Notice to Mariners Week 43

[tillergirl]

Permanent

4 from UKHO

1. 5 reduction of depths at the Eagle shoal, the Colne Bar (two), in the Blackwater near to the Bench Head SHB and one near the Colne Bar buoy. Usual image at: http://www.crossingthethamesestuary.com/page9.html
2. A reduction of depth at one spot in the Warp - unlikely to hinder leisure craft;
3. A 'formal' legend for UKHO charts for warning the extension works of the Greater and Outer Gabbard Wind Farms. Image of course as above;
4. A temporary north cardinal buoy heading for the Slijkgat channel off Holland.

Temporary

1. River Thames - the Oikos Jetty Diving works extended for the 30th October. Small craft ought to be the other side of the Thames but the Divers are working close to the main channel;
2. Harwich Harbour - seasonal buoy removal on or around 23rd October;
3. Salvage of wreck near the Trinity buoy in the Sunk Precautionary Area. Works for 60 days so worth checking anyone coming this way;
4. The Broads - underwater and above water inspections are due to be undertaken on Reedham Swing Bridge: ******Wednesday 9th November 2016 and Somerleyton Swing Bridge: Thursday 10th November 2016
5. The Broads - Closure of Rockland Boat Dike & Rockland Staithe - closed to navigation for essential maintenance dredging Closed: Monday 14 November 2016 until Friday 23 December 2016 & Closed: Monday 9th January 2017 until Friday 20 January 2017
6. Dredging at the Port of Wells.

That's it.

 

[ianfr]

Thanks as always

Ian

 

[MikeBz]

That 0.3m drying height is a surprise. We almost always take a well inshore route across the Colne bar and have never had any scares in that area. I don't have a plot of the route unfortunately, but last time we came back (into the Colne from the East) we definitely went over the 7m hole (it is incredibly steep-sided) on a course which took us just inside Colne Pt (plenty of water just inside it) and never saw less than 3m on the sounder at around half flood. It would be interesting to have a poke around out there on a properly low tide.

 

[tillergirl]

The source of the NtM was Wessex Explorer which will have been one of those professional surveyors that been announced a couple of months back they were surveying from Harwich sort of to the Bench Head. I noted they were stopping short of the Spitway which seems an odd decision. In fairness that will reduced to chart datum so it might never actually show.

Sliding round the Colne Point would have been 'inside' that drying patch - nice. And those holes are almost like 'well' shaped they are so steep. It's all a bit odd really: if we assume the seabed is largely 7m deep with the Bar heaped up by the process of the tide (some heap), how come those big holes don't get filled in? Very odd.

On another point, have a surprising thought at a cross section of Mersea Quarters (one cross section between the red cans to the green cones). Just if anyone might think it it's flat! :nonchalance:

On another point, works on Heybridge Basin lock is full ahead albeit some craft are still squeezing by. It is supposed to be close from 1st November but they have constructed two new lock-gates on the lock side this week - very impressive work, and a barge is moored just outside of the lock digging out the channel right up to the large gates. I suppose they will close the large electric gate and shutter up canal side to empty out the lock to pick out the old pair of gates.

 

[Bru]

I suppose they will close the large electric gate and shutter up canal side to empty out the lock to pick out the old pair of gates.

They'll have a job cos they're replacing that too and I'm pretty sure the old one has already been removed

 

[MikeBz]

The Navionics Sonar Chart has an extremely localised 11m hole WSW of that drying point at a distance of ~0.17nm (and a 13.5m hole SW @ 0.4nm). Maybe I'm passing just S of the drying point and over that 11m hole. I'll have to put the drying point in the plotter next year and see if I can find it (bump).

It is intriguting how these holes and bumps haven't just been levelled out over time. Some of them do appear to come up by 5m+ within 10m or so of distance - you'd have a job to climb out of it if it wasn't filled with water.

 

[Habebty]

The Navionics Sonar Chart has an extremely localised 11m hole WSW of that drying point at a distance of ~0.17nm (and a 13.5m hole SW @ 0.4nm). Maybe I'm passing just S of the drying point and over that 11m hole. I'll have to put the drying point in the plotter next year and see if I can find it (bump).

It is intriguting how these holes and bumps haven't just been levelled out over time. Some of them do appear to come up by 5m+ within 10m or so of distance - you'd have a job to climb out of it if it wasn't filled with water.

Yes, I always wondered how another hole, "The Well" (12.2m deep) near Stone Banks formed. I can only suppose some glacial erratic ripped it out of the clay, but can't figure why it hasn't filled with sand or shingle?

 

[tillergirl]

They'll have a job cos they're replacing that too and I'm pretty sure the old one has already been removed

Coo, yes, someone's nicked the 'old' electric gate. Not that it was that 'old' cos I remember it being installed.