Thank you Roger

[DanTribe]

I used the SW Sunk Swatchway again on Monday, as always, the info was much appreciated, especially on a grey and lumpy day.
I now think of the passage as Gaspar's Gat.
A very casual observation, there seemed to be a bit less water than expected at the Western waypoint, better water found slightly to the south.

 

[Bru]

I seen to recall that the esteemed Mr Gaspar wasn't too keen on "Gaspar's Gat" when it was previously suggested

I tend to think of it as "Tillergirl's Gat" but I can't help wondering if formally naming it would prompt it's demise

 

[tillergirl]

It is nice to hear the comments and that the info is useful; that's the point of it. I plan to do a re-survey next Spring. Let us hope that it is still there. Back in the '70s it stayed in exactly the same place as it is now for close on 10 years.... And then closed .....

As to the name.... Mr (rather too formal for me) Foulger was, I have been told that he was an experienced and talented sailor - I could (or would ever) hardly match his name. I just like pottering around the Estuary. I was whimsical and thought it ought to be Snark Gat. After all we have the ECF's equivalent of the The Times 'anyone heard the first cuckoo?' every Spring so each Spring we have the Hunting of the Snark. But then I read:

"We have sailed many months, we have sailed many weeks,
(Four weeks to the month you may mark),
But never as yet ('tis your Captain who speaks)
Have we caught the least glimpse of a Snark!

"We have sailed many weeks, we have sailed many days,
(Seven days to the week I allow),
But a Snark, on the which we might lovingly gaze,
We have never beheld till now!

... But then:

"'But oh, beamish nephew, beware of the day,
If your Snark be a Boojum! For then
You will softly and suddenly vanish away,
And never be met with again!'

And for certain at the end of the poem:

"It's a Snark!" was the sound that first came to their ears,
And seemed almost too good to be true.
Then followed a torrent of laughter and cheers:
Then the ominous words "It's a Boo—"

Then, silence. Some fancied they heard in the air
A weary and wandering sigh
That sounded like "-jum!" but the others declare
It was only a breeze that went by. :nonchalance:

They hunted till darkness came on, but they found
Not a button, or feather, or mark,
By which they could tell that they stood on the ground
Where the Baker had met with the Snark. :encouragement:

In the midst of the word he was trying to say,
In the midst of his laughter and glee,
He had softly and suddenly vanished away—
For the Snark was a Boojum, you see. :ambivalence:

So it probably ought not be 'Snark Gat' Perhaps it ought be called 'Boojum Gat'.

Ignore me. I 'm talking scribble.

 

[LittleSister]

I tend to think of it as "Tillergirl's Gat"

I like it! :encouragement: Can we get on to the Hydrographic Office and get it so marked on the charts?

 

[Habebty]

I like it! :encouragement: Can we get on to the Hydrographic Office and get it so marked on the charts?

+1 for services to the " desperate to make last orders"

 

[MountainGoat]

It is nice to hear the comments and that the info is useful; that's the point of it. I plan to do a re-survey next Spring. Let us hope that it is still there. Back in the '70s it stayed in exactly the same place as it is now for close on 10 years.... And then closed .....

What's slightly disconcerting is Navionics' Sonarchart shows the CTTE route as being high and dry!

It obviously isn't, and paradoxically their non-sonar chart has something more akin to what I presume reality actually is, but I'm surprised their Sonarchart is so wrong here when, I assume, lots of people locally are contributing to it.

Planning to cross from Burnham to Ramsgate by that route on the 30th, weather permitting. We send Sonarchart data to Navionics, and maybe that will improve matters.

To the OP, when you say less water, using Roger's waypoints, how shallow did it get? We'll be crossing at, looking at the tides for the 30th, at least 2.5m ACD (low water appears to be 1.6m ACD on that day). I'm guessing with our 1.75m draft we shouldn't have any problems at any state of tide if we stick to the current waypoints?

 

[tillergirl]

MG, can you get a screen grab of the Navionics Sonarchart and send me it as an attachment via info@crossingthethamesestuary.com ? I would like to see what might be wrong. The quick reference on the day, approaching the swatch listening into VHF69 the Port of London VTS will broadcast tide heights 15 minutes before and 15 minutes after the hour. Usually there are three bleeps announcing and then they will just say 'Walton [figures to decimal one point), Margate etc, Shivering Sands etc, Southend etc. You can regard the Margate figure as the height of tide at the swatch; Shivering Sands if you miss Margate will only be 0.1 of a metre out. On occasions it can miss out the broadcast when v. busy. If you have the Interweb on board you can always access the Margate tide gauge at: http://server2.pla.co.uk/Safety/Hydrography

 

[Champagne Murphy]

Gaspars gat sounds great but to avoid tempting fate how about Ghost gat?

