push vs pull vis a vis rudders
 

steeeeeeeeeeeeeeeeeeeeeeve???

Sure you can create a vacuum in water,

??? using maybe that age-old force in nature called "suction" maybe?

try again.

push vs pull vis a vis rudders
 

think it through, steve. think it through.

no it doesn't. It doesn't matter that they are attached. The rudder
will have an effect if there is water flowing over it.

so, which way does the stern move if the rudder is to port?

push vs pull vis a vis rudders
 

Of course that doesn't mean the rudder has no effect at all, which is
what you claimed.

you can't see it, you can't measure it, you can't detect that it is there at
all, but it still exists? How is that?

And which way does the stern move with the rudder one way or the other?


Steve

push vs pull vis a vis rudders
 

How
about an explanation of those phenomena for a numerate old
thickie?

each blade the prop (in reverse) pushes water forward towards the bow of the
boat (also sides, but ignore that). Because "water flows downhill" water fills
in behind each blade as it pushed water forward

(note, if you watch an underwater prop turning in a stationary position, you
will see the level of the water surface fall behind the prop and rise forward
of the prop)

Now, the water that fills in behind the blades comes from whereever there is
water "uphill" of the blade. This is not just behind the prop, but also to the
sides and top and bottom, in more or less a hemisphere (an over simplification.
water actually comes from the "high pressure" side of the blade, the side
towards which the water is pushed.)

The flow "through the prop circle" hs the greatest velocity, with "all that
water" aft just waiting for its chance to "roll down hill". the greater the
distance from the prop, the slower the speed of the water rolling down hill
(lots of water available so it doesn't roll very fast. The speed at which the
water rolls towards the prop is inversely proportional to 4/3rd the distance
cubed (volume of sphere) is all aimed at the center of the prop.

People "think" the water flow towards the prop is straight at the prop, but it
isn't. it is from all edges of the hemisphere aft of the prop. Left, right,
up down, back. all edges.

push vs pull vis a vis rudders
 

jim, airspeed over a wing does not have to faster than airspeed below a wing
for a wing to have lift. "bernoulli" sounds conventiently scientific to
explain lift, but it ain't real.

Of course I won't make that mistake. What made you think I would?
I repeat the relevant part of my post:

"Any pressure change in a freely flowing fluid will be matched to
a change in local fluid speed (barring supersonics, flow
breakaway, and the trivial effects of surface viscosity) to
conserve energy. This is (presumably) the 'bernouili' bit you
claim is often erroneous."

I said this in response to your statement that pressure change
does not have to be related to a speed change in the
circumstances we're talking about. This seemed to me to violate
the laws of conservation of energy. It was you who called
Bernoulli into it, bless his cotton socks. I quote from your
post:

"water speed does not have to be equal or greater or less. This
can be a bit
confusing because "bernoulli" is often -- though erroneously --
given as the
reason sails/wings have "lift"."

You were here responding to my assumption that if there's a
(mean) pressure differential over the rudder, than there will be
an allied mean change in fluid speed. Just like an airplane wing
creating lift. The fluid speed on the low pressure side will be
faster (caveats for supersonic flow etc - we are talking boats).
I hope you don't disagree with that.

JimB

push vs pull vis a vis rudders
 

he is a yo-yo.

candidly, when I first saw his post and noted his email address, I figured some
yo-yo hijacked his address. He claimed professional expertise in fluid flow,
but his website make no mention of such, though it does promote his "expertise"
in control systems for things such as MRI's.

similar to what the good professor at MIT observed with
his fan.

what the "good professor at MIT observed" was that starting
with an an empty
tube there was a tiny movement until the tube filled.


I seem to remember you damned the professor for using a metaphor
. . .

JimB

push vs pull vis a vis rudders
 

On 30 Mar 2004 19:53:18 GMT, (JAXAshby) wrote:

think it through, steve. think it through.

no it doesn't. It doesn't matter that they are attached. The rudder
will have an effect if there is water flowing over it.

so, which way does the stern move if the rudder is to port?

forward or reverse? rh prop or lh prop? how much prop walk?

Steve

push vs pull vis a vis rudders
 

On 30 Mar 2004 19:54:48 GMT, (JAXAshby) wrote:

Of course that doesn't mean the rudder has no effect at all, which is
what you claimed.

you can't see it, you can't measure it, you can't detect that it is there at
all, but it still exists? How is that?

