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Impact of tidal streams when crossing English Channel

Boh999

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Joined
27 Sep 2015
Messages
72
Hi!

Rookie question. Experienced of sailing in the Baltic Sea. Took courses in tidal sailing (theory) before departing on a cross-Atlantic voyage. Currently in Ooestende, crossing to Dover soon. Please look at this picture from our pilot book "The Shell Channel Pilot" by Tom Cunciiffe.

I understand this, if I was navigating with charts, old-fashioned way. However we are also using the plotter and the Navionics app. We roughly do like this in harbour:
1. Check Reeds.
2. Verify in Navionis app.
3. Talk to other sailors, it seems wise to leave when others do.

However we will have stream both ways on this 60 Nm passage, so one guy said it's unnecessary to do the math + Dover is an all-tide harbour.

Of course winds needs to be checked etc, just considering the tidal part here.

My question:
We got a Raymarine ES75 with Navionics Gold charts for Europe, a few years old. There is tidal info in the charts, I have turned on the blue tidal arrow on the boat icon, you can click on stream and tidal icons and animate etc. Useful.

If I make a waypoint at Dover, will Raymarine do the best route as described in Mr Cuncliff's book (see image)?

When sailing over the Baltic Sea, the plotter does indeed take drift into account, so I do get the shortest route when sailing towards a waypoint on the other side of the Sea using the Autopilot. Will it do this also in this tidal scenario when facing different currents for the whole passage?

Cheers
IMG_1777.JPG
 

Tranona

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10 Nov 2007
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32,180
You really don't need to use the plotter at all. Just work out the tidal streams that will affect you during your passage as explained in the book and set a course that takes into account the net effect to arrive slightly upstream of your destination. Your track on your chart plotter in real time will show an S shaped curve but note your position regularly to see if you are deviating significantly from your expected track. Around 3-4 hours out review your position and replot a course to take into account tide and sailing conditions for the rest of the passage, still aiming up tide of the entrance.
 

johnalison

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Essex
As per Tranona. But be aware that the stream at Dover can run at around 3kn, which can make a late arrival very frustrating. I have sailed to Dover from Calais in the ridiculously short time of about 2.5 hrs, but get it wrong and you will be hanging around for hours. If you are sailing across the tides in this area, my rough and ready guide would be to head 15 degrees towards the tide and make a correction a couple of hours before arrival but the TSS off Dover may not allow this.
 

lw395

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16 May 2007
Messages
42,083
I've no idea of the capabilities of a particular model of chart plotter.
Maybe it will tell you to obey the TSS and cross at a heading 90 degrees to it?

I think you need to have a broad understanding of which way the tide is going, when it turns and where it's strongest.
Likewise if you are sailing, what is the wind doing for the duration of the crossing?
Then make a plan of how to cross.
Calculating the CTS exactly isn't much help.
 

Daydream believer

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Southminster, essex
Unlike the example in the book you might be sailing from Ostend in between the sand banks down past Nieuport & Dunkirk which is not a straight line. Then when you get further along you will be sailing along the coast with route changes to avoid ferries at Calais etc.Once nearing Cap Griz Nez you will be turning North to cross the shipping lanes so instead of going either with or against the tide you will be more at right angles.
you would possibly (from memory & without looking at the charts) go to ZC2 buoy & turn North & in that situation you get tides around Cap Griz Nez that turn the corner a bit.
You might take a line towards Ramsgate at something like 270 degrees & do a wiggle around the shipping lanes then head towards south Foreland using the strong SW stream, but in any event the tides will not always be at the same right angle as in the example in the book.
Hence, with both routes the compensation theory does not actually work in the same way . (However,I would need to check the charts to see that what i am saying is correct )

From memory I think last time I did this, a few years ago, I did Ostend-Dunkirk using the tide, then across to the UK using the west going stream again as it runs quite strong.
 

tillergirl

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West Mersea
If you are crossing from off Calais to Dover you could always use my Free Supplement see http://www.crossingthethamesestuary.com/page6.html. Much of the Supplement won't apply (ignore all the Dover to Ramsgate stuff - this relates to my book) but the northbound Table T allows you to optimise crossing the TSS (according to the rules) and very easily working out how to benefit from the SW going tide. Chart plotters can't do that, the tables can!
 

jwilson

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22 Jul 2006
Messages
5,156
I don't know of any normal plotter system that will automatically generate a best course to steer with varying cross-tides during a passage - every one I've ever met just holds you on a straight over the ground course which with typical channel tides takes you longer than an curved or S-shaped over the ground course.
 

johnalison

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I don't know of any normal plotter system that will automatically generate a best course to steer with varying cross-tides during a passage - every one I've ever met just holds you on a straight over the ground course which with typical channel tides takes you longer than an curved or S-shaped over the ground course.
That might be the case mid-channel but Boulogne/Calais to Dover or Ramsgate will normally be done on a single tide. What with having to comply with the TSS, an approximate offset may be all that conditions allow, and without correcting for the shipping, an 'autopilot' course would be close enough.
 

alant

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Joined
30 May 2001
Messages
37,616
Location
UK - Solent region
Hi!

Rookie question. Experienced of sailing in the Baltic Sea. Took courses in tidal sailing (theory) before departing on a cross-Atlantic voyage. Currently in Ooestende, crossing to Dover soon. Please look at this picture from our pilot book "The Shell Channel Pilot" by Tom Cunciiffe.

