ex-Gladys
Well-known member
Navionics doesn't even keep up with UKHO NtM's!
Deben and Ore entrances - update
- Thread starter Cantata
- Start date
Johnah
Well-known member
Here are a couple of photos from LW today (29th March) but unfortunately only at a minimum of 1.5m above CD.
Am fairly sure the spit to the North of the channel (RHS on top photo) stretches right out to the Mid Knoll S H buoy in the foreground.
And one looking out to sea :-
Am fairly sure the spit to the North of the channel (RHS on top photo) stretches right out to the Mid Knoll S H buoy in the foreground.
And one looking out to sea :-
PeterWright
Well-known member
Thanks, John.
Your photoa and videos have become an established part of navigating the Deben entrance.
Peter.
Your photoa and videos have become an established part of navigating the Deben entrance.
Peter.
Johnah
Well-known member
Thanks Peter.
Here's an idea of what was lurking beneath the surface before the buoys were moved, LWS late February at 0.2m above CD.
Now have to wait until the next spring tide to see where the buoys have been laid in relation to this, and the long spit may have moved since the photo was taken.
Here's an idea of what was lurking beneath the surface before the buoys were moved, LWS late February at 0.2m above CD.
Now have to wait until the next spring tide to see where the buoys have been laid in relation to this, and the long spit may have moved since the photo was taken.
westhinder
Well-known member
A big thank you to all those involved in these essential chartlets and pictures
mullet
Active member
Very thoughtful of someone to build a Martello tower in line with a course along the new channel. 
Yorkshire Exile
Active member
That's a wonderful photograph and it appears to show how the bank on the left also has a developed spit running roughly South East then curving to the East. So the start of the channel from seaward is between the ends of those two spits at the bottom pf the photo. This maybe be obvious to many but it's fascinating to me!
miles from the sea
Member
Looks like Weir could do with being moved further south
Johnah
Well-known member
Here's a small video of the entrance at 0.5m above Harwich CD.
The recent wet, windy and foggy weather stopped me getting it when the tide was at an even lower level during LWS, but this shows a fair amount of the exposed knolls.
Deben entrance April 2023
The recent wet, windy and foggy weather stopped me getting it when the tide was at an even lower level during LWS, but this shows a fair amount of the exposed knolls.
Deben entrance April 2023
miles from the sea
Member
Navionics have updated the Deben entrance buoys so I have removed the community user added versions
Johnah
Well-known member
Now that my Moody 31 is launched (drawing 1.6m), I took a trip through the Deben entrance at half tide on Friday in calm conditions to see what's what. My friend also took his Starlight 36 through at HW today and we compared our findings.
We both found that the shoal section between the inshore Deben SH buoy and the Knoll Spit PH buoy is the shallowest section. This is where the river splits into two channels, one going via the shore (last year's entrance channel) and the other out to the South East, the new entrance channel. The bar itself by the Mid Knoll SH buoy seems to be just that bit deeper.
For me at half tide, the outer shoals were just showing (see below) so for people coming in a a couple of hours before HW, they are likely to be covered. The West Knoll PH buoy is to the left of the mast.
The depth coming in was fine from the outer Mid Knoll SH buoy to the West Knoll PH buoy (above) then it reduced to the minimum just between the last two Deben SH and the Knoll Spit buoys.
Photo below is the Knoll Spit PH buoy at near the shallowest section.
We both kept to the middle of the channel which is quite narrow at times. We also noticed how the depth wasn't so good if we started exploring from side to side. We kept away from the Knoll Spit PH buoy above as we are fairly sure the buoy sinker is sitting on the spit and that could be a real keel cruncher when the tide is down.
As our yachts sometimes need to get out of the river as early as possible, then the more information we can get the better. Please don't take this as advice as this is best left to the experts, and I have only done it once, but you can get an idea from the photos what you will see when coming into the Deben.
We both found that the shoal section between the inshore Deben SH buoy and the Knoll Spit PH buoy is the shallowest section. This is where the river splits into two channels, one going via the shore (last year's entrance channel) and the other out to the South East, the new entrance channel. The bar itself by the Mid Knoll SH buoy seems to be just that bit deeper.
