Tide Clocks

[Plan_B]

Hi Guys,

I've seen these clocks and watches advertised in all sorts of mags and never really taken any notice of them. Somebody asked me today, how do they work, are they accurate and are they worth the money? How do they know that the tide gets x amount later each time.

Has anyone had experience of these - and are they just gifts for mariners that have everything?


Dave D

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[Roberto]

I have a casio wristwatch showing tides: it stores the moon phase by itself, then I had to add a constant which depends on the particular location you want the tide to be predicted; obviously only the moon component of tides is considered so the difference between what the watch shows and the reality has a sort of cyclic error: sometimes a little in advance, sometimes a little late
Considering that tide height is shown by the watch in two hour steps, there is not much of an error: if it can be inaccurate in establishing slack water, it is almost always correct in indicating rising or falling water



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[ChrisE]

Suprisingly, they do work, I got one for Christmas.

They are plumbed for moon phase time and run on about a 25 hr day. You set them to your local HW and off they go. Mine is OK as a guide but because the lunar day is not constant throughout the year, I believe sometimes the times are up to an hour out. Also, it isn't very clever regarding the funny Solent tidal effects but over time, though, it seems close enough.

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[Capt_Marlinspike]

Work fairly well for most ports, not much use for the area from Selsey Bill to Poole of course due to the double HW.

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[Boathook]

I have had one of the clocks for quite a few years having purchased it in France. I don't rely on it but use it as a talking point. Being based at Christchurch I used to set it for low water which is more reliable than HW for the 'solent' area.

Must reset it again and possibly a new battery !!

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[GeorgeP]

Hi Dave.

I have one of these on my boat and they look nice. Not much use for tidal predictions though. The boat's in Poole, so HW and LW don't exactly follow the moon. Also, when you sail along the coast a little, then you need to reset them to the new port.

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[DavidofMersea]

You seem to be asking about two different products, watches and clocks, and people have talked about both, mainly watches.

I was given a tidal clock about two years ago. At first I could not see the point, it seemed like a one handed clock and something that just looked pretty, and did not tell you anything, but the obvious.

However, after a time I found it very useful to know, although it is not very accurate, at a glance whether the tide is rising or falling, and how far up or down the tide is. ....and it looks pretty

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[kindredspirit]

The tidal part of the clock works on a 24 hour 50 minute rotation system.

I find the tidal clock extremely useful for when say, tying up to a pier, and knowing the tidal range for that day in feet, I can instantly work out, with a glance at the clock, how much water I'll have under me at low water according to the twelfths rule.

When you move along the coast for a day, you can automatically allow in your mind, when you look at the clock, for the flood/ebb being an hour later/earlier whatever.

<hr width=100% size=1><A target="_blank" HREF=http://www.begleys.com/weather.htm>Useful links for Irish waters.</A>

 

[Plan_B]

Thanks to all you guys for responding. A very mixed bag of answers. Seems like most people like them and sort of use them, but don't rely on them too much. A sort of rough guide, but never a substitute for the tide tables.

Dave D

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