Help with Poole tides please

yachtmilos

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17 Aug 2015
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A question of two halves here which we would really appreciate some help with.
1. Whilst sailing back from Portland we were looking at dropping anchor at Poole or Swanage. Looking at the tide tables from different sources we found they differed. It was the 8th August (neaps) so am guessing it is something related to it being neaps - if so could someone please explain clearly as to why this happens and which source of information to follow? I know that Poole Harbour tidal curve is based on the LW time anyway and there wasn't a great difference given for HW and LW heights, but still curious.

For example, Reeds gave times as (have converted to BST)
HW 0749
LW 1123
HW 2017
LW 0008

whereas others (e.g. Boatie App) gave (BST) - clearly LW times are the same (although BBC actually gave the second LW as 1524, which confused me even more!)
HW 0259
LW 1123
HW 1624
LW 0008

Similarly times for Swanage were different according to where we looked. We have checked them all again recently and they are now all showing the same information, but still curious about it all.

2. Also, we noticed on the Swanage page of the almanac, dashes were given in the tide table rather than times for HW and differences for Swanage (for secondary port calculations) and this was also the case for Poole entrance and pottery pier etc. Having not seen this before, why is this different and how do we calculate HW times?

Apologies if this is all very obvious and we have missed something - a bit new to all this and haven't come across this before. Any information to clarify would be very welcome. Thanks
 

Stemar

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No expert, but IIRC,there are two high waters in Poole Harbour, so which do you choose?. LW does have a meaningful time, so this is quoted.

Differences are pretty small - at neaps it can be just a few inches and is only about 1.5m even at springs, though that's quite enough to spoil your day if you get it wrong off the beaten track!

HTH
 

DJE

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Fareham
IIRC where there is double high water the quoted time in Reeds and Admiralty tables is the higher of the two. So we occasionally get sudden changes in HW time at Southampton when the predicted higher tide changes from first to second from one day to the next. I remember reading a pilot book for Poole years ago that said something like "almost unpredictable at neaps". There is a double high water in Poole so my guess is the two sources are using different high water peaks.

My rule of thumb for Poole is highish for 8 hours, falling for two hours before LW, and rising for two hours after LW. The range is so small that if you are caught out by the drop between the two highs you were pushing your luck!
 

Tranona

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Reeds is giving the times of the first high water and the other is giving the second. At neaps the second high water is higher and at springs the first is higher. If depths are critical then you need to get the local tidal curves which are on EasyTide, although on many days the difference in what is known as the "stand" is relatively small as are flows. The strong flows are in the 3 hours or so either side of low water.
 

grumpy_o_g

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South Coast
Reeds is giving the times of the first high water and the other is giving the second. At neaps the second high water is higher and at springs the first is higher. If depths are critical then you need to get the local tidal curves which are on EasyTide, although on many days the difference in what is known as the "stand" is relatively small as are flows. The strong flows are in the 3 hours or so either side of low water.


+1 http://www.ukho.gov.uk/EASYTIDE/EasyTide/ShowPrediction.aspx?PortID=0036A&PredictionLength=7
 
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