For me at half tide, the outer shoals were just showing (see below) so for people coming in a a couple of hours before HW, they are likely to be covered. The West Knoll PH buoy is to the left of the mast.
The depth coming in was fine from the outer Mid Knoll SH buoy to the West Knoll PH buoy (above) then it reduced to the minimum just between the last two Deben SH and the Knoll Spit buoys.
Photo below is the Knoll Spit PH buoy at near the shallowest section.
We both kept to the middle of the channel which is quite narrow at times. We also noticed how the depth wasn't so good if we started exploring from side to side. We kept away from the Knoll Spit PH buoy above as we are fairly sure the buoy sinker is sitting on the spit and that could be a real keel cruncher when the tide is down.
As our yachts sometimes need to get out of the river as early as possible, then the more information we can get the better. Please don't take this as advice as this is best left to the experts, and I have only done it once, but you can get an idea from the photos what you will see when coming into the Deben.
PeterWright
Well-known member
Hi John,
Thank you for that further information. Would you let us know what the least depth you observed was on this exploratory trip, please? That is death below waterline rather than below keel. Thanks,
Peter.
Thank you for that further information. Would you let us know what the least depth you observed was on this exploratory trip, please? That is death below waterline rather than below keel. Thanks,
Peter.
Yorkshire Exile
Active member
Have there been any fatalities there?
PeterWright
Well-known member
I don't believe so, at least not recently. Just my clumsy fingers and telephone keyboard as that's all I have access to while sat in Stansted Airport's departure lounge.
Mind you, a & P are opposite ends of the keyboard, so it may be the dreaded auto correct!
Peter
.
Mind you, a & P are opposite ends of the keyboard, so it may be the dreaded auto correct!
Peter
.
LittleSister
Well-known member
Your phone probably detected you wondering if there was six feet under, and jumped to conclusions.
Johnah
Well-known member
Hi Peter,
I left off the figures as I had two readings so don't hold me to them, but after leaving the Deben buoy I had a total depth of 2.1m. I was probably a bit off line to the North because when coming back just a few minutes later I had 2.5m total depth.
These were the minimum depths across the whole entrance, not at the bar but near the Deben and Knoll Spit buoys.
At that time the Harwich tide gauge read 2.1m. I always refer to this, it is so useful Tide - Harwich Haven Authority
So with the first reading, the shallowest section seems to be around level with Chart Datum. That is similar to what the bar has been in previous years and it may even be lower than that. My friend achieved readings closer to my second result indicating that the depth may be below chart datum.
For the time being, I will look up the HHA tidal depth and use that as the probable minimum depth over the Deben entrance, especially as it is updated every 10 minutes and takes into account the current weather pressure fluctuations. I then add a safety figure below the keel based on the weather conditions.
In previous years we have found that the minimum depth over the bar has been 0.1m or 0.2m below CD, although last year as the old entrance began to narrow we found that later in the summer it had risen to 0.2m above CD. So calculating it to be at CD for the moment is a start, but as mentioned we have only done this twice, so more readings are necessary.
For people coming in two hours before HW they will find the HHA depth (and hopefully the Deben entrance) is well over 2m. I had left at half (rising) tide - over 3 hours before HW. I never come back over the bar much over HW +1hr. Please everyone remember that in a wind with East in it we are like to get some pretty lively conditions in the entrance
Another point about my two readings indicate that by being off line by just a little makes quite a difference, so we believe the entrance 'trench' is quite narrow.
As always please check with John White the Harbourmaster. I am not the expert, he is. Don't copy me, this is just what I do.
John
I left off the figures as I had two readings so don't hold me to them, but after leaving the Deben buoy I had a total depth of 2.1m. I was probably a bit off line to the North because when coming back just a few minutes later I had 2.5m total depth.
These were the minimum depths across the whole entrance, not at the bar but near the Deben and Knoll Spit buoys.
At that time the Harwich tide gauge read 2.1m. I always refer to this, it is so useful Tide - Harwich Haven Authority
So with the first reading, the shallowest section seems to be around level with Chart Datum. That is similar to what the bar has been in previous years and it may even be lower than that. My friend achieved readings closer to my second result indicating that the depth may be below chart datum.
