sellers I found provide any useful information about the movement, though.
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### Author:  [@Starving\_Artist](https://boards.straightdope.com/u/Starving_Artist)
#### Post date: [April 11, 2008, 2:49am UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/6 "2008-04-11T02:49:42Z")
[QUOTE=Argent Towers]
Bah, everyone has a Rolex. At some point I’d really like to get myself one of the less extravagant Admiral’s Cup watches like [this one.](http://cgi.ebay.com/CORUM-ADMIRALS-CUP-982-530-20-V785-AN32-List-3-895_W0QQitemZ290218150408QQihZ019QQcategoryZ31387QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247) I really dig the signal flag numerals.
But does anyone know how the tide watch works?
[/QUOTE]
Have you thought about emailing the seller and asking him, or perhaps checking with the watchmaker or one of its retail outlets?
If you’re smart enough to have earned (or at least not blown 😃 ) the dough necessary for a watch like that, finding out how it works shouldn’t be all that daunting.
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### Author:  [@Starving\_Artist](https://boards.straightdope.com/u/Starving_Artist)
#### Post date: [April 11, 2008, 3:02am UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/7 "2008-04-11T03:02:21Z")
Another thing you might want to consider if you’re going to be using it in the water. That watch is only rated to 5 ATM\* for water resistance. That means it’s only good for showering or swimming but not for diving. Frankly, if I were going to spend that kind of money on a wristwatch, particularly one associated with being on the water, I’d want it to be more water resistant than that.
ETA: You may also get specific instructions on the watch’s operation [here](http://www.corum.ch/dev_0206/index.html) but it is a pdf file so I didn’t open it.
\*As per Corum’s website [here](http://www.corum.ch/dev_0206/index.html).
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### Author:  [@astro](https://boards.straightdope.com/u/astro)
#### Post date: [April 11, 2008, 5:31am UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/8 "2008-04-11T05:31:12Z")
[Here](http://www.lussori.com/corum-admirals-cup-tides-44-watches.html)
It’s apparently related to some aspect of a moon phase reference…
[Answer should pop up here shortly.](http://forums.timezone.com/index.php?t=msg&th=1047102&start=0&rid=18486#)
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### Author:  [@astro](https://boards.straightdope.com/u/astro)
#### Post date: [April 11, 2008, 5:42am UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/9 "2008-04-11T05:42:54Z")
In looking at [the instructions](http://www.corum.ch/dev_0206/pdf/en_actides48.pdf) for the very similar “Tides 48” it’s apparently a rough estimate based on lunar phase and strength of the last tides.
> [@](#):
>
> Setting the tide functions
> Three items of preliminary information are needed to set the tide functions:
> The time and day’s date
> The time of the previous high tide
> The date of the previous full or new moon
>
> Setting the lunar cycle in phase (small dial at o’clock):
> The example below is based on a full moon. The same operation can be carried out by analogy from the new moon. Count the number of days since the date of the previous moon (example: from the 13th (date of the full moon) to the 20th of August: 7 days). Press corrector C successively until the hand on the small dial at 12 o’clock faces the full moon symbol. Press corrector C as many times as twice the number of days since the last full moon (example: 7 days x 2 = 14 pressures).
>
> Reading the information:
> The hand indicates the phase of the moon and the amplitude of the tide simultaneously. Positioned below the full moon symbol, it indicates a period of particularly high tides (coefficients between 95 and 120). As the days go by, the hand moves towards the last quarter (moon crescent symbol, located on the right-hand side of the small dial) and shows a period of relatively low tides coefficients between 20 and 45). A period of high tides then follows during the new moon (black moon symbol, at the bottom of the small dial) and of neap tides during the first quarter (moon crescent symbol located on the left hand side of the small dial). All these phases together last for approximately 29 days.
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### Author:  [@Argent\_Towers](https://boards.straightdope.com/u/Argent_Towers)
#### Post date: [April 11, 2008, 7:11am UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/10 "2008-04-11T07:11:29Z")
Thank you all very much for the explanations.
