"Joe" wrote
| Wrong...another lubber I see. The rule of thirds is fo tital stream
| flows .
|
| For height you use the rule of 12.

Don't EVER call this girl a lubber, you farmer! :-)

Rule of thirds works for tide height. In the first two hours it goes down 1/3 of its height.
In the next two hours it goes down 1/3 more and in the last two hours it goes down the last
1/3. (I think.)

Cheers,
Ellen

Ellen MacArthur wrote:

Rule of thirds works for tide height. In the first two hours it goes down 1/3 of its height.
In the next two hours it goes down 1/3 more and in the last two hours it goes down the last
1/3. (I think.)


Wrong.

Joe

"Joe" wrote |
| Wrong.

Maybe your right, Mr. Farmer (sign of respect (- Explain how the rule of 12 works.
That's probably what I was thinking. The rule of 1/3 maybe is more for photography.

Cheers,
Ellen

"Ellen MacArthur" wrote
| Rule of thirds works for tide height. In the first two hours it goes down 1/3 of its height.
| In the next two hours it goes down 1/3 more and in the last two hours it goes down the last
| 1/3. (I think.)

Oops! That doesn't sound right. Maybe it goes down 1/4 the first two hours and 1/2 the next
two hours and 1/4 the last two hours. Yes, that's it. Makes more sense that way. It goes down
faster in the middle hours.

Cheers,
Ellen

Ellen MacArthur wrote:
"Ellen MacArthur" wrote
| Rule of thirds works for tide height. In the first two hours it goes down 1/3 of its height.
| In the next two hours it goes down 1/3 more and in the last two hours it goes down the last
| 1/3. (I think.)

Oops! That doesn't sound right. Maybe it goes down 1/4 the first two hours and 1/2 the next
two hours and 1/4 the last two hours. Yes, that's it. Makes more sense that way. It goes down
faster in the middle hours.

Bwahahahaha lubber!

Joe

Cheers,
Ellen

"Joe" wrote


| Bwahahahaha lubber!

OK! You got me. Your not a farmer. (blush, I guess I blew my sailing test debut)

Cheers,
Ellen

Ellen MacArthur wrote:

OK! You got me. Your not a farmer. (blush, I guess I blew my sailing
test debut)

For someone that moans about lack of sailing content in what is widely seen
as a virtual yacht club bar (where the patrons also talk about stuff other
than sailing), you have a lot to yet contribute.

The clue is in the 12ths part...

hour change as a fraction of tidal range
1 1/12
2 2/12
3 3/12
4 3/12
5 2/12
6 1/12

Say the tide drops 5" over the first hour. Since you know that that 5" is
one twelfth of the total range, you can calculate that the tide will have
dropped 5"x12 = 60" = 5 feet when it gets to low water. Of course, 5' is a
girly tidal range. Here, it's a proper, manly 5 metres (or more).


--
Capt Scumbalino

"Capt. Scumbalino" wrote

| The clue is in the 12ths part...
|
| hour change as a fraction of tidal range
| 1 1/12
| 2 2/12
| 3 3/12
| 4 3/12
| 5 2/12
| 6 1/12

Thanks for the explanation. So what's the difference between the rule of 12ths
and the rule of thirds. In the rule of thirds the first two hours it goes down 1/4
which is the same as your 3/12th. The second two hours it goes down 1/2 which is the
same as your 6/12th and the third two hours it goes down 1/4 which is the same as
your 3/12th. See I got it right in spite of myself.

Not a lubber, not a lubber, not a lubber... Yippee!

Cheers,
Ellen

Ellen MacArthur wrote:

Thanks for the explanation. So what's the difference between the
rule of 12ths and the rule of thirds. In the rule of thirds the first
two hours it goes down 1/4 which is the same as your 3/12th. The
second two hours it goes down 1/2 which is the same as your 6/12th
and the third two hours it goes down 1/4 which is the same as your
3/12th. See I got it right in spite of myself.

It's based on the pretty-much universal fact that the time for the tide to
change from high to low water, and vice-versa, is pretty close to six hours.
Since we humans deal with time in chunks of one hour, the question we ask
is: "how much does the tide change in one hour?". Since the smallest
fraction is one twelfth, just before and just after slack water, it's
natural to refer to the tidal change during other hours in terms of the same
denominator. One twelfth in the first hour leads us to express the change
during the second as two twelfths, etc.

Also, the larger the time slot, the greater the granularity. Imagine you're
waiting for the tide to rise enough to clear a sandbar. The rule of thirds
would have you waiting in chunks of two hours before you sail. The rule of
12ths would keep you at anchor for chunks of one hour. Of course, plot the
heights on a graph over time, and you can pinpoint your departure time
(rather, the time at which you can safely cross the sandbar) much more
finely.

Whilst your 'rule of thirds' (which, incidentally, isn't exclusive to
photography, but is a general principle used in many forms of visual art)
may be mathematically correct at its junctures, it doesn't fit with how
people think of time (ie, we think in days of 24 hours, not days of 12
bi-hours).


--
Capt Scumbalino

The point I wanted to make you covered. 1 point to Capt
Scumbalino.

If the range of tide is 8 feet, the first hour is 8".

For a six hour cycle, Multiply by twelve to get inches and
divide by 12 to get 1/12.

It is easier to simply check the range of tide and change
the units to inches.


"Capt. Scumbalino" wrote

Ellen MacArthur wrote:

OK! You got me. Your not a farmer. (blush, I guess I blew my sailing
test debut)

For someone that moans about lack of sailing content in what is widely
seen
as a virtual yacht club bar (where the patrons also talk about stuff other
than sailing), you have a lot to yet contribute.

The clue is in the 12ths part...

hour change as a fraction of tidal range
1 1/12
2 2/12
3 3/12
4 3/12
5 2/12
6 1/12

Say the tide drops 5" over the first hour. Since you know that that 5" is
one twelfth of the total range, you can calculate that the tide will have
dropped 5"x12 = 60" = 5 feet when it gets to low water. Of course, 5' is a
girly tidal range. Here, it's a proper, manly 5 metres (or more).


--
Capt Scumbalino