Ellen MacArthur wrote:
"Jeff" wrote
(lots of things that don't matter so I deleted them)

I you have any intention of understanding how boats work, or how to do
basic navigation, you will have to learn this stuff.


THIS is what matters and this is what happened in my question.
Your just being thick on purpose. Your wrong and I can prove it with an example.

If I'm being thick (and its happened once or twice before) I'm
certainly not doing it on purpose.


In irons and the wind is pushing you backwards at 2 miles an hour over the bottom.
The current is going the same direction over the ground and at the same speed. 2 mph!
Your going backwards over the ground at 4 mph. Not through the water.
The boat has NO freaking motion through the water and the rudder won't work.

Hello?! If the boat is moving 4 mph over ground, but the current is
only 2 mph, then the boat must be moving 2 mph through the water!
Thus the rudder works.

I knew you'd come around to my way of thinking.

Duh! Forget about looking at the land. There doesn't have to be any land in sight
and you're still dead in the water.

Consider this: assuming the current and the wind have different
strengths (which is the original question) if you get into irons you
will start to slow down. Then you will be dead in the water. Then
you will start to go backwards. at this point your rudder works
again. There is no magic that says if there's a current you can't go
backwards through the water.

Consider also: you've been plopped in the ocean with no position
revealing instruments, but you do have speed and wind gauges. You
sail for some time and then get rescued. Your rescuers ask if you
encountered any current. What can you tell them?

Enough!

never!

"Jeff" wrote |
Hello?! If the boat is moving 4 mph over ground, but the current is
| only 2 mph, then the boat must be moving 2 mph through the water!
| Thus the rudder works.

Well, it doesn't work very good. :-O~

| Consider also: you've been plopped in the ocean with no position
| revealing instruments, but you do have speed and wind gauges. You
| sail for some time and then get rescued. Your rescuers ask if you
| encountered any current. What can you tell them?

Nothing but I can tell them if my rudder worked or not. If there's wind
but no current then it will work in irons because the boat goes backwards.
Look at it this way. The rudder feels a current going by it. (if it could feel).
How fast the current goes past land doesn't matter. Only what matters
is current passing the rudder. If the wind is pushing you back at the same
speed the current's going back the rudder feels no current. Oh, and it's
the same for trying to back the sail by hand. Even if the wind's blowing
10 mph if you're pushed backwards at 10 mph the sail won't feel any wind.
It'll think it's calm out.

Cheers,
Ellen

"Ellen MacArthur" wrote in
message
reenews.ne
t...
Oh, and it's
the same for trying to back the sail by hand. Even if the
wind's blowing
10 mph if you're pushed backwards at 10 mph the sail won't
feel any wind.
It'll think it's calm out.


WTF ?

Ellen MacArthur wrote:
"Jeff" wrote |
Hello?! If the boat is moving 4 mph over ground, but the current is
| only 2 mph, then the boat must be moving 2 mph through the water!
| Thus the rudder works.

Well, it doesn't work very good. :-O~

| Consider also: you've been plopped in the ocean with no position
| revealing instruments, but you do have speed and wind gauges. You
| sail for some time and then get rescued. Your rescuers ask if you
| encountered any current. What can you tell them?

Nothing but I can tell them if my rudder worked or not. If there's wind
but no current then it will work in irons because the boat goes backwards.
Look at it this way. The rudder feels a current going by it. (if it could feel).

NO NO NO! This is your mistake. The rudder does not feel the current
because the boat and the rudder are always being pushed by the
current. If the boat were anchored, then it could feel the current.
Drifting free, there is no way to know there is a current. There is
no observable affect.

Another analogy: if you're flying on a plane, at a steady speed, do
you feel the chair pushing you at 500 mph? In one of Galileo's works
on "relativity" he asked if a fly in a cabin on a boat would be
affected by the boat's forward motion - would it fly any differently?

This is all the same thing. When the medium in/on which you're
traveling is in constant motion, its very hard to detect that motion.


How fast the current goes past land doesn't matter. Only what matters
is current passing the rudder. If the wind is pushing you back at the same
speed the current's going back the rudder feels no current.

Again, NO. The current is already pushing you back at the speed of
the current. This is unobservable to you, except that it alters the
perceived wind. If the wind also pushes you back that will be
"through the water" and you will sense that as sternway.

Oh, and it's
the same for trying to back the sail by hand. Even if the wind's blowing
10 mph if you're pushed backwards at 10 mph the sail won't feel any wind.
It'll think it's calm out.

As I said, if the current is the same strength as the true wind (and
going in the same direction) it will feel like you're becalmed. In
fact, it is indistinguishable from being becalmed. But this only hold
when the wind and current are the same. In general, you subtract
(in a vector way) the current from the true wind and you have the
observable wind.

Jeff, I think you need to draw her a picture, in crayon.

Scotty


"Jeff" wrote in message
. ..
Ellen MacArthur wrote:
"Jeff" wrote |
Hello?! If the boat is moving 4 mph over ground, but
the current is
| only 2 mph, then the boat must be moving 2 mph through
the water!
| Thus the rudder works.

Well, it doesn't work very good. :-O~

| Consider also: you've been plopped in the ocean with
no position
| revealing instruments, but you do have speed and wind
gauges. You
| sail for some time and then get rescued. Your
rescuers ask if you
| encountered any current. What can you tell them?

Nothing but I can tell them if my rudder worked or
not. If there's wind
but no current then it will work in irons because the
boat goes backwards.
Look at it this way. The rudder feels a current going by
it. (if it could feel).

NO NO NO! This is your mistake. The rudder does not feel
the current
because the boat and the rudder are always being pushed
by the
current. If the boat were anchored, then it could feel
the current.
Drifting free, there is no way to know there is a current.
There is
no observable affect.

Another analogy: if you're flying on a plane, at a steady
speed, do
you feel the chair pushing you at 500 mph? In one of
Galileo's works
on "relativity" he asked if a fly in a cabin on a boat
would be
affected by the boat's forward motion - would it fly any
differently?

This is all the same thing. When the medium in/on which
you're
traveling is in constant motion, its very hard to detect
that motion.


How fast the current goes past land doesn't matter. Only
what matters
is current passing the rudder. If the wind is pushing
you back at the same
speed the current's going back the rudder feels no
current.

Again, NO. The current is already pushing you back at the
speed of
the current. This is unobservable to you, except that it
alters the
perceived wind. If the wind also pushes you back that
will be
"through the water" and you will sense that as sternway.

Oh, and it's
the same for trying to back the sail by hand. Even if
the wind's blowing
10 mph if you're pushed backwards at 10 mph the sail
won't feel any wind.
It'll think it's calm out.

As I said, if the current is the same strength as the true
wind (and
going in the same direction) it will feel like you're
becalmed. In
fact, it is indistinguishable from being becalmed. But
this only hold
when the wind and current are the same. In general, you
subtract
(in a vector way) the current from the true wind and you
have the
observable wind.