Understanding tides

[ForeverYoung]

I keep thinking that I have a decent grasp of how tides work, and then the sea changes the rules again!

I was looking on tidelines at the section if water just off Leverburgh on the south of Harris.

The text here has me confused, how does this happen? It's says "At neaps in summer, tide runs SE all day and NW at night". I don't understand!

[Chris Bolton]

The tides in the Sound of Harris are unique. First surveyed by the interestingly named Captain Henry C Otter of the Royal Navy.

I don't know if there's an official explanation but my hypothesis is as follows (starting with the things you already know)

1. Tides are a result of the gravitational pull of the sun and the moon. Consider this as two separate patterns of movement that are superimposed. Normally the moon has most effect, and the sun adds to it to create spring tides, or is out of sync and produces neaps.

2. The actual direct pull of the moon and sun is small, but the sea sloshes from side to side of the seas and oceans and the small regular pulls build up that motion. The resulting 'wave' of tidal water means that high water is at different times along the coast.

3. Tides in the Sound of Harris are complicated because the tides in the Minch are not quite in sync with the tides in the Atlantic. Water flows through the Sound depending on which side is higher at the time.

4. As it's only the difference between the East and West sides that drives the tides, the normally bigger lunar component is a similar size to the solar component. In winter the sun is away down South and the moon dominates, as usual. In summer, the sun is more dominant and on neaps, where it's not aligned to the moon, the tides end up just following the sun, day and night.

This may be completely wrong but there are some ideas to play with!

[mrcharly]

That's a good summary.

It might be worth getting the local guidebook; Sea kayaking around the isles and st kilda. Presda press

[ForeverYoung]

The tides in the Sound of Harris are unique. First surveyed by the interestingly named Captain Henry C Otter of the Royal Navy.

I don't know if there's an official explanation but my hypothesis is as follows (starting with the things you already know)

1. Tides are a result of the gravitational pull of the sun and the moon. Consider this as two separate patterns of movement that are superimposed. Normally the moon has most effect, and the sun adds to it to create spring tides, or is out of sync and produces neaps.

2. The actual direct pull of the moon and sun is small, but the sea sloshes from side to side of the seas and oceans and the small regular pulls build up that motion. The resulting 'wave' of tidal water means that high water is at different times along the coast.

3. Tides in the Sound of Harris are complicated because the tides in the Minch are not quite in sync with the tides in the Atlantic. Water flows through the Sound depending on which side is higher at the time.

4. As it's only the difference between the East and West sides that drives the tides, the normally bigger lunar component is a similar size to the solar component. In winter the sun is away down South and the moon dominates, as usual. In summer, the sun is more dominant and on neaps, where it's not aligned to the moon, the tides end up just following the sun, day and night.

This may be completely wrong but there are some ideas to play with!

Thanks Chris, what a fascinating and crazy bit of water!!

[ForeverYoung]

That's a good summary.

It might be worth getting the local guidebook; Sea kayaking around the isles and st kilda. Presda press

Currently, I have no immediate plans to paddle up here. I was looking down on it from Ceapabhal and looking at all the streams which prompted me to look up tidelines to see what was going on.

I would love to get a boat up here sometime though! What a stunning area for it

[leighv]

This was a really interesting thread to read!

[mrcharly]

The OH are a brilliant place for sea kayaking. There is something to suit everyone.

The waters where I paddle have quite gentle tidal flows, because they are generally sea lochs with a V shape. Still significant range though. Springs are up to 5m, so you can find yourself with an extended scramble over rocky shores.

One of my favourite routes relies on getting the tide right; at high to mid-tide there is a narrow gap between main island and little islet. Tickles my humour to get the timing right and nip through the winding channel.

[Chris Bolton]

It might be worth getting the local guidebook; Sea kayaking around the isles and st kilda. Presda press

The guidebook I have, from Pesda Press is titled "Outer Hebrides Sea Kayaking". Is there another one? Mine just says "The tides in the Sound of Harris are notoriously unpredictable"!

[ChrisJK]

Forgive this interjection but even predictable tides catch out the unaware and even dimly aware as experienced by the RNLI in my locality
https://www.poetrybyheart.org.uk/poems/the-sands-of-dee

[mrcharly]

It might be worth getting the local guidebook; Sea kayaking around the isles and st kilda. Presda press

The guidebook I have, from Pesda Press is titled "Outer Hebrides Sea Kayaking". Is there another one? Mine just says "The tides in the Sound of Harris are notoriously unpredictable"!

I think I have a newer edition of the same book. Full title is:
Outer Hebrides
Sea Kayaking around the isles & St Kilda

It has a whole section on the Sound of Harris.

[Chris Bolton]

I think I have a newer edition of the same book… …It has a whole section on the Sound of Harris.

Thanks. Mine has 3 separate short trips on the edges of the Sound, but not a section as such. It's a fascinating place. My own exploration of it was cut short when my paddling companion had a diabetic hypo and I had to rescue him and get him ashore.