 

[Bru]

What's slightly disconcerting is Navionics' Sonarchart shows the CTTE route as being high and dry!

I think you may need to re-download the data because looking on the Navionics web app, the sonar chart matches the standard chart quite closely and certainly doesn't show the route as high and dry

 

[MikeBz]

My IOS Navionics app charts are up-to-date (as of today). With SonarCharts on you see the SW Sunk swatchway correctly until you zoom in beyond a certain level, then it appears to revert to an earlier chart. This is the opposite of the 'Wouter the Router' effect, where he hit a reef because he failed to zoom in - in this case you would avoid a drying area which doesn't exist if you zoom in...

At this zoom level it looks OK:



Zoom in (and I mean in, more detail) just a tiny bit and it's wrong:

 

[MountainGoat]

Roger, have emailed as requested.

Mike - that's what I'm seeing as well. I think it shows standard Navionics regardless until you zoom in, even if sonarchart is selected.

There are two problems here. Problem 1 is that sonarchart does not show the current channel. Problem 2 is that it still shows the old channel.

Problem 1 should be fixed next time someone sails through there with sonar log upload turned on. Problem 2 highlights what I think is a fundamental problem with the sonarchart idea: it's never going to get fixed because that "passage" is now a sand bank and nobody is likely to sail over it in order to update the chart.

The sonarchart concept is great, but it's important to understand its limitations and quirks. User beware.

 

[MikeBz]

Problem 2 highlights what I think is a fundamental problem with the sonarchart idea: it's never going to get fixed because that "passage" is now a sand bank and nobody is likely to sail over it in order to update the chart.

That's a very good point. I'm becoming quite disillusioned with Navionics re their charts, particularly after a long exchange with their tech support recently which confirmed that there is no way to tell whether there are any updates pending for your chip - the only way to ensure it is up to date is to re-download all of the data (which is getting on for 1 Gb including sonar charts and community updates) periodically, whether there are any updates due or not, which must be near useless unless you can take the chip home and use your high-speed home broadband. That means I need to remember to bring the chip home from the boat regularly, and even more importantly remember to take it back again... Apologies for the drift...

 

[MountainGoat]

the only way to ensure it is up to date is to re-download all of the data (which is getting on for 1 Gb including sonar charts and community updates) periodically, whether there are any updates due or not, which must be near useless unless you can take the chip home and use your high-speed home broadband. That means I need to remember to bring the chip home from the boat regularly, and even more importantly remember to take it back again... Apologies for the drift...

This situation is a lot better if you have one of the plotters with wifi sync. All the Raymarine Lighthouse II plotters do. Mine's an A97 and all I need to do is open the Navionics app on my phone, let it update over the Internet, turn on wifi and it automatically refreshes the plotter. I do this every time I go on the boat and it takes about about as long as it takes for me to boil the kettle.

 

[MikeBz]

I've sent you a pm on this subject to cease my thread hijack...

 

[tillergirl]

MG has sent two images. The first is the sonar chart - That is a two year old out of date chart. Tear it up! The second was a current non-sonar chart - it's fine and correct.

I always record data to DGPS standards - not that there is much variation nowadays between DGPS and GPS. In fairness to the e-chart suppliers, keeping in touch on a global basis to the detail of a very small area is a challenge. Chart plotters are handy but....

 

[Bru]

I can confirm, cos I've just experimented, that the chart change is due to the (correct) standard Navionics chart being displayed when if Sonar Charts are selected until you zoom in. Then it switches to the (out of date in this case) Sonar chart

I have to confess that I largely ignore all user contributions to the Navionics charts and data cos I don't trust 'em!

 

[MountainGoat]

MG has sent two images. The first is the sonar chart - That is a two year old out of date chart. Tear it up! The second was a current non-sonar chart - it's fine and correct.

I always record data to DGPS standards - not that there is much variation nowadays between DGPS and GPS. In fairness to the e-chart suppliers, keeping in touch on a global basis to the detail of a very small area is a challenge. Chart plotters are handy but....

While the sonarchart approach scales, this instance shows the value of the personal surveying and curating that you do, particularly in an area like the Thames Estuary. I for one am very glad you're doing it.

 

[LittleSister]

While the sonarchart approach scales, this instance shows the value of the personal surveying and curating that you do, particularly in an area like the Thames Estuary. I for one am very glad you're doing it.

+1:encouragement:

 

[MountainGoat]

Update: I've submitted fresh sounder data to Navionics for the SW Sunk and their Sonarchart now incorporates it. If you're using Roger's waypoints, that is probably about as current as you're going to get for the time being (spoiler, there's plenty of water, if you use the waypoints).