You can measure it. You can detect if it's there or not. All you need
are stress sensors on the rudder post to measure what the rudder is
doing.

And which way does the stern move with the rudder one way or the other?

That's a big "it depends". Of course that doesn't mean the rudder has
no effect. The same thing can be said for the engine in forward. I.e.,
you can't predict which way the boat will turn when you turn the rudder
one way or another if other factors, like the wind, have a greater
effect than the rudder.

Steve

push vs pull vis a vis rudders
 

On Tue, 30 Mar 2004 08:04:41 -0700, Keith Hughes
wrote:



Steven Shelikoff wrote:

That's ok. Fluid on the pressure side of the prop is nowhere near
laminar either and will in fact be totally non-uniform around the
rudder. Yet the rudder still has an effect on the boat's direction.


No, it's not laminar, it is unidirectional along one axis.

Actually, it's not that either.

Unidirectional flow can be diverted creating a thrust vector, unlike
the non-unidirectional flow on the suction side where the rudder
provides pressure drop instead of redirection/diversion. That's the
difference.

Yes, you can create a thrust vector by diverting non-unidirectional flow
as long as the the sum of the non-unidirectional flow is not 0, which it
is not for the case we are talking about because if it was, the boat
would not move backwards when the engine is put in reverse.

Sure you can create a vacuum in water,

You need to check the definition of vacuum if you believe this.
"Vacuum in water" is an oxymoron.

You're probably thinking of an absolute vacuum. In that case, a "vacuum
in air" is an oxymoron also. But since you mentioned a vacuum in air,
here we must talking about a relative vacuum which is simply an area
where the pressure is lower than another area. That is easily created
in water.

just like in air. The only
difference is that water doesn't change it's volume (as much, but it
does a small amoutn) when the pressure changes.

The *liquid* volume does not change, that's a basic property of
liquids. Their volume is temperature dependent, not pressure

Actually, the liquid volume can change when the pressure changes.
However, it's a minute amount only measurable for drastic pressure
changes. But that's outside the scope of this thread, where we can
treat the liquid volume as constant when the pressure changes.

dependent. If you reduce the pressure, dissolved gases will evolve
(that *is* cavitation) but you now have bubbles suspended in a
liquid, i.e. foam.

That depends on how much you reduce the pressure. Is it your contention
that anytime you reduce the pressure of a liquid by any amount that you
must have cavitation? If so, you are plainly wrong.

There's still a vacuum
though.

Don't think so.

You think wrong ... if we're talking about a relative vacuum and not an
absolute vacuum, which is obvious we are from your previous statement:
"so you can't create a vacuum in water like you do in air." A vacuum in
air is also an oxymoron unless you're *not* talking about an absolute
vacuum.

And you can certainly create a vacuum in water without cavitation.
Cavitation only occurs if the pressure of the water drops below it's
vapor pressure.

Yes, and you would create a vacuum without doing this exactly how?
Fluid is not elastic. Move it from one point too quickly (what you'd
*have* to do to create a local low pressure area) and you will
liberate dissolve gas (even gaseous water) due to the low pressure
and/or high temperature created by the shear. Water doesn't stretch.

But it does flow from higher pressure areas to lower pressure areas.
The lower pressure areas are the vacuum in this case, just like air.
And it does not have to cavitate in the areas under lower pressure.

There's a whole art/science of creating props that work
without cavitation for use with submarines.

Quite so. They do not, however, generate 'pockets of vacuum' in
doing so.

Sure they do. The area in front of the prop blade is at a lower
pressure than the area behind the prop. i.e., one definition of a
vacuum.

You can measure a vacuum in water yourself if you want. Just put a
vacuum gauge behind a water pump and you will measure the vacuum of the
pump sucking water through it. I have several of them on my boat for
measuring the condition of fuel filters.

Steve

push vs pull vis a vis rudders
 

think it through, steve. think it through.

no it doesn't. It doesn't matter that they are attached. The rudder
will have an effect if there is water flowing over it.

so, which way does the stern move if the rudder is to port?

forward or reverse? rh prop or lh prop? how much prop walk?

reverse (that was the discussion), and your choice (neither affects the
outcome) and your choice (no value affects the outcome).


Steve

push vs pull vis a vis rudders
 

you can't see it, you can't measure it, you can't detect that it is there at
all, but it still exists? How is that?

