New Solent banks drying above CD according to iPad Navionics

[Angele]

That's on my printed Imray chart, but the correction sheet then adds a further drying bank which would appear to be the same one shown on Navionics.

Pete

Pete

I'm wanting to look into this further. Are you sure the same drying banks also appears on a correction to the Imray charts (and not simply reference to an isolated hazard)? I have read the NtoMs for Imray's C3 and C15 charts (also chart pack 2200) and there is nothing to suggest this is a large bank, only this:

7 Peel Bank
Insert Obstn, drying height -1.4m, in 50°45’.37N 1°12’.84W (ILNW 373/13)

 

[prv]

I'm wanting to look into this further. Are you sure the same drying banks also appears on a correction to the Imray charts (and not simply reference to an isolated hazard)? I have read the NtoMs for Imray's C3 and C15 charts (also chart pack 2200) and there is nothing to suggest this is a large bank, only this:

7 Peel Bank
Insert Obstn, drying height -1.4m, in 50°45’.37N 1°12’.84W (ILNW 373/13)

I think that's the one I meant. You're right that it doesn't indicate a large bank, but the height is the same - drying to 1.4m.

Your survey didn't find it, and with low tides routinely below 1m I'm sure it would have been noticed if really there.

Pete

 

[Cohoe]

Thank you for the UKHO address Angele,
My letter to UKHO, Navionics and copy Keran Flatt. I couldn't find an email for the RYA.

Dear Sir,
I am surprised to see new drying banks appearing on the Solent charts displayed on my new Raymarine E7 using Navionic charts Nov 2013.
I have sailed the Solent for 40 years and know this to be inaccurate.
I have been chatting on the "yachting monthly scuttlebut forum" and local yachtsman have an opinion that this email may be beneficial.

So on Tuesday 26th Nov 2013 I sailed over the length of the indicated banks in order to prove the depth of these banks. Looking at the chart you would think it dries out more than the Bramble Bank a celebrated and well marked drying bank in the Central Solent. I have never seen Peel or Mother Bank dry out even at extreme low water springs.

On Tuesday I observed a minimum of 2.1m below CD whilst traversing the bank, approximate position 50 45.3N 001 12.9W at 1315z. I estimated the height of tide at this time to be approximately 2.5m at Portsmouth or 2.3m at Cowes. There was exceptional high pressure of 1040mb with light winds, perhaps subduing the height of tide by approx. 0.2m. I have ensured my depth meter is calibrated to a reasonable accuracy for a yacht by use of a lead line and would estimate that it is correct +/- 0.1m. The meter is calibrated to the bottom of my keel and the yacht has a draught of 1.6m. I observed whilst traversing the bank a minimum of 3.0m under my keel. Using the maximum predicted tidal height at Portsmouth of 2.5m at 1315z. Not making any allowance for air pressure which would have subdued the tidal height. Subtracting a reasonable error of 10% then I conclude that the depth of water could have been 3.0m + 1.6m - 2.5m max tidal height at Portsmouth at 1315z. Then the bank could not have been shallower than 1.8m below CD at its highest point observed on a course of 285 degrees across the bank.
I know this is nowhere near the accuracy of a professional survey but I wish to point out that the updated Navionics chart indicates a drying height of +1.4m at 50 45.2 N 00112.9 W.
I would disagree by a difference of over 3m and if the Navionics chart were correct I would definitely have been well aground.

I made similar observation at 1335z at position 50 45.5 N 001 14.1 W . A minimum depth under my keel of 3.2m.

I have proved that the inner passage towards Gillkicker from Portsmouth Harbour Entrance position 50 47.3 N 001 6.7 W between BC Outer and the Seawall still has at least 0.3m below CD. Not +1.2m drying above CD.

I believe my out of date paper Imray chart 2009, Admiralty charts 2005 and Garmin chartplotter 2009 and Digitalyacht Cmaps 2009 showing approximately 2m of water below CD are still valid for the area of Peel and Mother Bank. So having recently purchased a Raymarine E7 chartplotter with the latest Navionics Gold Chart No 46XG Nov 2013 I am disappointed in the charting accuracy.

I hope you are able to investigate these anomalies. I would assume UKHO is the surveying authority for the area so I hope my observation may be of some benefit.

Regards D

 

[Angele]

I think that's the one I meant. You're right that it doesn't indicate a large bank, but the height is the same - drying to 1.4m.

Coincidence, I think. On Admiralty charts (including the online ones at VisitMy Harbour) there is an isolated obstruction in that position with a drying height of 1.4m and the legend "rep (1986)" - so nothing new.

 

[prv]

Coincidence, I think. On Admiralty charts (including the online ones at VisitMy Harbour) there is an isolated obstruction in that position with a drying height of 1.4m and the legend "rep (1986)" - so nothing new.

I'm at work so can't check my chart - but there certainly was an obstruction (rep sometime in the 80s) already printed. So that's not what the correction refers to. I didn't think it was listed as drying though.

Pete

 

[Angele]

I'm at work so can't check my chart - but there certainly was an obstruction (rep sometime in the 80s) already printed. So that's not what the correction refers to. I didn't think it was listed as drying though.

