Why no tidal currents in Northern Spain

[robertager1962]

I wonder if anyone can help with a puzzle.
We are currently wintering in Northern Spain (A Coruna) and we have pretty big tides here yet there are no tidal currents.
When we travelled along Brittany with tidal ranges about the same, we had awesome tidal currents and I don't really understand why.

 

[Little Dorrit]

I'm not an expert but if you Google amphidromic point or tidal node you might be able to understand the phenomenon, on the other hand I could be completely misleading you. Either way you'll have some fun reseaching I'm sure.

 

[macd]

I thought amphidromes, such as the one off Islay, are areas of low tidal range rather than necessarily of current (but I could be diametrically wrong). Might the slight currents robertager describes be more to do with the narrowness of the continental shelf off N Spain (typically <20M, compared to 100 or more off Brittany); and maybe the relative absence of choke points?

I daresay Antarcticpilot will be along to educate us, as he so often does...

 

[Sandy]

I wonder if anyone can help with a puzzle.
We are currently wintering in Northern Spain (A Coruna) and we have pretty big tides here yet there are no tidal currents.
When we travelled along Brittany with tidal ranges about the same, we had awesome tidal currents and I don't really understand why.

Tides are the complex interaction between sea and land. Relax, work them and have a beer.

 

[Little Dorrit]

I thought amphidromes, such as the one off Islay, are areas of low tidal range rather than necessarily of current (but I could be diametrically wrong). Might the slight currents robertager describes be more to do with the narrowness of the continental shelf off N Spain (typically <20M, compared to 100 or more off Brittany); and maybe the relative absence of choke points?

I daresay Antarcticpilot will be along to educate us, as he so often does...

It wouldn't be the first time I've been completely wrong about something.

 

[coopec]

I wonder if anyone can help with a puzzle.
We are currently wintering in Northern Spain (A Coruna) and we have pretty big tides here yet there are no tidal currents.
When we travelled along Brittany with tidal ranges about the same, we had awesome tidal currents and I don't really understand why.

Wouldn't tidal currents depend a lot on the the shape of the seabed near the shore? If a given amount of water (tide) has to flow over a restricted area (shallow seabed near the shore) it will have to move faster than the water of the deep ocean. You would expect the current at the Straits of Gibraltar would be strong because of the movement of water in and out of the Mediterranean.

Imagine tidal water flowing through a narrow inlet the current would be enormous. I bet the waters of Northern Spain are deep with little current. I've just been doing some research and I find it very complicated. Maybe this will help us both?

NEW Straits of Gibraltar tidal model

TIDETECH NEWS

Port of Spain and Approaches (Marine Chart : CB_GB_0474_0)

Tide predictions for any location in the world

 

[macd]

Coopec: I'm certainly no authority on the subject, but regarding your general suggestion can I perhaps refer you to post #3?
You might also note that the Port of Spain you linked to is in the Caribbean.

 

[coopec]

Coopec: I'm certainly no authority on the subject, but regarding your general suggestion can I perhaps refer you to post #3?
You might also note that the Port of Spain you linked to is in the Caribbean.

Yes I'm like you - no authority. But great minds think alike!

Regarding Port of Spain. I was bewildered when I saw that because I hadn't come across a port in Spain called Port of Spain (Mind you I am 12000 mile away so I could be forgiven) Now I want to know the major port but I'll have to look at a map. Geeez! (Valencia, Algeciras, Barcelona and Bilbao)

 

[macd]

Mind you I am 12000 mile away

Nah, Perth's not even a thousand miles away
A few tinnies of Swan will see you right. Cheers.

 

[Wansworth]

The water runs in and out the rias but as it’s open to the Atlantic it doesn’t get compressed to form tidal streams but there is surface drift heading south in general,but there is a stream going north at lower depths as shown when bodies appeared on the beach at Finisterre from a bus crash up the river river Douro

 

[goeasy123]

Wansworth, water is an uncompressible liquid.

The answer is.... the gravitational effects of the moon and sun pulls or pushes the Atlantic body of water up or down. As water is uncompressible replacement water must come from somewhere to fill or empty a potential void. In the case of N. Spain this water comes through the Straits of Gib and the English channel thus creating tidal flows there. There is nowhere (significant) on the N. Spanish coast for a large amount of water to come from. Therefore there is little tidal stream. The water just goes up and down and in and out of the Rias.

You get tidal streams on the French Atlantic coast created in part by the English Channel flow and the shape of the coast, but also the relatively large bodies for water and islands around, for example, Morbihan, Rad de Brest and the Gironde estuary.

There are also large scale non-tidal currents, generally pervasive with seasonable variation. The Gulf Stream is an example.

BTW, robertager1962 are you in Marina A Coruna? Say hola to Keiran for me.

 

[robertager1962]

Wansworth, water is an uncompressible liquid.

The answer is.... the gravitational effects of the moon and sun pulls or pushes the Atlantic body of water up or down. As water is uncompressible replacement water must come from somewhere to fill or empty a potential void. In the case of N. Spain this water comes through the Straits of Gib and the English channel thus creating tidal flows there. There is nowhere (significant) on the N. Spanish coast for a large amount of water to come from. Therefore there is little tidal stream. The water just goes up and down and in and out of the Rias.

You get tidal streams on the French Atlantic coast created in part by the English Channel flow and the shape of the coast, but also the relatively large bodies for water and islands around, for example, Morbihan, Rad de Brest and the Gironde estuary.

There are also large scale non-tidal currents, generally pervasive with seasonable variation. The Gulf Stream is an example.

BTW, robertager1962 are you in Marina A Coruna? Say hola to Keiran for me.

