That's worrying; my paper charts are on board so can't cross reference, but those coordinates have come straight from my tablet plotter and place me comfortably clear with a min depth of 4.2m.
Image9 by Roger Gaspar, on Flickr
Good morning. I am looking into a route from Burnham on Crouch towards Ramsgate. plotting a route across the Thames estuary brings me almost automatically to the question ‘ can I or can’t I sail between west sunk and middle sunk. When I looked into this I found this post on yew date t august 2021. In your reply you refer to your website but I can’t seem to find it and you mention a survey to be carried out. Is there recent data on this area and where can I find it? You also might say do not attempt this passage? anyway can you help me out in this?Not surprised at all I'm afraid. I am tempted to suggest you buy a copy of the book and if on the reader's Update list you would have had a warning from me on 7th July about the Middle Sunk! But I mustn't say that because I probably ought to have posted an explicit warning on the Forum in respect of the MIddle and SW Sunk crossing points. There is clear information about the SW Sunk crossing but I was intending to try to conduct a survey on the Middle Sunk before I could post. And then my main computer blew. And then my printer wore out. And now I have broken my laptop - which temporarily precludes me from havesting data on surveys. XO-Gladys and I are planning to get down to the Middle Sunk in two weeks time subject to a nice flat day and a working laptop.
Several points:
DO NOT RELY ON PAPER CHARTS OR ELECTRONIC CHARTS IN RESPECT TO CROSSING EITHER THE SW SUNK OR MIDDLE SUNK. Paper charts are out of date in respect to those particular localised areas and in consequence electonic charts are also out of date.
I am afraid it is necessary to read the small print! UKHO chart 1975 (Thames Estuary - Northern Part) is the primary source in that area. Electronic charts follow that chart. On chart 1975 there is an inset box showing the 'Sources' (of data). For the area of the Middle Sunk you encountered you will see the area was drawn on data between 1993 and 2012! That is the latest data used on paper charts and electronic charts. If you look at the SW Sunk area the source is shown as Commercial Surveys 2004 to 2019. The 2019 data is the data I supplied to the UKHO. I have also supplied 2020 and 2021 data in respect of the SW Sunk contemporaneously. But certainly the 2021 data was received to late for the latest Edition of chart 1975 which was in July.
The change of the SW Sunk data in 2020 was very slight; a migration slightly to the north-east. This year there has been a significant similar north-east migration. The consequence is that electronic charting is quite troublesome (I will avoid saying 'dangerous' as plotter usually warn 'depths may vary'). It is troublesome because following the best water on the plotter would put you straight over the SW knoll. There has already been one stranding this season doing that. I had produced a 2021 chartlet with revised waypoints and a number of forumites have confirmed the swatch is fine.
As to the Middle Sunk: There are very few professional surveys of the banks. In the past the Port of London Authority have sent their rib over some of the banks as a adjunct of major surveys of the channels but of course only when the conditions are fine. As far as I am aware the Middle Sunk was last looked at by the PLA in 2015. That showed an extension of the north-east finger of the Middle Sunk which dried in places at chart datum i.e that area was significantly less helpful. Since the finger had been extending since 2012 I would suggest it is not unreasonable to expect the 'finger' to get worse since 2015. Hence I have been recommending my readers NOT to use the Middle Sunk at the moment
I had made a sort of 'study' piece in 2016 to try to understand how the Sunk Sand was developing as the PLA had kindly sent me their data. Here it is here:
Finger over the Middle Sunk by Roger Gaspar, on Flickr
Can I stress this is not an official chart or chartlet, I drew it to try to understand how the Middle Sunk was developing. And it is 5 years old data in an area that can be changing so please, nobody rely on this image! It is merely to show that that area is certainly out of date on all current charts - paper or electronic.
The Little Sunk is the most predictable and stable area to cross. It adds miles for the Essex Rivers but is shorter for the Suffolk Rivers. I last surveyed there in 2019 which had little change over the previous years and there is a downloadable chartlet on my website - as indeed there is the 2021 chartlet of the SW Sunk.
Yesterday we sailed towards Ramsgate and made thankful use of your hints and suggestions. I have plotted the three waypoints on my route and without any problem we went through the channel between middle sunk and sw sunk. As you mentioned, we use navionics most recent chart, our chart is quite accurate, It that I can only confirm no I have sailed the route. For any following Thames estuary crossings I will check you work again and again we say thank you for your effort.There are three 'logical' crossing places of the Sunk Sand: the SW Sunk, the Middle Sunk or the Little Sunk. You can download the chartlets for the SW Sunk and the Little Sunk at Downloads. The SW Sunk was surveyed this year. It is fine and it is shortest twixt Burnham and Ramsgate. Use the three wpts and drop down into Fisherman's Gat. The Little Sunk hasn't been surveyed for a couple of years but is a stable area. It is longer, dragging you a little over to the east and invites you to use Foulger's Gat through the Wind Farm - which is entirely permissable but may be subject to some maintenance exclusion zones. They are doing diving work on the cables until the end of September. You can of course use Fisherman's Gat from the Little Sunk.
The Middle Sunk is feasible but frankly is a little pointless from Burnham. There is a nasty 'finger' of sand extending from the Middle Sunk which obstructs a nice north-south crossing. It is possible to go round the tip of the finger but then you need to avoid the remains of the old Sunk Beacon which lies on the sea bed. No buoyage marking that but its location is well known. I say pointless because the Middle Sunk crossing doesn't save you any distance from Burnham and needs a little concentration. If you have Navionics or C-Map with an 2022 update you can see the 'finger'. If you have 2021 or previous version, it will not be update. We did a partial survey in latter of 2021 and the Port of London Authority similarly did a partial. It needs to be fully covered but I haven't been able to go down there this season so far.
My tables will compare passage plan times and show how best to time the route for the quickest passages.
Hope this helps.
PS: use the SW Sunk
Thanks for sharing that. I am sure it was very worrying at the time and glad the outcome was good. Good decision not to delay alerting the CG.
It is beyond my control. (No, just re-run the vid. We were further south but the tide issue would certainly still have been into play.
d the 2022 chartlet and
