Oban tides this weekend

[cpedw]

What's going on? According to my Tide Table, this Saturday 23/9, HW is at 1148 BST. On Sunday, it's 1501 BST. That's more than 3 hours difference in a day. I'm accustomed to a change of about 1-1.5 hours daily. Is it because it's very small springs, range only 1m.

Does it often do this sort of thing?

[Bodach na mara]

Unfortunately I can't keep 2 pages on my phone open to compare times so the figures that I quote here are approximately remembered, but there is an oddity. Just not as extreme as you quoted. Using a tide app the time of HW on Saturday is about 1130. On Sunday it is ~13.20 and on Monday it is ~ 15.30.

So instead of advancing about one hour per day it's advancing about 2 hours. It might be something to do with the equinox. My first thought was that someone was jumping the gun on the end of BST.

[Alan_D]

Reed's has HW Oban on Saturday at 10.48 UT, Sunday 14.01 and Monday 15.05
Admiralty Easytide has Saturday at 11.48 BST, Sunday 15.01 and Monday 16.05
WX Tide (using their own calculations) gives Saturday 11.32, Sunday 13.22 and Monday 15.21, all BST
The National Tidal and Sea Level Facility don't do Oban, but for Tobermory they offer 11.08,13.41 and 14.53, all UT, and you can go there and look at the actual levels after the event.

[cpedw]

So there's total agreement between Reeds and Easytide. NTSLF looks correct for Saturday (20 mins after Oban is the usually quoted figure) but Sunday looks to be way off. Does Oban have peculiar behaviour around neaps?

[Gardenshed]

[/img][/img]time differences between high and low times for Oban for 22-25 Sept and time difference between high tides
Data from the Imray Tides app
not the usual, regular 12 hours 25 mins between High Tides. Is this just a curiosity / one off, does it happen occasionally in Oban Bay...... or have we just never noticed!

LT 22/09/2023 04:40
HT 22/09/2023 10:40 06:00:00
LT 22/09/2023 17:20 06:40:00
HT 22/09/2023 22:50 05:30:00 12:10:00
LT 23/09/2023 06:10 07:20:00
HT 23/09/2023 12:00 05:50:00 13:10:00
LT 23/09/2023 18:50 06:50:00
HT 24/09/2023 00:30 05:40:00 12:30:00
LT 24/09/2023 07:50 07:20:00
HT 24/09/2023 14:50 07:00:00 14:20:00
LT 24/09/2023 20:30 05:40:00
HT 25/09/2023 03:40 07:10:00 12:50:00
LT 25/09/2023 09:10 05:30:00
HT 25/09/2023 16:00 06:50:00 12:20:00
LT 25/09/2023 22:00 06:00:00

sorry about the formatting. looks ok when I type in the post, but after submitting, the spacing between the columns disappears

[BlowingOldBoots]

A guess. I think it is to do with the small neap range, the shape of the land around the Oban area and relative strength of gravity acting on the water. It is a bit like High Pressures, Low Pressures and strong winds blowing from a certain direction for a long time. All can delay tide times. Perhaps, in this case, the data set recognises this for Oban when there is small neap range, gravity conditions and shape of land, and when the calculation is made, it takes that into account. Dunno really, a guess.

[Alan_D]

Looking at the Tobermory tide gauge on NTSLF the timings for Saturday and Sunday proved pretty accurate but the heights got progressively higher than predicted, presumably due to meteorological effects.

[cpedw]

It's happening again this weekend:
Sat HW Oban 11:47 BST, 2.8m
Sun HW Oban 15:39 BST 2.9m
I note that it's very small neap tides again, about 1m range but 4 hours change from one day to the next seems extraordinary. I expect 1 to 1.5 hours normally.

[Bodach na mara]

Well the phenomenon is not confined to Oban. I was looking at the Largs Yacht Haven booklet to find out the state of the tide for lift-out today and noticed that last week on consecutive days the time of high water advanced by over 2 hours.