Wansworth
Well-known member
Spanish news is warning of very high tides today and tomorrow
Exceptional high tides
- Thread starter Wansworth
- Start date
rogerthebodger
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Its because we have a super moon at the moment
capnsensible
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Shouldn't be a problem when we get back to Barcelona.
SaltIre
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Are they predicting very low tides as well?
Wansworth
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Yes,apparently moon is very near earth
LittleSister
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Yes,apparently moon is very near earth
Duck!
Tranona
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Autumn equinox. Here in Poole the range was 2.2m and low 0.3 this afternoon as I discovered when trying to take a heavy load (the bowsprit off the boat) down the ramp. Gave up as it would have run away. Low on Friday predicted to be 0.1m so most of the harbour will be exposed mud. Typical springs range is 1.8m
johnalison
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It’s funny how often exceptional tides happen.
Wansworth
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Obviously a slow news day here in Spain as it was a major news item
wonkywinch
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The coefficient tomorrow is 115%, so 21% stronger than a mean spring. And only the second highest coefficient this year (it was 117 on 12th March).
Hence why it's the Bramble Cricket Match on Friday at 0600.
Bramble Cricket Match - 20 September 2024 - Island Sailing Club
Hence why it's the Bramble Cricket Match on Friday at 0600.
Bramble Cricket Match - 20 September 2024 - Island Sailing Club
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Sandy
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Not that I understand coefficients; Plymouth is showing 131% for 19/09/2024.
What I do understand it tidal range AM 5.30m PM 5.50m
I am off to the Solent on Sunday should I be worried?
What I do understand it tidal range AM 5.30m PM 5.50m
I am off to the Solent on Sunday should I be worried?
wonkywinch
Well-known member
The things to consider are any parts you might normally be happy passing at low water will be shallower this LW. The tidal streams will also be stronger than indicated in your almanac as the range will be higher than mean springs used in the little pictures therefore more water to move in the same amount of time (6 hrs) so current will run faster.
HW and LW values will be correct as these take coefficient into account (but not local rainfall/air pressure variables).
Your 4kt mean spring tide will be 5kts. Use it in your favour and it will be a good thing.
Overfalls, wind against tide etc will be worse, again due to faster flow. All determined from a squiz at the coefficient. I use the Brest coefficient in the back of the Channel Almanac to glean the info (ignore the fact its for Brest, same blob of water, just the French use coefficients more due to the higher ranges around the French channel ports).
Frogmogman
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Really not exceptional, but entirely as expected for the Autumn equinox.
Here’s the curve for my home port.
Boathook
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Love to see pictures of Poole and Christchurch harbours at low water.
Bristolfashion
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Bristolfashion
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Happy!
We're going down to Lymington on the ebb & back up on the flood.
Weeeeeeeeeeeeeeeeh!
Even the wind is behaving.
Tranona
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This morning's low was 0.1 and this afternoon is 0.3. I will be there this afternoon and take a photo.
ProDave
Well-known member
Nothing exceptional.
One year I recall LW went below chart datum. Until then I thought chart datum was the lowest ever tide? Today it was 0.1m above chart datum.
One year I recall LW went below chart datum. Until then I thought chart datum was the lowest ever tide? Today it was 0.1m above chart datum.
Bobc
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Quayside road flooded at Belle Ile this evening.
Bristolfashion
Well-known member
This definition from the UKHO is pretty comprehensive,
"What is Chart Datum?
A:Answer Chart Datum is the plane below which all depths are published on a navigational chart. It is also the plane to which all tidal heights are referred, so by adding the tidal height to the charted depth, the true depth of water is determined. By international agreement Chart Datum is defined as a level so low that the tide will not frequently fall below it. In the United Kingdom, this level is normally approximately the level of Lowest Astronomical Tide.
The highest and lowest predicted tides that can occur are deemed Highest Astronomical Tide (HAT) and Lowest Astronomical Tide (LAT) respectively. These levels are the highest and lowest levels which can be predicted to occur under average meteorological conditions, and under any combination of astronomical conditions; these levels will not be reached every year. HAT and LAT are not the extreme levels which can be reached, as Storm Surges (wind-induced long period waves causing higher and lower-than-predicted levels to occur) and pressure effects can significantly alter the times and / or heights of the observed tide."
"What is Chart Datum?
A:Answer Chart Datum is the plane below which all depths are published on a navigational chart. It is also the plane to which all tidal heights are referred, so by adding the tidal height to the charted depth, the true depth of water is determined. By international agreement Chart Datum is defined as a level so low that the tide will not frequently fall below it. In the United Kingdom, this level is normally approximately the level of Lowest Astronomical Tide.
The highest and lowest predicted tides that can occur are deemed Highest Astronomical Tide (HAT) and Lowest Astronomical Tide (LAT) respectively. These levels are the highest and lowest levels which can be predicted to occur under average meteorological conditions, and under any combination of astronomical conditions; these levels will not be reached every year. HAT and LAT are not the extreme levels which can be reached, as Storm Surges (wind-induced long period waves causing higher and lower-than-predicted levels to occur) and pressure effects can significantly alter the times and / or heights of the observed tide."