Lymington Tides?

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alant

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Online tide times, show a daily varying progression.
eg from the 5th to the 12th this month, they are as follows (HW time shown)-

1013 + 43mins = 1056
1056 + 46mins = 1142
1142 + 3h17mins = 1459
1459 + 47mins = 1546
1546 + 42mins = 1628
1628 + 33mins = 1705
1705 + 32mins = 1737

Why the difference of 3h17m from HW 7th to HW 8th?
The other days seem as expected.
 
I believe there are two peaks at high water for lymington. During springs range, the first peak is highest. During neaps, the second peak is highest. I expect you are seeing the changeover between the two.
 
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alant said:
Online tide times, show a daily varying progression.
eg from the 5th to the 12th this month, they are as follows (HW time shown)-

1013 + 43mins = 1056
1056 + 46mins = 1142
1142 + 3h17mins = 1459
1459 + 47mins = 1546
1546 + 42mins = 1628
1628 + 33mins = 1705
1705 + 32mins = 1737

Why the difference of 3h17m from HW 7th to HW 8th?
The other days seem as expected.
Click to expand...

Its due to the way the double high water is interpreted

On the 5th 6th and 7th the HW time is the time of the first HW

from the 8th onwards its the time of the 2nd HW

It was all explained recently
 
Exactly for passage planning. Unless you are drying out actual time of high water is relatively unimportant. However when you get to Poole the difference between neaps and springs high waters, both timing and height do have more relevance.
 
alant said:
Online tide times, show a daily varying progression.
eg from the 5th to the 12th this month, they are as follows (HW time shown)-

1013 + 43mins = 1056
1056 + 46mins = 1142
1142 + 3h17mins = 1459
1459 + 47mins = 1546
1546 + 42mins = 1628
1628 + 33mins = 1705
1705 + 32mins = 1737

Why the difference of 3h17m from HW 7th to HW 8th?
The other days seem as expected.
Click to expand...

Checked with HM.
Their published information for the same period, shows HW times as follows (+1hr for BST)
5th 0912
6th 0953
7th 1037
8th 1126
9th 1219
10th 1317
11th 1417
12th 1522

Thus, the online tide times are incorrect & the 3hr17min difference has nothing to do with peculiarities of spring tide HW & is an error.
Just shows how reliable the internet is.
 
alant said:
Checked with HM.
Their published information for the same period, shows HW times as follows (+1hr for BST)
5th 0912
6th 0953
7th 1037
8th 1126
9th 1219
10th 1317
11th 1417
12th 1522

Thus, the online tide times are incorrect & the 3hr17min difference has nothing to do with peculiarities of spring tide HW & is an error.
Just shows how reliable the internet is.
Click to expand...

Nope. I'm with the explanation given by VicS. He even went to the trouble of showing it to you by those arrows on the Easytide graph.

Now, different sources for tidal forecasts use different models and make different assumptions. With something like Lymington tides (or most of the Solent for that matter, plus Poole) there is no "right" or "wrong" for high water. Just different ways of expressing them.

Without knowing the source of the HM's data it is difficult to say, but it could simply be midway between low waters. That is probably "good enough".

It is what you are doing with the info that matters. There is a long stand at HW and it isn't instantaneous - so a single time, accurate to a minute, is pretty nonsensical.
 
Angele said:
Nope. I'm with the explanation given by VicS. He even went to the trouble of showing it to you by those arrows on the Easytide graph.

Now, different sources for tidal forecasts use different models and make different assumptions. With something like Lymington tides (or most of the Solent for that matter, plus Poole) there is no "right" or "wrong" for high water. Just different ways of expressing them.

Without knowing the source of the HM's data it is difficult to say, but it could simply be midway between low waters. That is probably "good enough".

It is what you are doing with the info that matters. There is a long stand at HW and it isn't instantaneous - so a single time, accurate to a minute, is pretty nonsensical.
Click to expand...

With a difference of 3 hours?
Rubbish!
 
alant said:
With a difference of 3 hours?
Rubbish!
Click to expand...

Not sure you are grasping what is going on here. Take today for example there is a stand from the first high water to the second of around 3 hours and the height difference between the first and second is approx 15cm. The two highs are roughly equal either side of the mid point between the lows.

So Angele is right - there is little difference between them (from a height point of view) although the strength and direction of the stream may vary in that 3 hour period.

There is nothing out of the ordinary about what is going on here, just a feature of the tides in this part of the world, as VicS shows with the extracts from Easytide.
 