Pete

The obstruction showing on the Admiralty chart is dotted circle enclosing "greenish" area and in its centre the values 1 (with the underline) and a small 4 - so definitely a drying height.

See http://www.visitmyharbour.com/harbours/solent/wootton-creek/chart/8A9DF37F2D622/wootton-creek/fishbourne-approach-chart

Its latitude is (about) 50deg 45.4N. Although I can't read the longitude from the online charts, since the scale at the edges does not show, it does appear to be roughly half or the way W to E from Peel and Wootton NCM (so, approx 1 deg 12.8 W). This is consistent with the position in the Imray chart update.

I'm assuming that, if there ever was anything there, it has long gone. If not, surely someone would have reported it more recently than 1986 (as it would be visible at low water springs if the depth is accurate).

 

[onesea]

I'm assuming that, if there ever was anything there, it has long gone. If not, surely someone would have reported it more recently than 1986 (as it would be visible at low water springs if the depth is accurate).

The problem is for the UKHO is proving it is not there!

Usual story what if some one hits it, or the wreck that the latest round of gales spring tides turns over in that vicinity in the sand etc etc

Its out of shipping channels no ones hit the symbol so it is no problem to anyone, if some one hits something in that area its on the chart!

 

[Angele]

The problem is for the UKHO is proving it is not there!

Usual story what if some one hits it, or the wreck that the latest round of gales spring tides turns over in that vicinity in the sand etc etc

Its out of shipping channels no ones hit the symbol so it is no problem to anyone, if some one hits something in that area its on the chart!

If you read the response from UKHO to my query to them, you will see that they do have recent survey data that has not yet been incorporated into the charts. I presume this has been produced using modern methods, in which case they probably can say with a high degree of confidence whether that hazard is real or no longer exists (if it ever did). They just haven't got round to telling us yet...

Anyhow, my comment was about what I do with the information that is showing on my chart - about a hazard that was reported in 1986 in one of the busiest areas of leisure boating in the world - and not about whether it is still correct for it to appear on Admiralty charts. Sub-conciously I have done a risk assessment that chooses to blank it out of my mind, but I am clearly taking a risk that it may exist (as indeed does anyone else sailing in that area who doesn't give it a wide berth). (For clarity, what we are talking about here is an isolated hazard and not the vast drying banks showing on the Navionics electronic charts).

 

[onesea]

Angele, I was not having ago at you. It was observation, it reminded me of a guy I sailed once who had worked on patrol boats in the Aus Navy north of Australia where large areas are uncharted.

He deliberately went looking for some shoals many reported along time ago! he KNEW nothing was there but the chart could not me amended cause even as an Officer he could not prove nothing was there!

 

[AntarcticPilot]

Angele, I was not having ago at you. It was observation, it reminded me of a guy I sailed once who had worked on patrol boats in the Aus Navy north of Australia where large areas are uncharted.

He deliberately went looking for some shoals many reported along time ago! he KNEW nothing was there but the chart could not me amended cause even as an Officer he could not prove nothing was there!

Proving a negative is notoriously impossible. I've encountered the same issue in Antarctica, where mamy dirty icebergs have been reported as islands, named and in the gazetteers. It is nearly impossible ti get them removed, even when all the combined resources of satellite images and hydrographic survey say there's nothing there!

 

[Mark-1]

Wooton Creek looks wrong too.

 

[Cohoe]

A chap from Navionics phoned from Australia today and left a message. He said thanks for the email and they are aware of several errors in their charts ( Peel Bank, Mother Bank etc). They said they were fixing the problem and a new update should be published shortly. It will be interesting to see if they correct the Inner Swashway too. I hope the update is free since I just purchased the chart plotter and charts this November !
Cohoe

 

[Angele]

A chap from Navionics phoned from Australia today and left a message. He said thanks for the email and they are aware of several errors in their charts ( Peel Bank, Mother Bank etc). They said they were fixing the problem and a new update should be published shortly. It will be interesting to see if they correct the Inner Swashway too.

It makes you wonder what quality control processes they go through before issuing a chart update, bearing in mind that we use charts to make critical decisions that have a bearing on our safety. If I do go to LIBS (unlikely, but you never know), and I see someone on the Navionics stand (assuming there is one) I think I shall be giving them a pretty tough time about it.

I hope the update is free since I just purchased the chart plotter and charts this November !
Cohoe

I would think it should. It is a while since I bought any chart updates from Navionics, but I'm pretty sure it entitled you to free updates for a period after purchase. Was it 12 months?

