001.22.500E 001.23.000E 001.23.500E 001.24.000E 001.24.500E 001.25.000E 001.25.500E 001.26.000E 65 7 61 64 8 6 54 49 Remains of the former The Little Sunk 8 74 4 49 Little Sunk Beacon 6 8 4 6 44 47 4 8 7 37 54 47 66 5 35 3 3 46 1 Barrow No 2 6 42 32 27 51.42.000N 74 55 45 4 3 51.42.000N 77 5 24 Fl(2)R.5s 7 44 37 32 27 65 4 3 Barrow 75 6 7 Obstn 3 24 22 Deep 43 33 N 68 3 32 2 53 42 4 23 4 1 62 5 3 25 8 36 14 76 73 58 4 42 3 34 28 7 4 6 27 28 65 53 41 26 6 75 6 5 3 33 2 11 42 9 34 32 5 56 46 32 24 12 7 36 5 5 43 34 3 28 22 64 3 28 2 46 5 315 126 6 43 4 4 29 1 1 33 2 82 128 7 54 37 36 5 9 41 3 29 2 11 7 5 42 4 2 4 9 72 36 47 3 3 79 63 41 38 2 27 4 44 36 34 9 75 55 36 6 42 3 32 28 91 6 4 92 8 5 41 39 3 3 29 27 11 85 4 433 1 3 6 36 4 9 8 6 42 38 32 29 109 51.41.500N 42 3 31 29 42 5 53 37 6 51.41.500N 3 35 89 7 5 4 36 72 28 4 10 41 35 35 6 45 39 3 32 51 8 3 3 3 3 56 44 7 36 32 S a n2 d4 w a7 v e s 7 36 31 4 87 1 5 41 9812 35 3 51 Notes 6 46 4 36 2 42 3 33 7 59 8 36 34 133 42 32 4 5 Depths in metres reduced to CD based upon 8 56 37 1 9 13 8 75 4 36 32 4 6 11 5 Port of London Authority live tide gauges. 51 4 3 36 36 4 68 13 8 48 1 9 34 41 38 39 10 73 43 35 32 46 Positions relate to WGS84 7 37 68 4 37 32 4 54 129 59 46 35 36 65 4 41 4 4 5 39 36 35 4 81 131 Soundings taken on 24.08.2019 3 3 44 66 46 41 7 34 3 41 5 101 13 2 122 5 35 6 39 34 39 8 Caution 5 4 43 5 48 36 3 36 4 98 Soundings taken on leisure equipment. Whilst 3 3 3 8 11 56 9 5 32 45 48 6 every care have been taken in the preparation 34 34 6 5 31 of this data, it cannot be guaranteed that these 36 38 81 12 51.41.000N 43 32 45 10 51.41.000N 36 34 3 12 depths will remain. 33 5 4 3 31 3 36 33 2 37 45 58 3 4 7 The magenta circles mark three wrecks and one 1 31 2 42 3 99 obstruction as recorded on the UK 4 6 5 Hydrographic Office Admiralty Chart 1975 3 S a n d 4 5 w a6 v e s 131 34 17 Wk 7 th 52 1 8 13 dated 11 July, 2019, Edition 28 4 4 10 4 8 14 49 Black Deep Little Sunk V1 2019 53 No Data 32 Wk © R. Gaspar 2019. All rights reserved 6 7 Wk 35 8 76 81 8 51.40.500N 5 51.40.500N 001.22.500E 001.23.000E 001.23.500E 001.24.000E 001.24.500E 001.25.000E 001.25.500E 001.26.000E Notes on the Little Sunk crossing Of the three crossing points of the Sunk Sand (SW Sunk, Middle Sunk or Little Sunk), the Little Sunk crossing is the most stable. It is not a swatchway, rather a relatively flat plateau on the Sand to the south-west of the Little Sunk. On the ‘plateau’ the depths are and have been largely stable for 20 years. Over that 20 years, the shape and extent of the knolls of the Little Sunk to the north-east have grown and shrunk. Back in the 1950’s the Little Sunk would have encroached on the crossing point and further back at the turn of the 20th century there would have been no crossing point. But, as I have said, for the last 20 years, it has been a nice wide stable crossing point about 1 nm wide between a cluster of three wrecks to the south-west and the obstacle to the north-east that is the remains of the Beacon. Arguably there is a trend for the Little Sunk to start extending towards the crossing point as you will see from the ‘finger’ of under 2m CD depths to the north-east but it is far from encroaching at the moment. It is, though, a ‘GPS crossing point’. It might be hoped that we could find a convenient transit on an avenue of Wind Farm turbines but to my mind nothing lines up, and indeed, even in misty weather it is impossible to identify any particular avenue of turbines. It would be very convenient for the Black Deep and Barrow Deep lateral buoyage to be adjacent but of course the logical position of the buoyage is to guard the knolls of the Little Sunk