You can measure it. You can detect if it's there or not. All you need
are stress sensors on the rudder post to measure what the rudder is
doing.

how about the "stress sensors" you have on the steering wheel or tiller. What
are *they* telling you?

push vs pull vis a vis rudders
 

The same thing can be said for the engine in forward. I.e.,
you can't predict which way the boat will turn when you turn the rudder
one way or another

maybe *you* can't predict which way the boat will turn but the rest of the
boating population can.

push vs pull vis a vis rudders
 

schlackoff, don't drink so much before you post. tomorrow you read your post
below and you are going to one embarrassed dude.

you can create a thrust vector by diverting non-unidirectional flow
as long as the the sum of the non-unidirectional flow is not 0, which it
is not for the case we are talking about because if it was, the boat
would not move backwards when the engine is put in reverse.


you tipped a bit more and wrote this:

You're probably thinking of an absolute vacuum. In that case, a "vacuum
in air" is an oxymoron also. But since you mentioned a vacuum in air,
here we must talking about a relative vacuum which is simply an area
where the pressure is lower than another area. That is easily created
in water.


you tipped even more and wrote this embarrassing drivel


Actually, the liquid volume can change when the pressure changes.
However, it's a minute amount only measurable for drastic pressure
changes. But that's outside the scope of this thread, where we can
treat the liquid volume as constant when the pressure changes.

onward you went with this:

That depends on how much you reduce the pressure. Is it your contention
that anytime you reduce the pressure of a liquid by any amount that you
must have cavitation? If so, you are plainly wrong.

you wrote the following which makes no sense at all.


You think wrong ... if we're talking about a relative vacuum and not an
absolute vacuum, which is obvious we are from your previous statement:
"so you can't create a vacuum in water like you do in air." A vacuum in
air is also an oxymoron unless you're *not* talking about an absolute
vacuum.

more confusiong with:

But it does flow from higher pressure areas to lower pressure areas.
The lower pressure areas are the vacuum in this case, just like air.
And it does not have to cavitate in the areas under lower pressure.


huh??

Sure they do. The area in front of the prop blade is at a lower
pressure than the area behind the prop. i.e., one definition of a
vacuum.

You can measure a vacuum in water yourself if you want. Just put a
vacuum gauge behind a water pump and you will measure the vacuum of the
pump sucking water through it. I have several of them on my boat for
measuring the condition of fuel filters.

Steve

push vs pull vis a vis rudders
 

On 31 Mar 2004 00:37:12 GMT, (JAXAshby) wrote:

you can't see it, you can't measure it, you can't detect that it is there at
all, but it still exists? How is that?

You can measure it. You can detect if it's there or not. All you need
are stress sensors on the rudder post to measure what the rudder is
doing.

how about the "stress sensors" you have on the steering wheel or tiller. What
are *they* telling you?

One thing they may not be telling you is the small amount lateral force
generated by a prop in reverse.

Steve

push vs pull vis a vis rudders
 

On 31 Mar 2004 00:38:47 GMT, (JAXAshby) wrote:

The same thing can be said for the engine in forward. I.e.,
you can't predict which way the boat will turn when you turn the rudder
one way or another

maybe *you* can't predict which way the boat will turn but the rest of the
boating population can.

Uh huh. Well, you must not be very experienced if you've never had your
boat turn in the opposite direction from where you had the rudder. Stop
playing in the bathtub and get some real experience.

Steve

push vs pull vis a vis rudders
 

Jox, adults are having a conversation. Come back when you have
something of value to post.

Steve

push vs pull vis a vis rudders
 

yuk yuk. schaloff make a funny.

Jox, adults are having a conversation. Come back when you have
something of value to post.

Steve

push vs pull vis a vis rudders
 

you can't see it, you can't feel it, you can't measure it, but ...

they may not be telling you is the small amount lateral force
generated by a prop in reverse.

sure, schlackoff. sure.

push vs pull vis a vis rudders
 

yeah, sure. rudder right, tranny forward, throttle forward and what happens
.....???


The same thing can be said for the engine in forward. I.e.,
you can't predict which way the boat will turn when you turn the rudder
one way or another

maybe *you* can't predict which way the boat will turn but the rest of the
boating population can.

Uh huh. Well, you must not be very experienced if you've never had your
boat turn in the opposite direction from where you had the rudder. Stop
playing in the bathtub and get some real experience.

Steve

push vs pull vis a vis rudders
 

On 31 Mar 2004 04:43:29 GMT, (JAXAshby) wrote:

yeah, sure. rudder right, tranny forward, throttle forward and what happens
....???

