River Deben/Trinity House

[shanemax]

Trinity House did a survey of the Deben Entrance in early February 2023. Will they being doing one in 2024 or will some one else take responsibility for the soundings. The chartlet usually gets printed in March each year.

 

[Cantata]

They do one every Spring. There’s a unique arrangement between them and Imrays which enables the chartlet to be drawn quickly and then published by us at East Coast Pilot.

 

[PeterBoater]

It's a pity, and potentially dangerous, that Navionics doesn't update the soundings and contour data when it updates the buoy positions. At present, the buoys on the chart are showing as leading across the drying bank, whereas the old channel, now closed, is showing as the one to use. A visiting stranger might think that the buoys are wrong and the soundings/contours are correct, despite the text warning about shifting situations.

 

[LittleSister]

A visiting stranger might think that the buoys are wrong and the soundings/contours are correct, despite the text warning about shifting situations.

That would be a perverse conclusion to draw in those circumstances, in my view. But anyone with that notion will likely quickly learn a hard lesson.

Charts are simplified representations of reality, not reality itself. I think it is incumbent on navigators to appreciate the inherent errors and approximations in charts, and the inevitable delay in updating revised information (where available - some areas have not been updated since the first survey, by lead-line hand-thrown from a boat with only visual position monitoring well over a century ago, and will likely remain that way).

I imagine that Navionics' contours will eventually be updated, but the buoys will quite likely have been moved yet again by then!

 

[dunedin]

It's a pity, and potentially dangerous, that Navionics doesn't update the soundings and contour data when it updates the buoy positions. At present, the buoys on the chart are showing as leading across the drying bank, whereas the old channel, now closed, is showing as the one to use. A visiting stranger might think that the buoys are wrong and the soundings/contours are correct, despite the text warning about shifting situations.

Navionics presumably relies on UKHO updating the base survey data. But then UKHO can take a further 3 months or so (after the commercial ENC charts are updated) to issue the updated data to leisure chart publishers. In the meantime Navionics may have seen the NtM about buoy locations and updated these. But if UKHO not issued updated soundings there isnt a lot Navionics et al can do - they can’t invent them.

 

[ex-Gladys]

Our local survey expert Tillergirl will wax lyrical on the shortcomings of Navionics...

 

[tillergirl]

they can’t invent them.

Are you really sure?

 

[tillergirl]

Navionics 090923 annotated by Roger Gaspar, on Flickr

? (of course this isn't at the Deben but it is an example of strange things.

I could show a few other examples. In fairness Navionics have a problem. They follow the UKHO SNC but no UKHO SNC chart displays the positon of the Woodbridge Haven and associated buoyage; the UKHO do update the contours and annotate the area 'Buoyage'. A note in the maargin of the relevant SNC it recommends not entering 'at any state of the tide without extensive local knowledge. Assistance with transit may be available, contact the Harbour Master'.

Crowd sourcing unfortunately has no routine QA process. Dick was instrumental in organising the relationship twixt Trinity House and Imray so the most reliable source of information at the Deben is either the East Coast Pilot or the Harbour Master.

 

[dunedin]

Navionics 090923 annotated by Roger Gaspar, on Flickr

? (of course this isn't at the Deben but it is an example of strange things.

I could show a few other examples. In fairness Navionics have a problem. They follow the UKHO SNC but no UKHO SNC chart displays the positon of the Woodbridge Haven and associated buoyage; the UKHO do update the contours and annotate the area 'Buoyage'. A note in the maargin of the relevant SNC it recommends not entering 'at any state of the tide without extensive local knowledge. Assistance with transit may be available, contact the Harbour Master'.

Crowd sourcing unfortunately has no routine QA process. Dick was instrumental in organising the relationship twixt Trinity House and Imray so the most reliable source of information at the Deben is either the East Coast Pilot or the Harbour Master.

Is this the Navionics base charts or with crowd sourced data ? The former is sourced largely from UKHO, in UK waters.
The latter is user beware of anybody is mad enough to switch on the optional crowd sourced data (though Navionics do claim there is a “routine QA process“ for this). I certainly do not use the crowd sourced overlay.

 

[tillergirl]

Yes, of course the base chart is sourced largely from the UKHO. This was not crowd soure. This is Navionics base chart and all their idea. Navionics placed that drying spot. There was no other similar drying spot that had been misplaced. Nobody has suggested any drying spot there for years. The trouble is one needs to know the detail to see the errors. The trouble is the SW knoll had moved and that was more critical and took Navionics too much time to correct.

 

[MikeBz]

There's a similar drying spot on Navionics on the Colne Bar SE of Colne Point, with detailed contours all around it if SonarChart is on. I've sailed over it a number of times and not seen any significant change in depth. I use it as a waypoint

 

[Aquaboy]

OH..... NO, the dreaded Deben entrance again........