I'm sorry Thom I don't follow your thought about RMS. How would
geometric mean be related to the time and size of current flow? If the
tide took twice as long to rise and fall, the RMS would be the same but
the actual current would be smaller would it not?

Cheers


Thom Stewart wrote:

Nav,

Why wouldn't you use a RMS relationship if it close to a sine wave?

Ole Thom

Donal wrote:

"Nav" wrote in message
...

Yes, how about that? Care to comment Donal?


Hey, I ain't an expert on these things.

Why don't you tell us what might have caused it.

I have no idea if there was hurricane there or what the tide difference
was? Only you can tell us that.

I've already expressed the sum total of my knowledge on this subject. Ie,
it might have been caused by pressure systems.

If you think that my opinion is stupid, then you should have the courage to
say so.

Why are you being defensive -you were there weren't you?

If you actually know what caused it, then I'd be grateful if you would share
your knowledge with us. After all, this is a "group". Are you are member,
or not?

I can express an opion based on my Nav but I would need to know more
about what the condions were -how different the tides were etc.

Cheers

Nav,

RMS would be .707 of the Sine wave (Or there abouts) The Tide cycle
being 12 hrs. If we round off .707 to 70% times 12 hrs we would get 8.4
hrs. this would represent the straight line, or Max flow time. The
curved section of the sine wave RMS wise would be 30%. Sense we are only
concerned with a 1/2 wave (Tide Run in one direction) it would Be 15% on
the top (Start of the run) and 15% on the end.
1.8 from slack, 8.4 max flow 1.8 to slack
12hrs total.

Over the years, I've found that this describes the tide flow damn close.
As I explained in a previous post, The slack is the problem. It can last
sometimes for over an hour and at time it doesn't even seem to exist but
the hour and 40minutes still holds up pretty well to max low.

So, as the tide runs start to slow down, you have about 1hr3/4 to make
your inlet on the slack.

As I said before; BE EARLY

Ole Thom

i'm sure you are right but it's interesting to explore the possibilities
is it not? I find it more interesting than guns and GWB (for example).

Cheers

Thom Stewart wrote:

Nav,

Don't you think you are overstating the obvious? The Tide is a dynamic
action of water caused by the moon. The height of the Tide and the Tidal
flow are dependent on one another. The location of the rise in the Tide
is determined by the speed of the earths rotation and the revolving of
the moon. The height of the Tide determined by the Phase of the Moon.
The higher the Tide rise the greater the Tidal Flow

I hope this meets with your approval. I'm very sure we all have
overstated what Scott wanted to know about riding the Tide.

Ole Thom
P/S Donal give him the full point. He gave the answer to the moving
tide, making a tide ride possible

"Nav" wrote in message
...


Donal wrote:

"Nav" wrote in message
...

Yes, how about that? Care to comment Donal?


Hey, I ain't an expert on these things.

Why don't you tell us what might have caused it.

I have no idea if there was hurricane there or what the tide difference
was? Only you can tell us that.

I've already expressed the sum total of my knowledge on this subject.
Ie,
it might have been caused by pressure systems.

If you think that my opinion is stupid, then you should have the courage
to
say so.

Why are you being defensive -you were there weren't you?

Perhaps I misunderstood your question - my apologies!

The fact that I was there doesn't help much. I encountered tides that
appeared to be an hour early. However, if the current was also *stronger*
than forecast, then it is possible that the tide may only have been 1/2 an
hour early. Everything about the trip suggested that the tide turned an
hour early. I don't think that there was a major difference in current.



If you actually know what caused it, then I'd be grateful if you would
share
your knowledge with us. After all, this is a "group". Are you are
member,
or not?

I can express an opion based on my Nav but I would need to know more
about what the condions were -how different the tides were etc.

As stated, I'm fairly sure that the only noticeable difference was that the
tide was early.

After the Cap De la Hague we aimed for about five miles offshore - where we
expected to find about 3 kts behind us. When we discovered that we had 2
kts against us we headed back inshore(where there would be less contrary
tide). As we are familiar with the area, we didn't cough keep an accurate
log.


Regards


Donal
--

Nav,

Guns and "W" Spare me.
You're absolutely right!

Ole Thom

Thom Stewart wrote:

Nav,

Guns and "W" Spare me.
You're absolutely right!


LOL

Don't tell that to Doug!

Cheers

"Peter S/Y Anicula" wrote in message
...
The moon are a lot closer than the sun. Therefore the gravitational
force of the moon varies more over the earth's surface. It is the
variation in the gravitational force and not the force in itself that
creates the tides.

The moons pull on a water-molecule directly under the moon is larger
than
on a molecule on the far side of the earth, actually it is larger than
"the average pull on the whole earth", and here the moon pulls away
from the earth.
On the far side of the earth (seen from the moon) the gravitation from
the moon is less than average and at this point the moon pulls toward
the earth.

On the far side the tide is "high", ... just the same as at the near side.
If the moon's gravity was pulling the water, then you would expect LW to be
opposite the moon.


In the middle (when the moon is in the horizon) the moons
pulls with the same as on the earth as a whole, and there is no
vertical component, so here the water-molecule is "unaffected" by the
moon.

Wrong! This is when LW occurs. By definition, LW is lower than the
average sea level. Therefore, there must be a force that is dragging it
down.


Regards


Donal
--

"Martin Baxter" wrote in message
...
Donal wrote:
"Thom Stewart" wrote in message
...

Marty,

Right you are! Tell Donal to mark you up for One Point.

The Tides use the Moon Calender:^)
That is also the reason that Tide rides are possible.


I'm afraid that I can only award Marty 0.75 of a point.

I'm about to dissappear for a couple of days, so I'll explain when I get
back.

[hint] The sun has a much greater gravitational effect on the Earth
than
the moon. So why does the moon seem to have a greater impact on the
tides?

Well duh! Remember F=G*(m'*m")/(d^2),

Emmm... Huh?

What the hell does that mean in English?

d is very much smaller in the earth moon case than the sun earth case.
IOW, it's because the moon is closer.

Don't tell me! "d" stands for "distance"???


Give my point to Joe, he needs all the help he can get. ;-o

You haven't earned a point - yet! Joe will just have to wait.


Regards


Donal
--

Donal wrote:
So why does the moon seem to have a greater impact on the

tides?

Well duh! Remember F=G*(m'*m")/(d^2),


Emmm... Huh?

What the hell does that mean in English?

Did you not take physics in school? Look up Newton's Law of Gravitation.


d is very much smaller in the earth moon case than the sun earth case.
IOW, it's because the moon is closer.


Don't tell me! "d" stands for "distance"???

Ok, I won't.

Cheers
Marty