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Jared wrote:

>  Without looking it up, I only recall "seiche" motions from oceanography
> class. When you are walking with a cup of tea and the tea finds a motion
> resonant with the dimensions of the cup, the motion reinforces itself and
> the the tea slops over the side of the cup. This resonant motion reinforcing
> a wave is what I was told is seiche motion.

The seiche is the dying away of that motion. I am not sure what would
cause a resonant reinforcement, since that would need some periodic
force with a period equal to the resonant period of the basin. There
isn't anything in nature to cause to produce such a periodic force
except the tides. They do cause the reinforcement, if the period of the
basin is right (as with the Bay of Fundy), but the term "seiche" isn't
used for amplified tidal oscillations.

> fisherman asking what time slack tide is, when they mean slack current

If we are being pedantic, it can't be "slack current" because "currents"
are defined to be more-or-less steady flows. What goes slack is the
tidal stream but nobody says "slack tidal stream".

The U.S. National Ocean Service tide glossary calls it "slack water",
which was also what Admiral Smyth called it in 1867. The two together
are authoritative enough for me.


Trevor Kenchington



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Trevor J. Kenchington PhD                         Gadus@iStar.ca
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