Deben Entrance Update

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ditchcrawler

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Info from John White's talk on Sunday.As reported red West Knoll Buoy has been moved about 140m WSW due to the encroachment of the east shingle bank.Green Mid Knoll remains on station but may be moved.Min depth over bar at present after red is 0.8m at LWS.The water is deeper near to the rock bank on the west shore due to scarifying by tide,but the rocks are starting to collapse into the water due to this action.The course is 323deg true from Haven Buoy to West Knoll and then 340deg true from West Knoll to Mid Knoll.John warned of the cross tide effect in both directions due to the shape of the entrance and this is more significant on the ebb.Keep a look out for the chart on www.eastcoastrivers.com
This comes with the usual caveat that no responsibility is attached to this infomation and all skippers are responsible for their own safe navigation(sorry about that but you know how it is nowadays)
 
ditchcrawler said:
Info from John White's talk on Sunday.As reported red West Knoll Buoy has been moved about 140m WSW due to the encroachment of the east shingle bank.Green Mid Knoll remains on station but may be moved.Min depth over bar at present after red is 0.8m at LWS.The water is deeper near to the rock bank on the west shore due to scarifying by tide,but the rocks are starting to collapse into the water due to this action.The course is 323deg true from Haven Buoy to West Knoll and then 340deg true from West Knoll to Mid Knoll.John warned of the cross tide effect in both directions due to the shape of the entrance and this is more significant on the ebb.Keep a look out for the chart on www.eastcoastrivers.com
This comes with the usual caveat that no responsibility is attached to this infomation and all skippers are responsible for their own safe navigation(sorry about that but you know how it is nowadays)
Click to expand...

Thanks
the rocks were a Great Idea then :rolleyes:
 
Thanks for this - sounds better than I'd feared from early reports. Eversons should be launching me next week (with shiny new rigging from Mike V) so will have a tentative first foray out over Easter with luck.
 
As Ditchcrawler has suggested, the best place to find info re both the Deben and Ore entrances is on eastcoastrivers.com
Chris Woods has published the new position of the West Knoll buoy on the website; this will soon be followed by a chartlet and possibly aerial photos.
Take a look at the eastcoastrivers.com forum for the very latest news on the entrances and how the data has been gathered.
The Oxley and Weir buoys will almost certainly be laid in the same positions as last season because there does not appear to have been much change at Shingle Street.
 
Anyone considering crossing the Deben bar before the chartlet is published for 2010 may find this account of interest.

I was due to launch at Larkmans (just below Melton Bridge) on 30th March. The weather forecasts were all over the place, varying from Northerlies over 30kn to Southerlies of 12kn. The most common forecast for the probable time of crossing the bar at 1442 (2 hours after HW on the bar) was 15 to 18kn from the South East. Against one of the biggest ebbs of the year that was bound to cause a rough crossing but my calculations indicated there should be enough water.

Using Reed’s Walton on the Naze tides (4.4m) and the Woodbridge Haven corrections (-0.5m HWS and +0.1m at LWS) the graph indicated a minimum depth above chart datum of 2.7m at HW Woodbridge Haven +2hrs. At a recent talk the harbour master is reported as saying that there was 0.8m minimum depth above chart datum on the bar and that the shallowest water was just after the recently relocated red buoy. I therefore estimated there should be a minimum depth of 3.5m which would be enough for my 1.9m draft with a decent safety margin.

I have been crossing the bar for at least 20 years and would have preferred not to do it with such a big ebb and a fresh SE wind. However, the forecast for the next few days was much worse and there was a distinct possibility of getting neaped in the Tide Mill marina if I went in there. As I passed the Marina entrance at 13.18 (HW Woodbridge) the wind at was SE 12 to 15Kn as predicted by the more optimistic forecasts. Another boat – who only drew about 1.4m – had launched just before me and was going to go straight out so I decided to follow. Inevitably, once we had passed the point of no return to the Marina the wind got up to about 25kn, occasionally gusting to 30kn. The wind blowing straight up the river seemed to hold the tide up for a while but by the time we got to the ferry it was hoovering out. I arrived at the green buoy exactly 2hrs after HW. The bar didn’t look too bad from just before the green buoy but the boat in front seemed to be swept some distance to the north of the red buoy and was bouncing around a lot. I soon found out why. The water was smooth for the first half of the distance between the green and red but after that it was rougher than I have ever seen it. The bows went under about every third wave and my intention of taking pictures disappeared as I do not have an underwater camera. However, I was not worried as the depth stayed steadily at around 3.6m until about 2 boat lengths from the red buoy when it fell to 3.4m. After a wide rounding of the green buoy I had kept plenty of power on and stayed exactly on track, passing the red buoy about half a boat length off. I relaxed as it went past and then to my horror the echo sounder went down to 2.4m – far from enough in those waves. That reading was only momentary - it immediately went back up to 4m +.

The report of the harbour master’s talk mentions that the shallowest point is just after the red buoy. I had assumed that meant on the way in but in my case it was just after on the way out. The low reading may have been at the bottom of a wave but the reading had held steady in the previous waves which were so short that the boat was pitching but not really bodily going up and down much. Even if it was caused by a wave the depth to seaward of the red buoy is very shallow and I suggest others use caution in that area until the chartlet is published.
 
Excellent account Peter, and reminds us why the entrance has a reputation. Pleased you made it through OK, pity about the underwater shots....
 
Yes - Morzen just made the first bar crossing of the season today in perfect conditions.

Usual health warnings apply to my observations but following is what we found heading out on a rising tide (LW Bar was around 13:45) in flat conditions with very high atmospheric pressure at around LW+1:50

15:25 Mid Knolls (G) 3.0M depth
15:30 Halfway between Mid & West Knolls bottom fairly flat at around 2.7M depth
15:34 Least water around 50-100M inside W Knolls at 2.1M depth, then shelves into deeper water fast
15:35 West Knolls (r) 5.3M depth and increasing

Based on my quick calculations this equates to roughly +0.4M least water at LAT. The shallow reading recorded by Peter R must have been an anomaly, possibly caused by thick sediment swirling about in the rough water. Less depth than last year but otherwise straightforward entrance following the usual recommended approach.

Hope this helps.
 
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