Most times you go right. Sometimes you go left. If you've never gone
left when doing the above, you need some more experience.

Steve

The same thing can be said for the engine in forward. I.e.,
you can't predict which way the boat will turn when you turn the rudder
one way or another

maybe *you* can't predict which way the boat will turn but the rest of the
boating population can.

Uh huh. Well, you must not be very experienced if you've never had your
boat turn in the opposite direction from where you had the rudder. Stop
playing in the bathtub and get some real experience.

Steve

push vs pull vis a vis rudders
 

JAXAshby wrote in message
...

The speed at which the
water rolls towards the prop is inversely proportional to 4/3rd
the distance
cubed (volume of sphere) is all aimed at the center of the
prop.

People "think" the water flow towards the prop is straight at
the prop, but it
isn't. it is from all edges of the hemisphere aft of the prop.
Left, right,
up down, back. all edges.

Lovely. I understand that. A plume with an enormous splay angle
converging into the prop. No need to do the 'rolling downhill
bit' for me.

Some of the plume being interfered with by various obstacles
(such as rudders and hulls).

At this stage you may be interested in the behaviour of my model
of smoking fag ends, bits of card and wire hinges, all mounted up
stream of the heater fan suggested by Derek Rowell.

First, there is a net force on the rudder, primarily exerted in
the direction of the fan.It has little lateral component, but
lots of fore and aft component (Those wire hinges were good for
resolving things). There's strong non-linear flow when the rudder
is deflected, but the net flow is an s bend zig-zagging around
it, going to the fan. Approach speed dropped markedly with
distance from the fan (as you comment - a cube relationship if
there are no constraints)

The rudder kicks hard over when it is allowed to pivot around its
forward vertical axis. Within the limitations of my crude
experiment, this seems to be caused mainly by the net effect of
the fore and aft component of force, not a lateral component.
This explains the rudder kick I've witnessed in astern in some
boats, and probably explains Derek Rowell's observation that the
rudder rotates when allowed to (If I understood his experiment
design right). My thanks to him for suggesting the idea of an
experiment. It's been great fun.

So I can now understand the mechanism whereby there's rudder
kick, but little or no lateral force. And I'm stuck with the
revelation that the yaw effect that my old skipper demonstrated
to me was wind, mirrors, inertia, prop walk and my hero worship.
Ah well.

But now I've got to get rid of those carpet burns before the wife
comes home.

JimB

push vs pull vis a vis rudders
 

JAXAshby wrote in message
...

Referring to Derek Rowell:

candidly, when I first saw his post and noted his email
address, I figured some
yo-yo hijacked his address. He claimed professional expertise
in fluid flow,
but his website make no mention of such, though it does promote
his "expertise"
in control systems for things such as MRI's.

It is sad, though, that you chose to libel him rather than argue
the case. Weakens your credibility.

JimB

push vs pull vis a vis rudders
 

Steven Shelikoff wrote in message
...
On Tue, 30 Mar 2004 08:04:41 -0700, Keith Hughes
wrote:

enormous snip

Sorry to interrupt this thread, but you may remember a little
earlier I said I'd go away and play with fans, bits of card, bits
of wire and smoking fag ends to get my brain around this. The
idea was suggested by a very reasonable post from Derek Rowell.

I'm trying to square Jax's flat 'nada' with rudder kick I've
observed, and an impression that the rudder direction affects
boat yaw when in reverse and not moving,

I fixed a card to a bit of wire which I could bend at various
angles to the card (rudder angle). I then hung the card upstream
of the fan so that it could pivot only along the fore and aft
axis (above the fan) and again so it could pilot only along the
lateral axis, and again so that the rudder could rotate around
the vertical axis of its front post. Smoking fag ends came later,
with a rigid mount. Fan was turned on.

Forces were observed by noting the degree of card deflection
around the relevant hinge. There was a net force on the rudder,
primarily exerted towards the fan. It has little lateral
component, but lots of fore and aft component.

Smoking fag ends showed strong non-linear flow when the rudder
was deflected, but the net flow is an s bend zig-zagging around
the rudder towards the fan and two carpet burns. Smoke speed
dropped markedly with distance away from the fan.

The rudder kicked hard over (either way) when allowed to pivot
around its forward vertical axis. Within the limitations of my
crude experiment, rudder kick is probably caused by the net
effect of the fore and aft component of force, not a lateral
component.

