Calculating a route across multiple tides

I believe John Goode campaigned for the RYA to adopt the Reeve Foulkes Tidal Atlases for some time but without success.

Tidal Diamonds allow the RYA to set a navigation question along the lines of ''a yacht is at Position A at X hours.What is the Course To Steer for Y Buoy? (Use Tidal Diamond 'A' ). Anyone using the correct methods should be able to come up with an answer that is within a pencil lead thickness of that arrived at by the person setting the exam.

This is all fine and and dandy and saves a lot of argument in class but does NOT - in my opinion - prepare the student for the practicalities of navigating a small craft at sea.

For that the Reeve Foulkes Tidal Atlas gets my vote every time.
 
jimbaerselman said:
toad_oftoadhall said:
Well yes, but when you sit down and work out the tangent it really makes little difference if you did decide to go with a straight track.
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Errm. Forgive the selective quote. But if you're in a tiddler of a boat in a light wind (3kts?) and you're crossing the channel in spring tides, you'll be spending much of your cruising passage going nowhere, just pointing into tide trying to keep track. First one way, then the other.
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I suspect you are unique in being capable of sailing almost at right angles to your destination without actually noticing and correcting, but just for you I'll rephrase so you don't do it. Please substitute as follows:

"Well yes, but when you sit down and work out the tangent it usually makes little difference if you did decide to go with a straight track. Not that I can see any reason why you would. (The usual motive given for a hypothetical person to keep a straight track is going X Channel and steering to a waypoint all the way but in reality you wouldn't do that in a yacht because even if your plan was to steer to a waypoint you'd still steer to the compass for the first 12ish hours or so.)

Obviously if you're racing it's all a bit different. “
 
toad_oftoadhall said:
I suspect you are unique in being capable of sailing almost at right angles to your destination without actually noticing and correcting, but just for you I'll rephrase so you don't do it. Please substitute as follows:

"Well yes, but when you sit down and work out the tangent it usually makes little difference if you did decide to go with a straight track. Not that I can see any reason why you would. (The usual motive given for a hypothetical person to keep a straight track is going X Channel and steering to a waypoint all the way but in reality you wouldn't do that in a yacht because even if your plan was to steer to a waypoint you'd still steer to the compass for the first 12ish hours or so.)

Obviously if you're racing it's all a bit different. “
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[Obviously if you're racing it's all a bit different. “]

very similar just work out the vector more carefully
 
toad_oftoadhall said:
No I didn't. You said: "very similar just work out the vector more carefully"

In fact not similar at all.

The two strategies are totally different. Sticking to a COG would be totally ineffective if you were racing. Every minute might count.

How are they similar?
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work out the vector & steer compass course was what i inferred. not steer to a WP.

last May we went to Oostende. a fellow forumite in a larger boat took something like 16 hrs & sailed 90 mls he ended up down wind down tide.Unlike me he had an expensive education & is teaching others in Cambridge.
we left an hr after him took 12hrs sailed 73 mls. he arrived when we were in the club having had a shower & a few biers
 
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sailorman said:
work out the vector & steer compass course was what i inferred. not steer to a WP.

last May we went to Oostende. a fellow forumite in a larger boat took something like 16 hrs & sailed 90 mls he ended up down wind down tide.Unlike me he had an expensive education & is teaching others in Cambridge.
we left an hr after him took 12hrs sailed 73 mls. he arrived when we were in the club having had a shower & a few biers
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So not so similar after all!

LOL!
 
toad_oftoadhall said:
So not so similar after all!

LOL!
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might have been :D

our track that trip

P5243115.jpg
 
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somerset said:
Tidal Diamonds ....saves a lot of argument in class but does NOT - in my opinion - prepare the student for the practicalities of navigating a small craft at sea.
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I say again: the RYA has specified that students should be taught to use both tidal diamonds and tidal stream atlasses for at least 35 years to my certain knowledge. It's there in black and white in the syllabuses, in their textbooks and course notes, and in their Practice Nav Tables. What more do you want?
 
Agreed the RYA teaches both atlases and diamonds (which are always available on the chart), and I don't see any difference between students' ability to use them both, in CTS and EP exercises, which are typically one hour.

When it comes to passage planning, Reeve Fowkes makes it all much easier, and it's the best approach to use in practice, so I make sure the class knows about it. His commentary on tide planning is very good.

Reeve-Fowkes covers the North Sea up to the Wash, and St George's Channel.
 
timbartlett said:
I say again: the RYA has specified that students should be taught to use both tidal diamonds and tidal stream atlasses for at least 35 years to my certain knowledge. It's there in black and white in the syllabuses, in their textbooks and course notes, and in their Practice Nav Tables. What more do you want?
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Yes Tidal Atlases are covered in the RYA Syllabus but they do not figure when it comes to drawing lines on charts.In order to achieve a precise answer the students are told which Tidal Diamond to use in the exercises and exams.As I say this is excellent at avoiding disputes but not very good in the practical sense.Especially when the students come to do their practical courses where Tidal Diamonds do not figure very largely if at all in my experience.

BTW are you THE Tim Bartlett of text book fame? if so please accept my apologies for any hint of lese majeste in this post.:)
 
Ubergeekian said:
A quick google suggests that they only cover the south coast and the southern North Sea. Is that right?
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The Western Channel one covers about as far north as Arklow & Pwllheli. It's a shame they don't go further.

However I also have doubts about referencing everything to Cherbourg, which they do, when you get beyond the Central Channel. I know that Reeds habit of referencing the tidal chartlets for the Irish Sea to Dover can be pretty inaccurate at times.
 
Course to Steer

I have a handout which I dish out to them's that wants it. It explains the procedure with tidal diamonds and with tidal stream atlas'. If anyone wants a copy, send me your email address and I will send out a copy. Don't expect an instant response, I am off sailing until Sunday.

Sticky
 
somerset said:
.In order to achieve a precise answer the students are told which Tidal Diamond to use in the exercises and exams.
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When the tide atlas figures in an exercise students are not told which arrow to use, and frequently have to think hard about which to use - just like in practice.
 
Skysail said:
When the tide atlas figures in an exercise students are not told which arrow to use, and frequently have to think hard about which to use - just like in practice.
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Exactly.My point is that the tidal atlas should be the source for tidal stream data from Day 1 of any shorebased course (Be it Reeve Foulkes or Admiralty ones).It would lead to differing answers and take more time but this could be got over by examiners showing an acceptable 'position of uncertainty' in their model answers.

Who knows? It could mean that more skippers might have a clue what to do if the GPS packs up.
 
Good thread!

I'm planning my first Channel crossing this year, without the aid of a chart plotter or passage planning software, so getting it right using paper materials and traditional navigation is a bit important to me.

Studying my copy of the Admiralty Tidal Atlas for the Channel, I find that the numerical data is quite sparsely given, with lots of bare arrows - which means a fair bit of interpolation or guesswork where it comes to deciding the actual tidal rate at any given position. (And unless its bang on springs or neaps, that means further interpolating a load of interpolations!)

So I've ordered a copy of the full Reeves-Faulks handbook combined with all the atlasses (less than a tenner new through Amazon marketplace), which I gather presents the data more 'flowingly' and in a fashion that's easier to pluck at any given position.
 
Hi Vince,

Have you got any nav gear on board? i.e. autopilot, GPS?
If so as an easy fix use your course over ground and it's corresponding CTS to program the auto pilot, and keep an eye on that. Adjust it every hour or so, or where needed.

If not I agree the easiest way would be to take the general effect of tides etc would have on you over the whole trip and compensate accordingly, although hour by hour will be more accurate.
 
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