"Alan Adams" wrote in message
...
In message
"Ewan Scott" wrote:

Snip fair discussion.

Rather than nonsense, just a different view.

I know, but you can't have a debate when everyone agrees can you?
I
still don't see how you manage to go slower than the flow of the
water
when going downstream unless you are doing so deliberately or you
are
being blown backwards by the wind.

Honestly, sitting in the Inazone waiting for others to catch up/
play on
waves - and not in any eddy, I was slowly drifting downstream, but
small
twigs etc were floating slowly past at a faster rate. If we turn
sideways to
the current we drift even slower - gives more time to read
approaching
rapids.

I'd find that a bit hard to believe. What will make a difference is
wind/breeze. The twigs may have been going faster than the water
because of
wind, or more likely a head wind was slowing you down. In the absence
of
wind effects, a boat should travel at the same speed as the water.

This is what I think too.


I think the original discussion was over a comment that progress was
slower
downstream. I took that to mean that speed over the water was less
when
going with the current than against it. Thus 2kph current and 4kph
boat
speed = 2kph upstream, but not quite 6 kph downstream. This I find
quite
likely, as there's less incentive to push hard when going downstream.
Also,
in shallow water, bottom drag will be greater going downstream, as
that is
related to speed over the ground.

This also makes sense, but in the context of paddling on the Thames, we
are talking about deep water.

David Kemper
Getting worried because I'm agreeing with people. Oh, the shame.....