NavList:

   

Reply

Jared,

You have completely missed my point.

The horizontal water movement associated with the tides is correctly
termed the "tidal stream", and specifically _not_ a "current" of any
kind. That was correct usage historically [though if you go all the way
back to the 1850s, this movement was just called "tide" (though still
explicitly not "current") and "stream" meant the fast-moving core of any
horizontal flow]. It remains the correct usage in Britain, Canada and, I
would guess, most of the English-speaking world, even though the
ignorant often speak of "tidal current".

U.S. English is, as so often, different. "Tidal current" has gone from
being a neologism into being the accepted term. Bowditch (1995) and the
NOS glossary both recognize only "tidal current" as U.S. usage, while
also noting the British use of "tidal stream". I _think_ I have seen
earlier U.S. authorities note the common use of "tidal current" while
also acknowledging that "tidal stream" is correct. However, I
immediately cannot place my hand on an example.

So once again, if we are being pedantic, the term is "tidal stream".



As to your "Slack tide and slack current usually do not coincide,
either": As I have pointed out before, the term is "slack water" (and on
that one, U.S. and British usage agree). The phenomenon that, I suspect,
you are meaning by "slack tide" is the moment when the rising tide stops
momentarily before beginning to go down again (or vice versa). If so,
that is the "stand of tide" and not a "slack" of any kind.

But you are right that slack water and the stand of tide do not usually
exactly coincide. They would if the tides were perfect standing waves
(and if there were no freshwater outflows to confuse things). They must
at the heads of inlets (again, if no freshwater flow). But the closer
that the tides get to a perfect progressive wave, the further out of
phase the stream and the vertical movement get, until (as in a
deep-water swell) they are 90 degrees out.


Trevor Kenchington


You wrote:

> Trevor-
>   are defined to be more-or-less steady flows.>
>
>  Currents are steady? I have to disagree. In coastal areas, the currents of
> most concern are often tidal currents, as basins and inlets fill then
> discharge with the rise and fall of the tide. Shinnecock Inlet, Jones Inlet,
> the entire body of Long Island Sound, all are subject to Tidal Currents and
> NOAA even published/es a Tidal Current chart set for mariners, so they can
> figure out the local currents based on the state of the tide. Slack tide and
> slack current usually do not coincide, either.
>
>  Ocean currents may be steady--but not "currents" aren't exclusive to
> bluewater sailors.
>


--
Trevor J. Kenchington PhD                         Gadus@iStar.ca
Gadus Associates,                                 Office(902) 889-9250
R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555

                     Science Serving the Fisheries
                      http://home.istar.ca/~gadus

   

Reply