If you sail due east, north, west and south over the ground with the
same speed over the ground and there were no current, no leeway or
other "disturbing factors", you would still not end up at your
starting point (unless....). In fact on the northern hemisphere you
would end up in a position due west of your starting point.

(Assuming we are on the northern hemisphere): When you go back west on
a more northern latitude you will get further west than your starting
point, due to the fact that the meridians are closer together closer
to the pole. The north and south-going legs will even out each other,
but not so for the east and west going leg. If you don't believe me
try to plot it on your chart (and remember to use the right (but not
the same) latitude to measure the length of the nautical mile for your
east-going leg and for your west-going leg.

For this reason if would not give much meaning to call the difference
in start and end position current, set or a tidal vector.

Peter S/Y Anicula



"Bart Senior" skrev i en meddelelse
t...
Donal--I'll give the points to you.

The point of this question was as follows.

If you travel a path where all other factors
are constant, and you do not return to your
starting point, something external force is
acting on your boat. That force is called
current, although it could be wind or
anything else--a barnacle on one side of
your bottom. Anything that you can't
explain is attributed to current.

I apologize if the question was too
vague.



Donal wrote

"Bart Senior" wrote

You sail directly East for 14 hours,
then South for 14 hours,
and then West for 14 hours,
and then North again for 14 hours.

Now if you draw a vector between your starting
position and your final position. What would you
call that vector?

A Tidal vector.

Donal