rather than mark ‘our’ crossing point. So GPS it must be. The general benefit of the crossing point is for those on passage between the Essex or Suffolk Rivers and the North Foreland. For those from or to the Essex Rivers who do not wish to use the SW Sunk swatchway (or indeed the Princes Channel/West Swin route) will find the Little Sunk crossing very handy. However, it adds about 4.5nm more than the SW Sunk route. For the Suffolk Rivers passage, the crossing is a benefit avoiding travelling a long 7nm sector along the Black Deep with the responsibility to keep clear of the large shipping which will be heading to and from the Thames. The Port of London Authority would appreciate us using the Black Deep as little as possible. Obviously using the Little Sunk will involve either Foulger’s Gat or Fisherman’s Gat and crossing the Black Deep channel. Bear in mind that the Black Deep uses the largest ships now and that they will travel fast – 18 to 20 kts – they will cover a nautical mile in a little over 3 minutes. So a diagonal course across the Black Deep to and from Foulger’s Gat will require good visibility; even if sailing, the shipping will have priority. With traffic about or poor visibility, crossing the channel at right angles would be prudent. It would also be prudent to monitor London VTS on VHF channel 69. Shipping call in their movements to VTS which can provide early warning; in bad visibility it would make sense to call up London VTS before crossing. One further general observation from experience: the Black Deep has some fast moving tide, particularly on spring flood when rates can reach 2.6kts and over 2kts on the ebb. Back in Decca days, we intended to find the Little Sunk crossing but with the spring ebb and a very brisk aft wind we reached the Black Deep No 3 in no time and missed the crossing! Some background about the survey The survey at the site took 3hrs 5 minutes and collected 12141 soundings from which you will obviously know, recorded one sounding every second. Each sounding is approximately 2.5m apart on each run: each run is approximately 270 metres apart. The chartlet overleaf uses 396 soundings, less than 4%, but I believe that provides an accurate representative picture of the crossing point. The survey revealed a wide area of sand waves. These images show the sand wave area compared to the rest of the crossing point. It is difficult to measure the height between the trough and peak of the sand waves but it could be as much as half a metre. Note though, I chose soundings from a pessimistic point of view: when plotting the sand waves areas I always select the ‘peaks’ rather than the troughs! Sand Wave area Clear of the Sand Wave area Across each of the runs the profile over the ‘plateau’ was similar. Here is an example profile approximately in the middle of the crossing area: The Black Deep edge is steeper than the Barrow Deep side. Towards the Little Sunk, the edge is markedly steeper. The profile clearly shows the sand wave area on the Black Deep side. On the survey day the weather was perfect; flat calm. The tide appeared to make no impact on the surface of the water in the sand wave area. On a windier day, wind over tide might make some difference but I would be surprised if it caused us any problem. Notes on Crossing the Thames Estuary (CTTE) Routes On the final page you will find the chartlet with CTTE details superimposed. I selected the waypoints back at the time of the first edition where there was less information and the waypoints were selected for prudence. The waypoints remain useful for the passage planning timing tables but those with experience can ‘trim some corners’.