 

[Cohoe]

Dear sir, thank you for phoning to say you would be updating the charts for Peel and Mother Banks which have now reverted to the original soundings of approximately -2m below CD.
I see you have now updated the charting of the area and I can update my new Navionics charts for my new Raymarine E7 plotter.
However I can still see that the soundings of a spit running out past BC Outer over the Portsmouth Inner Swashway is still inaccurate. I have sailed this area recently and can assure you that the passage between the sea wall and BC Outer does not dry. Since your recent amendment 5th Dec you are indicating an even higher drying spit with a +2m contour and a spot sounding of +1.7m above CD. It previously showed +1.2m drying above CD at position 50 47.34 N 001 6.73 W. This is complete rubbish. Will it soon be a mountain? Where do you get your information from and why is it so unreliable? When the tide gauge is 2m at Portsmouth entrance I can still take this inner passage when outbound to Gilkicker Point passing NORTH of the BC outer passage in my 1.6m draught yacht and have 1m under the keel. This is in accordance with instruction written on the BC Outer mark. Outbound leave to Port. Inbound leave to Starboard. There is rumour of some concrete blocks off the seawall but to date touch wood on passing in and out of the Portsmouth Inner Swashway within 20m of the BC Outer mark I have found no hinderance to the passage.
Regards D


Thank you for contacting Navionics. We appreciate you taking the time to notify us of any discrepancies you may have found in our product. We will be investigating your report and will contact you when and if the error is corrected. Thank you for your time.

Best regards,
Navionics Cartography Team

Dear Sir,

I am surprised to see new drying banks appearing on the Solent charts displayed on my new Raymarine E7 using Navionic charts Nov 2013. I have sailed the Solent for 40 years and know this to be inaccurate.

So on Tuesday 26th Nov 2013 I sailed over the length of the indicated banks in order to prove the depth of these banks. Looking at the chart you would think it dries out more than the Bramble Bank a celebrated and well marked drying bank in the Central Solent. I have never seen Peel or Mother Bank dry out even at extreme low water springs.

On Tuesday I observed a minimum of 2.1m below CD whilst traversing the bank, approximate position 50 45.3N 001 12.9W at 1315z. I estimated the height of tide at this time to be approximately 2.5m at Portsmouth or 2.3m at Cowes. There was exceptional high pressure of 1040mb with light winds, perhaps subduing the height of tide by approx. 0.2m. I have ensured my depth meter is calibrated to a reasonable accuracy for a yacht by use of a plumb line and would estimate that it is correct +/- 0.1m. The meter is calibrated to the bottom of my keel and the yacht has a draught of 1.6m. I observed whilst traversing the bank a minimum of 3.0m under my keel. Using the maximum predicted tidal height at Portsmouth of 2.5m at 1315z. Not making any allowance for air pressure which would have subdued the tidal height. Subtracting a reasonable error of 10% then I conclude that the depth of water could have been 3.0m + 1.6m - 2.5m max tidal height at Portsmouth at 1315z. Then the bank could not have been shallower than 1.8m below CD at its highest point observed on a course of 285 degrees across the bank.
I know this nowhere near the accuracy of a professional survey but I wish to point out that the updated Navionics chart indicates a drying height of +1.4m at 50 45.2 N 00112.9 W.
I would disagree by a difference of over 3m and if the Navionics chart were correct I would definitely have been well aground.

I made similar observation at 1335z at position 50 45.5 N 001 14.1 W . A minimum depth under my keel of 3.2m.

I have proved that the inner passage towards Gillkicker from Portsmouth Harbour Entrance position 50 47.3 N 001 6.7 W between BC Outer and the Seawall still has at least 0.3m below CD. Not +1.2m drying above CD.

I believe my out of date paper Imray chart 2009, Admiralty charts 2005 and Garmin chartplotter 2009 and Digitalyacht Cmaps 2009 showing approximately 2m of water below CD are still valid for the area of Peel and Mother Bank. So having recently purchased a Raymarine E7 chartplotter with the latest Navionics Gold Chart No 46XG Nov 2013 I am disappointed in the charting accuracy.

I hope you are able to investigate these anomalies. I would assume UKHO is the surveying authority for the area so I hope my observation may be of some benefit.

 

[Martin_J]

And what's more they have now re-added the West Winner spit just to the West of Langstone Harbour entrance.

(You will see in my earlier posting in this thread that they had removed it which was what I'd expected!)

 

[Angele]

The Navionics Webapp (http://navionics.com/en/webapp) gives the choice of two views - with either "Sonar Charts" on or off. This is supposed to give more detailed info on the seabed, but using the same underlying survey data. In most places that appears to be exactly what it does. However, in certain cases, the two views say very different things. The Inner Swashway at the entrance to Portsmouth Harbour and the West Winner spit are two of the most obvious of these. The "conventional" view seems to be in line with other charts (e.g. Admiralty), but the Sonar Charts is showing some very unlikely data.

An even more extreme example is on the other side of Portsmouth Harbour, off Southsea beach. Not somewhere I would ever sail, since I would be in the small boat channel, but very alarming differences. In one place where the conventional view shows depths below chart datum, the Sonar Charts gives a drying height of 7.1m. Since that is way above HAT, it shouldn't be shown as a green drying height, it would be solid land.

How on earth can they have data for the same place that disagrees by over 7m?

 

[ChiPete]

Apologies for thread drift but whilst we're talking about iPad Navionics issues - I've got the iPad version of Reeds. For some reason the neaps and springs notations on the tide tables stop after January 2014. Has anyone else with the iPad version come across this issue?