Wind against tide.

[wully]

Took a walk down to the Dorus Mhor today...pretty impressive from the land.

[Arghiro]

Nobody passing thro' then?

[wully]

Nobody passing thro' then?

Nope, but there were a few yotties who'd walked down to take a look from the safety of the shore

[Alcyone]

I went through there when we did our day skipper last year. Lovely day, and we timed it for slack, so flat calm, naturally.

Seeing it like that though, it reminds me of Ramsey Sound, and indeed, Jack Sound, here in Wales. In those places, on a big spring, as slack ends and wind over tide starts, it can tear up very quickly indeed, and get like that picture say 20 minutes after the current starts.

Is Dorus mor similar?

[claymore]

Nah - there's nothing in Wales as big as what there is in Scotland - except pillocks where they are much bigger.
Not your good self I hasten to add.

[Alcyone]

I'm sure you are right.

Meanwhile, I note that HW in the area of Dorus Mor this evening is a whopping 1.9m! That's getting on for one sixth of the height in Cardiff tonight, and nearly a third of the height in said Ramsey Sound.

Big boy.........

[claymore]

Aye - but a welsh metre is only one sixth of a scottish one....

[Alcyone]

Aye - but a welsh metre is only one sixth of a scottish one....

I think that might be Gills, you are thinking of.

I might, just might, concede that what you lack in quantity, tidewise, you make up for in quality.

To go back to the point though, I've dived, many of the Hebrides, Oban, Mull and Ullapool and the Summer Isles. No discernible current, to be honest. I was aware of strong currents as you get closer to the Corryvreckan, but had never heard of Dorus mor, until the missis and I sailed there last year, doing our day skipper course.

I am genuinely interested in these areas of bad tide, as I know little of them on the West coast.

[sahona]

Size doesn't matter.
How fast water has to pass back and forth through a small gap does. (well, height is only part of volume.....)
In this case, there is a considerable hidden obstacle that causes the upheaval, the wind just adds to it on occasion.

[claymore]

Exactly that
Rathlin, Islay and Cuan Sounds are all relatively narrow spots with strong flow - Even the Sound of Jura which is considerably wider, is a sod if you miss the tide!

[Alcyone]

Size doesn't matter.
How fast water has to pass back and forth through a small gap does. (well, height is only part of volume.....)
In this case, there is a considerable hidden obstacle that causes the upheaval, the wind just adds to it on occasion.

I disagree that size doesn't matter, otherwise there would be little difference between springs and neaps, and I suspect there is.

I was aware that there was a hidden obstacle in the Corryvreckan, as indeed there are in Ramsey and Jack Sound, down here.

Actually I'd forgotten Cuan. Been through there twice, and it was real fun.

So back to my original question, does it tend to pick up very quick, or is it more conventional, as rule of 12ths would suggest?

[claymore]

I think it follows the 12ths rule fairly closely with the big rush in the middle hours. Others may correct me but when we were sat aground in Cuan, I did have some time to ponder and from my own research concluded that at low water springs there is absolutely no slack water. It was just like a switch had been thrown! Of course the confusing thing about Dorus Mhor, Corryvreckan, Firth of Lorne and Cuan is that they can be shot at times that are completely unrelated to HW Dover, Sydney, Liverpool 8, Ecclefechan or even Oban as my tide guide will demonstrate.
Again - a brighter spark than I will need to help you access my definitive tide guide - a spark as bright as Silkie or even the Webmeister himself.

[Alcyone]

I think it follows the 12ths rule fairly closely with the big rush in the middle hours. Others may correct me but when we were sat aground in Cuan, I did have some time to ponder and from my own research concluded that at low water springs there is absolutely no slack water. It was just like a switch had been thrown! Of course the confusing thing about Dorus Mhor, Corryvreckan, Firth of Lorne and Cuan is that they can be shot at times that are completely unrelated to HW Dover, Sydney, Liverpool 8, Ecclefechan or even Oban as my tide guide will demonstrate.
Again - a brighter spark than I will need to help you access my definitive tide guide - a spark as bright as Silkie or even the Webmeister himself.

Aha! That's what I was after. Thanks.

Ramsey and Jack Sound are odd, in that slacks occur when tide should be at it's strongest, and vice versa. But I've seen this 'switch' effect that you speak of on springs. It just switches. I've actually seen a 20" buoy with hardly any tide on it when the tide is going one way, be dragged under with the tide going the other. In 7 minutes. I timed it.

Add that to a strong wind against the tide when it switches, and you can get nice, becoming awful conditions in a very short space of time.

As a diver, it didn't bother me, as we could get out of there fast. As a sailor now, it terrifies me, as I know it could take far longer to get out.

When we sailed through Dorus mor, the instructor gave me the distinct impression that it could be dodgy. That day, it was a pussycat!

Cheers.

[Nick]

.


- Although once again I feel obliged to point out that the orientation of the Sound of Luing is very definitely N-S

[Alcyone]

Now isn't that curious?

There's me trying to make comparisons between Scottish and Welsh sounds where the tide rips badly and it turns out the Scottish ones seem to have slacks about midway through the tide too.

Or am I reading this wrong?

Coincidence, I'm sure, but interesting, nevertheless.