Deben river entrance April 27th 2021 spring low tide 0.05m above datum photos and video

[Johnah]

Hi All,

In case you have missed these in the other thread, here are the Deben entrance photos and video at almost chart datum.

The Harwich tide gauge was reading 0.05m which is about as low as it will get for a while.

John

 

[Bigplumbs]

Well done very informative as ever. Now all we need is the weather to warm up and we can get out in our boats more

 

[Johnah]

Thanks BP.

Here's another (plan view) photo of the Deben bar at LWS - 0.05m Harwich.

 

[PeterWright]

Hi John,

Another brilliant video. We see none of this coming and going at half tide plus and my memories of sitting on the shingle at the Ferry 55 years ago are not altogether helpful nowadays so I find your videos and photos most informative.

Thank you,

Peter.

 

[miles from the sea]

This is very helpful - looks like a course to the south west of the direct line between woobridge haven and west knoll might be favourite at the moment

 

[Johnah]

Thanks Peter and MRTS, it is changing all the time but at least we have an idea of what it there at the moment.

John White kindly took me out in his boat today at low water to measure the minimum depth at the Bar. I was intrigued to know, looking at the breaking water on the photo above, what the depth below CD actually is.

He showed me that near the Martello Tower there is a shallow section to be aware of, but the shallowest part is at the bar.

Armed with the latest technical equipment, a marked stick, the depth at the bar at 9.40 am was found to be 0.9m.

The reading above CD at Harwich on the HHA website read 0.74m at that time, so the bar is just below CD at approx 0.1m.

Most of us don't ever get close to hitting the bar coming and going a couple of hours before HW, but there are sometimes when we need to get out over the bar (on a rising tide) as early as possible and this information can be handy.

Many thanks to John White for his assistance today.

John

 

[PeterWright]

Thanks, John, that's another key bit of info to store away. When we cross it's often with the intention of going into the Tidemill harbour so we try for half tide in order to have water over the cill on arrival in Woodbridge although at 6 foot draft, that's not guaranteed at neaps. Equally as we can rarely leave the Tide Mill much before HW, we usually go out on the ebb but before half tide. I don't like to even think of the consequence of getting it wrong on the ebb..

Peter.

 

[Flames]

Thank you Johnah and John White for the brilliant information on the bar height/ depth of water.
As a half a dozen times a year visitor to the Deban I can now work out times to enter or leave using your valuable data. Taking into account the draft of my motor boat and depth of the swell I can see that 2 metres on the HHA tidal prediction charts should give me 2.15 metre at the bar.
Providing the Predictions, the live data and wave heights all remain similar I can by referring to the HHA website very helpfully have the times of the window for an in or out passage.
Many thanks again for your time and effort.
Best regards.

 

[Johnah]

Thanks Peter, look forward to seeing you in the Deben.

Hi Flames,

Yes I refer to the HHA live data tide information before crossing the bar, but take the depth at the bar as no more than the depth that the Harwich gauge reads above CD, to allow for a bit of clearance.

We measured it yesterday but it may have changed today. John White said the depth had changed slightly since the buoys were positioned.

Tide - Harwich Haven Authority

Also, if it's a bit rough then a boat might sit down in a trough, so best not cut it too fine!

There is not much wiggle room this year so stay close to the buoys.


John

 

[Johnah]

I tried out the Deben bar for real tonight (6th May) leaving from the Ferry in my fin keel Moody 31. There was only a slight NW offshore breeze and virtually no swell.

Must say it felt a bit strange with the channel being relatively narrow, and it was quite shallow when passing the Martello Tower. John White the Harbour Master had explained that this ridge went right across, but I think I was too close to the shore when passing over it.

The bar itself was almost the easy bit but worked back (according to HHA tide gauge) to a level of Chart Datum -0.1m, which is close to the measurements taken last week.

Coming back into the river was fine. I kept closer to mid channel at the Martello Tower where it was a bit deeper than at the bar.

John

 

[PeterR]

Many thanks for the drone video, As always it is very useful. I attach a video I made of my exit from the river on the 28th May. The calculated depth of water on the bar at LAT was much as you and John describe. (somewhere between nothing and 0.1m). I recorded 3.0 metres 1 hour 26 minutes after local HW when the Harwich guage showed a height of tide as 3.0m and the Approach guage showed 2.9m. Interestingly I only recorded 3.2 metres metres passing over the ridge abeam the Martello Tower which was less than I was expecting. Perhaps it has got shallower there after the storms in early May or perhaps I was not in the deepest part of the channel. Either way, for boats on the way out of the river it provides a guide as to what to expect on the bar itself and the chance to bail out if you don't like what you see.

 

[Johnah]

Interesting numbers Peter and it does show that the Harwich tide gauge pretty well corresponds with the height of water over the bar. Agree that the new ridge by the Martello Tower is just a bit lower than the bar itself.

I have been in and out of the Deben several times now and the depths seem to correlate well to the HHA web page depths for Harwich, but things can change.

You make a good point that the Martello Tower 'ridge' gives us a good chance to bail out if it looks marginal when leaving the Deben.

Did a bar depth check a few weeks ago by leaving the Deben when the Horse sand was just covered on a rising tide. Some boat owners use this as a gauge. When the last seagull was left standing with wet feet on the Horse sand, I gingerly motored from the Ferry to find the bar was measured at 1.9m, and closely confirmed by the HHA tide gauge. That was four hours before HW.

Don't recommend anyone tries it this early and it was flat calm. I only had 0.3m under the keel.

As far as coming back over the bar on a falling tide I don't normally come in more than an hour after HW. Interestingly at about 1/2 hour after HW, the water is still coming into the river up to Felixstowe Ferry.

John