Thanks Andy. I can understand this now and it all makes perfect sense. The trouble is that none of the pilot books talk about tides when you get further South than Gironde which sort of leaves you wondering. The rise and fall of the tide here is huge and as I was brought up sailing in and around the Channel, it baffled me. Strange though that even the double harbour of Marina Real seems to have no current either in or out, just wave surges.

When we were heading across from Bilbao to Coruna, we had a strange Easterly flow along the Northern coast of about 1 knot and I think that the thought was that this was a weather phenomenon rather than tidal, trouble is when you are only travelling at 5 knots, this can quite a difference to journey length over a 12 hour period, so you would think it would be better documented.

We are in Marina Real as the A Coruna AKA Parrotts Marina is very prone to the swell and pretty uncomfortable at the moment. Even where we are we are we still do get thrown about a bit and I have now snapped four mooring compensators. Does Keiran work at the Marina or is he living there? I met a great guy who started off with a very strange accent but as we spoke in English together his Irish came through. He has been living with his Spanish wife for 10 years here.

Robert

 

[robertager1962]

Thanks everyone for your great advice and links, really useful. I am looking forward to our next adventure to Ria's as soon as the Spring arrives.

Robert

 

[goeasy123]

Thanks Andy. I can understand this now and it all makes perfect sense. The trouble is that none of the pilot books talk about tides when you get further South than Gironde which sort of leaves you wondering. The rise and fall of the tide here is huge and as I was brought up sailing in and around the Channel, it baffled me. Strange though that even the double harbour of Marina Real seems to have no current either in or out, just wave surges.

When we were heading across from Bilbao to Coruna, we had a strange Easterly flow along the Northern coast of about 1 knot and I think that the thought was that this was a weather phenomenon rather than tidal, trouble is when you are only travelling at 5 knots, this can quite a difference to journey length over a 12 hour period, so you would think it would be better documented.

We are in Marina Real as the A Coruna AKA Parrotts Marina is very prone to the swell and pretty uncomfortable at the moment. Even where we are we are we still do get thrown about a bit and I have now snapped four mooring compensators. Does Keiran work at the Marina or is he living there? I met a great guy who started off with a very strange accent but as we spoke in English together his Irish came through. He has been living with his Spanish wife for 10 years here.

Robert

 

[goeasy123]

Robert, here's how I learned about it.... I had an embarrassing dialogue with Imray. I bought their tidal app and used it very successfully from Cherbourg to the Gironde. When I upgrade to get the data that covers N. Spain I complained that there were no tidal streams indicated. It took a few attempts by patient tech support to get me to realise there were no tidal streams.... Doh!!

Keiran's looking after our boat in M A C. He Irish, married to a Spanish lady and lives in Spain. They just had a baby. Accent!! I'm Irish and I have trouble uderstanding him. He does a great job a pays a lot of attention to detail.

We'll see you around the Rias... Najad 400, Ca Canny.

 

[franksingleton]

Wansworth, water is an uncompressible liquid.

The answer is.... the gravitational effects of the moon and sun pulls or pushes the Atlantic body of water up or down. As water is uncompressible replacement water must come from somewhere to fill or empty a potential void. In the case of N. Spain this water comes through the Straits of Gib and the English channel thus creating tidal flows there. There is nowhere (significant) on the N. Spanish coast for a large amount of water to come from. Therefore there is little tidal stream. The water just goes up and down and in and out of the Rias.

You get tidal streams on the French Atlantic coast created in part by the English Channel flow and the shape of the coast, but also the relatively large bodies for water and islands around, for example, Morbihan, Rad de Brest and the Gironde estuary.

There are also large scale non-tidal currents, generally pervasive with seasonable variation. The Gulf Stream is an example.

BTW, robertager1962 are you in Marina A Coruna? Say hola to Keiran for me.

To amplify that slightly, tidal currents are strong from the Raz de Sein northwards but comparatively weaker the further south you go towards Spain. That is apart from duch areas as the entrance to the Morbihan and the Etel Where there are large bodies of water.

 

[robertager1962]

Robert, here's how I learned about it.... I had an embarrassing dialogue with Imray. I bought their tidal app and used it very successfully from Cherbourg to the Gironde. When I upgrade to get the data that covers N. Spain I complained that there were no tidal streams indicated. It took a few attempts by patient tech support to get me to realise there were no tidal streams.... Doh!!

Keiran's looking after our boat in M A C. He Irish, married to a Spanish lady and lives in Spain. They just had a baby. Accent!! I'm Irish and I have trouble uderstanding him. He does a great job a pays a lot of attention to detail.

We'll see you around the Rias... Najad 400, Ca Canny.

I think

 

[robertager1962]

Hi Andy
I am almost sure that I have met Kieren as the Irish chap he told me that he has been in Spain with his wife for 10 years and had just had a baby (can't be two such people both Irish). Yes really nice guy. I will probably be seeing him in a couple of weeks as I am going to top up the diesel tank with my gerry can (also gives me an excuse to take out Trinka sailing tender out for a romp.) I will pass on your best wishes.

Glad then that I am not the only one puzzled by the lack of tidal streams. The only cock up I made was leaving from La Rochelle on a mega low tide and experiencing a foul tide for about 3 hours. After the Raz du Seine I pretty much ignored the tides as they were negligible and we had fabulous sailing with the spinnaker up all day and romping along at just under 7 knots. We loved Northern Spain, especially Lannes (what a magical place) but motored all the way from Bilbao to A Coruna as the wind was either non existent or on the nose.

Look forward to seeing you. I am planning on spending about a month in the Rias before heading south. We are the Southerly with the tender on Davitts called Hoopla. Cool beer or hot cup of tea waiting for you (depends on weather.)

Robert