Anyone ever measured the tidal flow in Orwell and Stour?

[fredrussell]

Just curious really. My log is bust so I’ve never known. My charts are on the boat but I have a feeling that the tidal diamonds only go as far in as harbour mouth.

 

[johnalison]

It has never occurred to me to think about it. The current in rivers is usually fairly predictable, being stronger on the outside of bends, for example. In Harwich the stream can be strong as it runs over the shallows by the Guard and inside the breakwater. Keeping close to the town side can gain or lose time as you pass the Stour as the stream turns into that river there.

 

[John 32i]

Some information on HHA website, although it only covers the bottom of the Orwell

https://hha.co.uk/wp-content/uploads/2017/10/HHA-Tidal-Maps-All-NEW.pdf

It seemed pretty strong when we decided to swim off the back of the boat near SYH recently :ambivalence:

 

[Leighb]

Some information on HHA website, although it only covers the bottom of the Orwell

https://hha.co.uk/wp-content/uploads/2017/10/HHA-Tidal-Maps-All-NEW.pdf

It seemed pretty strong when we decided to swim off the back of the boat near SYH recently :ambivalence:

it would be, you were on the outside of the bend.
Racing keelboats in the rivers for 15 years or so we got very aware of the tidal flows and how to benefit from them without, hopefully, going aground too often. The flow can vary dramatically between different sides of the river even on straight bits as the deep water where the flow is strongest isn’t always in the centre.
In some places the flow can be opposite around the turn of the tide and it can make a huge difference, a case in point is in the Orwell between the No 6 buoy and Woolverstone. The tide starts to ebb on the South side of the channel around 1 hour before HW when it is still flooding in the deep water and on the North side. On the flood there is a strong back eddy just above Collimer point, etc. Overall rates in the Stour are greater than in the Orwell, perhaps one and a half times or more greater.
hope this is useful.

 

[Corribee Boy]

The general, if unscientific, consensus at Wrabness is that current speed has increased over the years, perhaps because the dredging in the harbour allows more flow. I've never really quantified is as it's so variable.

I certainly can't swim or row against the current as easily as fifty years ago!

 

[Habebty]

I don't have any evidence but the flows seem to have changed on the Orwell in the last two years, there almost seems to be a "stand" at half ebb but then speeds up again, or I could be imagining it Perhaps the dredging has changed the eddy pattern?