**Starving Artist** , where on the Corum website does it specify the water resistance of the watch? I can’t find it.
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### Author:  [@astro](https://boards.straightdope.com/u/astro)
#### Post date: [April 11, 2008, 7:23am UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/11 "2008-04-11T07:23:52Z")
[QUOTE=astro]
[Here](http://www.lussori.com/corum-admirals-cup-tides-44-watches.html)
It’s apparently related to some aspect of a moon phase reference..
[Answer should pop up here shortly.]([http://forums.timezone.com/index.php?t=msg&th=104710](http://forums.timezone.com/index.php?t=msg&th=104710)
2&start=0&rid=18486#)
[/QUOTE]
reply
> [@](#):
>
> They don’t. They fake it.
>
> They use the calculation that tides follow a 25 hour cycle. they do in about half the world, but this is utterly useless in the other half, where tides don’t follow much of any predictable cycle at all. One of these places is the West Coast of the USA.
>
> Tides may follow the moon, but they are also extremely influenced by underwater geography and ocean currents. Influenced, in fact, to the point what a watch of this sort becomes totally useless.
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### Author:  [@Argent\_Towers](https://boards.straightdope.com/u/Argent_Towers)
#### Post date: [April 11, 2008, 7:47am UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/12 "2008-04-11T07:47:45Z")
Well fuck it then, I’m not going to get bamboozled by those Swiss charlatans. How do they get away with such a lie?
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### Author:  [@bbs2k](https://boards.straightdope.com/u/bbs2k)
#### Post date: [April 11, 2008, 8:30am UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/13 "2008-04-11T08:30:42Z")
**astro** , you missed a very good opportunity to post “QUOTE=Somewhere Else”.
Hah!
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [April 11, 2008, 8:58am UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/14 "2008-04-11T08:58:33Z")
[QUOTE=astro]
reply
> [@](#):
>
> They don’t. They fake it.
>
> They use the calculation that tides follow a 25 hour cycle. they do in about half the world, but this is utterly useless in the other half, where tides don’t follow much of any predictable cycle at all. One of these places is the West Coast of the USA.
>
> Tides may follow the moon, but they are also extremely influenced by underwater geography and ocean currents. Influenced, in fact, to the point what a watch of this sort becomes totally useless.
[/quote]
That reply sounds like BS to me. Sure, tides don’t resemble a simple sine wave every(or any)where, and I’m sure there are all kinds of confounding factors, but ‘tides don’t follow much of any predictable cycle at all’ _has_ to be bullshit.
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### Author:  [@Starving\_Artist](https://boards.straightdope.com/u/Starving_Artist)
#### Post date: [April 11, 2008, 4:13pm UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/15 "2008-04-11T16:13:34Z")
[QUOTE=Argent Towers]
Thank you all very much for the explanations.
**Starving Artist** , where on the Corum website does it specify the water resistance of the watch? I can’t find it.
[/QUOTE]
Sorry about that. I copied the link while at the water resistance explanation and thought that’s where it would go when clicked upon. There are a few steps required to get there:
1 Click “Continue” at bottom of “Warning” dialog to clear it out.
2 Then click “Press Releases” at bottom of page.
3 Click “Water Resistance” at upper right of page.
4 Scroll message for full explanation
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### Author:  [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)
#### Post date: [April 11, 2008, 8:45pm UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/16 "2008-04-11T20:45:40Z")
[QUOTE=Argent Towers]
Well fuck it then, I’m not going to get bamboozled by those Swiss charlatans. How do they get away with such a lie?
[/QUOTE]
Switzerland is a landlocked country.
---
### Author:  [@Arnold\_Winkelried](https://boards.straightdope.com/u/Arnold_Winkelried)
#### Post date: [April 11, 2008, 9:28pm UTC](https://boards.straightdope.com/t/could-someone-explain-the-operation-of-this-wristwatch-for-me/444815/17 "2008-04-11T21:28:01Z")
I might try to e-mail the company. I don’t see how the watch can predict tides with any accuracy unless there is a way to indicate to the watch what your latitude and longitude currently is.