For the time being, I will look up the HHA tidal depth and use that as the probable minimum depth over the Deben entrance, especially as it is updated every 10 minutes and takes into account the current weather pressure fluctuations. I then add a safety figure below the keel based on the weather conditions.
In previous years we have found that the minimum depth over the bar has been 0.1m or 0.2m below CD, although last year as the old entrance began to narrow we found that later in the summer it had risen to 0.2m above CD. So calculating it to be at CD for the moment is a start, but as mentioned we have only done this twice, so more readings are necessary.
For people coming in two hours before HW they will find the HHA depth (and hopefully the Deben entrance) is well over 2m. I had left at half (rising) tide - over 3 hours before HW. I never come back over the bar much over HW +1hr. Please everyone remember that in a wind with East in it we are like to get some pretty lively conditions in the entrance
Another point about my two readings indicate that by being off line by just a little makes quite a difference, so we believe the entrance 'trench' is quite narrow.
As always please check with John White the Harbourmaster. I am not the expert, he is. Don't copy me, this is just what I do.
John
Colvic Watson
Well-known member
Went into the Ore entrance at the weekend 2.5 hours before beep HW.
Interesting, lots of water at the bar, fine after the starboard hand for a while then we ran aground. Absolutely stationary. No way we’re we shifting forward but because it’s shingle and not mud we managed to reverse off. Beware that you need to move to starboard before reaching the tip of the shingle spit, much more water there. The trouble is you need to hug the port side until then. Not fun but no harm done. We’re a long keel, with an exposed rudder, it might have been different.
Interesting, lots of water at the bar, fine after the starboard hand for a while then we ran aground. Absolutely stationary. No way we’re we shifting forward but because it’s shingle and not mud we managed to reverse off. Beware that you need to move to starboard before reaching the tip of the shingle spit, much more water there. The trouble is you need to hug the port side until then. Not fun but no harm done. We’re a long keel, with an exposed rudder, it might have been different.
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Poecheng
Well-known member
Hi CW,
We are due to go in this coming weekend (been in many times before) and just trying to understand your very helpful post.
Did you go aground when going directly from Oxley PHB to Weir SHB?
Colvic Watson
Well-known member
Hi, I’ve corrected my original post!
We came in past the port and left the starboard a little distance away - about a biscuit toss - as per east coast pilot. Turning to starboard we hugged the beach. We have transducers on port and starboard sides of our ridiculously wide hull - a legacy of an old fish finder not because we like to ditch crawl
Anyway there was more water on the port side until we got quite close to the beach. We started edging away toward mid stream but about 100m shy of the exposed tip of the spit we ran aground. We draw 1.5 meters with a sloping long keel, so running aground is never traumatic. I was really surprised though. On the east coast pilot it was about a smidge south of the 4.3m reading. Clearly that little bulge on the west beach sticks out quite a bit. Next time we’ll move to the centre where it says 2.8m. As soon as we reversed and carried on we were quickly in deepish water.
It was a small neep tide and we were just past half flood. Don’t worry about the bar it was a doddle; we’ve learnt our lesson about the later stages of the entrance. We weren’t prepared for such a swift shallowing.
Poecheng
Well-known member
Many thanks for that - really helpful.Hi, I’ve corrected my original post!
We came in past the port and left the starboard a little distance away - about a biscuit toss - as per east coast pilot. Turning to starboard we hugged the beach. We have transducers on port and starboard sides of our ridiculously wide hull - a legacy of an old fish finder not because we like to ditch crawl
Anyway there was more water on the port side until we got quite close to the beach. We started edging away toward mid stream but about 100m shy of the exposed tip of the spit we ran aground. We draw 1.5 meters with a sloping long keel, so running aground is never traumatic. I was really surprised though. On the east coast pilot it was about a smidge south of the 4.3m reading. Clearly that little bulge on the west beach sticks out quite a bit. Next time we’ll move to the centre where it says 2.8m. As soon as we reversed and carried on we were quickly in deepish water.
It was a small neep tide and we were just past half flood. Don’t worry about the bar it was a doddle; we’ve learnt our lesson about the later stages of the entrance. We weren’t prepared for such a swift shallowing.
