up-tide or up-stream?

[arran]

Reading the discussion on down-tide moorings I'm a little confused about the up-tide/up-stream definitions (and of course down-tide/down-stream)!

It seems to me there are two options:

1. up-stream=up-tide
2. up-stream=up-river

Any ideas on which is the correct usage

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[MedMan]

I can't be certain about this one, but both logic and common usage would suggest that up-stream means going against the flow of water whilst down-stream means going with the flow of water.

In a tidal river the stream at any given time and place will depend upon the relative strength of the flow of freshwater down-river and the tidal flow. Sometimes they will both be flowing outwards, at others the fresh water will be running out whilst the tide is running in. A weak tide against a strong flow of fresh water will only slow down the outward flow whereas a strong tide against a weak flow of fresh water will reverse the flow.

Of course, I could just be going against the flow of popular opinion ....

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[chas]

Technically, up stream is correct as the tidal stream is what flows along - tide just goes up and down.

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[Twister_Ken]

Beg to differ

For me going upstream always means going towards the head of the river; downstream, towards the sea. If I were going from Tilbury to Teddington on the Thames I would be going upstream whatever way the tide was running. Uptide and downtide are completely different things. The French make it easier by referring to amont or aval (to the hill or to the valley)

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[chas]

Re: Beg to differ

And when you are going down river against the stream?

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[Twister_Ken]

Re: Beg to differ

If I were going from Teddington to Tilbury, I would want to do it down tide. But if I were doing it against the tide, I would be going downstream, up tide.

Maybe the etymology of downstream is stream = river. Thus downstream = down river. My Concise Oxford defines downstream (one word) as "the direction in which a stream or river flows." Note, "stream or river", not "tide".


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[chas]

Re: Beg to differ

Ken

From the Admiralty Manual of Seamanship Vol 2 p 502 – Tides and Tidal streams:

“The rising tide is called the flood tide and the falling tide is called the ebb tide, but care should be taken not to confuse these terms with the flood stream and ebb stream: whereas the term ‘tide’ describes a vertical movement of the sea, the term ‘stream’ describes the horizontal movement of the sea caused by a tide.”

And on p 510:

“Harbour Tidal Streams. When a river current meets tidal water the outgoing stream will naturally run longer and stronger than the ingoing stream, especially if the river is swollen after recent rains; such an exceptionally strong outgoing stream is called a freshet.”

The term “weather going stream,” described as a stream flowing against the wind is also used.

And did you know that “The right and left bank of a river assume the observer to be facing its mouth from a position up river”? I didn’t


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