Tranona said:
Not sure you are grasping what is going on here. Take today for example there is a stand from the first high water to the second of around 3 hours and the height difference between the first and second is approx 15cm. The two highs are roughly equal either side of the mid point between the lows.

So Angele is right - there is little difference between them (from a height point of view) although the strength and direction of the stream may vary in that 3 hour period.

There is nothing out of the ordinary about what is going on here, just a feature of the tides in this part of the world, as VicS shows with the extracts from Easytide.
Click to expand...

Tell that to the HM & Whitelink.
 
alant said:
Tell that to the HM & Whitelink.
Click to expand...

They are just choosing the first HW rather than the second in the list you quoted earlier. Just making different assumptions about what they consider HW. In fact as the tidal curves show there is a further rise after that time, so it is not the highest part of the cycle.

Really don't see what point you are trying to make.

Pretty sure Wightlink are well aware of the tidal curves.

Thought it was pretty common knowledge that that HW times are imprecise in the Solent (and west to Poole) and that tidal curves and streams are much more useful for navigation.
 
Tranona said:
They are just choosing the first HW rather than the second in the list you quoted earlier. Just making different assumptions about what they consider HW. In fact as the tidal curves show there is a further rise after that time, so it is not the highest part of the cycle.

Really don't see what point you are trying to make.

Pretty sure Wightlink are well aware of the tidal curves.

Thought it was pretty common knowledge that that HW times are imprecise in the Solent (and west to Poole) and that tidal curves and streams are much more useful for navigation.
Click to expand...

Well, the next LW time was 1723, so if the HM details are used, the difference is 5h57min, which is normal.
Using the online HW time of 1429, the difference is 2h24min, which would have resulted in a torrent of water leaving Lymington & never experienced.
Even the discharge after the double high in Southampton isnt that fierce.
 
Having used the scrubbing berths at Lymington i can confirm that going on at the top of the flood results in a long wait some hours with little variation of depth then a rapid fall allowing a quick scrub then a rapid rise. most of the day appears to be with in 300 mm of high water!
 
Ok, Alant.

Instead of worrying about differences in HW times of an hour or three, how do those two different sources compare at LW?

I only have a tidal curve for Lymington based around LW (the one in Reeds), and for tidal streams I use Portsmouth tides for the whole of the Solent. So, time of HW at Lymington is pretty irrelevant to me (and probably 90+% of other sailors in the Solent).

Now, if different sources of tide times were giving times of LW at Lymington that varied by an hour or more, then I would be concerned. So, how do they shape up?
 
alant said:
Well, the next LW time was 1723, so if the HM details are used, the difference is 5h57min, which is normal.
Using the online HW time of 1429, the difference is 2h24min, which would have resulted in a torrent of water leaving Lymington & never experienced.
Even the discharge after the double high in Southampton isnt that fierce.
Click to expand...


But this is exactly what happens in Lymington. Here are today's and tomorrow's tide (GMT) with the difference between HW and LW times. These are from the UK Hydrographic Office:

11-May HW 03:35
11-May LW 07:17 03:42
11-May HW 16:05 08:48
11-May LW 19:44 03:39
12-May HW 04:00 08:16
12-May LW 08:11 04:11
12-May HW 16:37 08:26
12-May LW 20:45 04:08

As you can see the ebb is significantly shorter than the flood. This is due to the fact, as has been mentioned above, that there are 2 HW and the tables only show one. HW is unreliable (as all RYA theory teaches :)). LW is what you should be basing your tidal calcs on.

Edit: Looking at the EasyTides predictions a bit more. The interesting thing is that Southampton is defined with 2 HWs in the tables but for some reason they don't do this for Lymington. I can see where the confusion comes from and have no idea why Lymington isn't shown with the same.
 
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RalphyM said:
Edit: Looking at the EasyTides predictions a bit more. The interesting thing is that Southampton is defined with 2 HWs in the tables but for some reason they don't do this for Lymington. I can see where the confusion comes from and have no idea why Lymington isn't shown with the same.
Click to expand...

Easytide has only just recently starting doing this for Southampton and Portsmouth and a number of secondary ports in the Solent. Interestingly, the list includes Yarmouth and Hurst, but not Lymington.

See here: http://www.admiralty.co.uk/Admiralty...r%20stands.pdf

Maybe they will get round to doing it for Lymington in due course.
 
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