I understand this, if I was navigating with charts, old-fashioned way. However we are also using the plotter and the Navionics app. We roughly do like this in harbour:
1. Check Reeds.
2. Verify in Navionis app.
3. Talk to other sailors, it seems wise to leave when others do.

However we will have stream both ways on this 60 Nm passage, so one guy said it's unnecessary to do the math + Dover is an all-tide harbour.

Of course winds needs to be checked etc, just considering the tidal part here.

My question:
We got a Raymarine ES75 with Navionics Gold charts for Europe, a few years old. There is tidal info in the charts, I have turned on the blue tidal arrow on the boat icon, you can click on stream and tidal icons and animate etc. Useful.

If I make a waypoint at Dover, will Raymarine do the best route as described in Mr Cuncliff's book (see image)?

When sailing over the Baltic Sea, the plotter does indeed take drift into account, so I do get the shortest route when sailing towards a waypoint on the other side of the Sea using the Autopilot. Will it do this also in this tidal scenario when facing different currents for the whole passage?

Cheers
View attachment 72355
Add up all east going tides, subtract west going tides (or vice versa) use resultant figure as your tide vector to work out course to steer.
 

Tranona

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Add up all east going tides, subtract west going tides (or vice versa) use resultant figure as your tide vector to work out course to steer.
See posts#2&3

Do you ever have anything new to say? or read previous posts in the same thread?
 

jwilson

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Messages
5,156
That might be the case mid-channel but Boulogne/Calais to Dover or Ramsgate will normally be done on a single tide. What with having to comply with the TSS, an approximate offset may be all that conditions allow, and without correcting for the shipping, an 'autopilot' course would be close enough.
Agree entirely as long as you calculate total predicted tidal offset and steer a fixed course to allow for that. Obviously in real life you check and adjust course a bit if needed as you approach destination. Too may people though now have plotters connected to autopilots and just tell it to go to a destination waypoint - this will just follow the straight over the ground track - thus losing out to someone who does it properly.

The OP asked "... if I make a waypoint at Dover, will Raymarine do the best route" - I think it won't.
 

TSB240

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Joined
17 Feb 2010
Messages
2,710
Hi!
My question:
We got a Raymarine ES75 with Navionics Gold charts for Europe, a few years old. There is tidal info in the charts. Will it do this also in this tidal scenario when facing different currents for the whole passage?

Cheers
View attachment 72355
NO. Your chartplotter may have tidal information for you to access. It does not use it at all to automatically modify your plotted course.
 

alant

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See posts#2&3

Do you ever have anything new to say? or read previous posts in the same thread?
What apart from raging piles, is your problem?
Do you really expect people to read the whole thread before posting?
Anyway, my reply was more succinct than your rambling prose, or should I genuflect in your honour beforehand? :rolleyes:
 
Last edited:

Tranona

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What apart from raging piles, is your problem?
Do you really expect people to read the whole thread before posting?
Anyway, my reply was more succinct than your rambling prose, or should I genuflect in your honour beforehand? :rolleyes:
Sometimes I wonder why you bother at all when your reply was repeating what had already been said.

Surely it is common courtesy to read what has already been posted. It also avoids making you look a bit foolish.
 

alant

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Sometimes I wonder why you bother at all when your reply was repeating what had already been said.

Surely it is common courtesy to read what has already been posted. It also avoids making you look a bit foolish.
That is simply your opinion & doesn't really matter.
 

Seajet

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Boh999,

anyway two important things; as Tranona briefly mentioned, as with all crossings aim to arrive say a mile uptide of destination, so if visibility is bad, electrics fail etc you know which way to go.

Secondly Dover is very busy with strict harbour control, so check up on this and the procedures ( I have never sailed there by small boat ) before you go and have VHF on the correct channel on approach.


I'm afraid it is not the most attractive of English ports ! I hope you have the time to come further west to Chichester Harbour and the Solent to see real British sailing and countryside.
 
Last edited:

alant

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UK - Solent region
Boh999,

anyway two important things; as Tranona briefly mentioned, as with all crossings aim to arrive say a mile uptide of destination, so if visibility is bad, electrics fail etc you know which way to go.

Secondly Dover is very busy with strict harbour control, so check up on this and the procedures ( I have never sailed there by small boat ) before you go and have VHF on the correct channel on approach.


I'm afraid it is not the most attractive of English ports ! I hope you have the time to come further west to Chichester Harbour and the Solent to see real British sailing and countryside.
Most small boats use the Western Entrance at Dover, to avoid getting in the way of the frequent commercial stuff using the Eastern Entrance & is much closer to the marina.
 

Daydream believer

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Most small boats use the Western Entrance at Dover, to avoid getting in the way of the frequent commercial stuff using the Eastern Entrance & is much closer to the marina.
I have been there many times. Coming from Ostend one would use the eastern end. No point in struggling to get to the other end especially if rough or adverse tide
Dover port control are quite accommodating to yachts, but need to be advised of approach when nearing the port
 

johnalison

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I have been there many times. Coming from Ostend one would use the eastern end. No point in struggling to get to the other end especially if rough or adverse tide
Dover port control are quite accommodating to yachts, but need to be advised of approach when nearing the port
Yes, there's nothing particularly difficult about the Eastern entrance, and you may even have the pleasure of holding up a ferry for a while. It is usual to contact them early, when you will be told when to contact them again, usually a few cables off the entrance, where you will probably be instructed to wait north of the entrance, clear of shipping. They will then call you when you are free to enter, when you will be instructed to make 'best speed' to the western harbour.
 
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