I think this explains the rudder kick I've witnessed in astern in
some boats engaging astern gear, and probably explains Derek
Rowell's observation that the rudder rotates when allowed to (If
I understood his experiment design right).

However, the zig-zagging airflow proves to my satisfaction that
the rudder may not create a net lateral force, so I'm stuck with
the revelation that the yaw effect that my old skipper
demonstrated to me was wind, mirrors, inertia, prop walk and my
hero worship.

Ah well.

But now I've got to get rid of those carpet burns before the wife
comes home.

JimB

push vs pull vis a vis rudders
 

On Wed, 31 Mar 2004 10:20:59 +0100, "JimB"
wrote:


Steven Shelikoff wrote in message
...
On Tue, 30 Mar 2004 08:04:41 -0700, Keith Hughes
wrote:

enormous snip

Sorry to interrupt this thread, but you may remember a little
earlier I said I'd go away and play with fans, bits of card, bits
of wire and smoking fag ends to get my brain around this. The
idea was suggested by a very reasonable post from Derek Rowell.

Just to settle it for myself, once and for all, I just did my own
experiment. I have a fan in the living room. It's about 12" in
diameter. I got a light plastic spatula from the kitchen. I turned the
fan on high and hung the spatula blade in front of the fan free to swing
in all directions while I was controlling the angle of the blade to the
fan. As expected, when I rotate the blade left, the spatula swings
forward and to the left. Rotate right, it swings forward and to the
right.

So I hung the spatula just behind the fan. Lo and behold, the same
thing happens but just a little less. When I rotate the spatula to the
left, there is a noticable *left* motion to the blade... i.e., it's not
only drawn forward into the blade but it also moved to the left from
where it was when the spatula blade was perpendicular to the fan. When
I turn it to the right, the spatula swings to the right.

That proves to my satisfaction that if the rudder is close enough to the
prop, it's direction will have some effect on the motion of the boat
when you throw it in reverse even before the boat starts making sterway.

Steve

push vs pull vis a vis rudders
 

On Wed, 31 Mar 2004 10:20:59 +0100, "JimB"
wrote:
.....
I fixed a card to a bit of wire which I could bend at various
angles to the card (rudder angle). I then hung the card upstream
of the fan so that it could pivot only along the fore and aft
axis (above the fan) and again so it could pilot only along the
lateral axis, and again so that the rudder could rotate around
the vertical axis of its front post. Smoking fag ends came later,
with a rigid mount. Fan was turned on.

Forces were observed by noting the degree of card deflection
around the relevant hinge. There was a net force on the rudder,
primarily exerted towards the fan. It has little lateral
component, but lots of fore and aft component.

Smoking fag ends showed strong non-linear flow when the rudder
was deflected, but the net flow is an s bend zig-zagging around
the rudder towards the fan and two carpet burns. Smoke speed
dropped markedly with distance away from the fan.

The rudder kicked hard over (either way) when allowed to pivot
around its forward vertical axis. Within the limitations of my
crude experiment, rudder kick is probably caused by the net
effect of the fore and aft component of force, not a lateral
component.

I think this explains the rudder kick I've witnessed in astern in
some boats engaging astern gear, and probably explains Derek
Rowell's observation that the rudder rotates when allowed to (If
I understood his experiment design right).

However, the zig-zagging airflow proves to my satisfaction that
the rudder may not create a net lateral force, so I'm stuck with
the revelation that the yaw effect that my old skipper
demonstrated to me was wind, mirrors, inertia, prop walk and my
hero worship.

Ah well.

But now I've got to get rid of those carpet burns before the wife
comes home.

JimB

Asking for explanations from experimental rigs is the royal road to
progress. Congratulations!
Couple of your observations bear talking about.

If a hinge surface is hinged more than about 1/4 aft of its present
leading edge it is unstable in the fluid flow. ('rudder kick')

If a surface *is* hinged about 1/4 from the leading edge, it can
still break into oscillations which are quickly destructive, unless
the mass is balanced closer to the hinge line.

If a FLAT surface is inclined slightly ( 20 degrees) to the fluid
flow, the flow over the 'upper' surface is faster and provides lower
pressure than the flow over the lower surface. The streamlines do not
follow the (flat) surface of the test article (of course!), they kick
up in a smooth curve over the top. This applies to an airfoil flown
upside down too. The streamlines look similar to the streamlines
over a right way up foil, but less efficient and with lower pressure
difference from top/bottom.

It is not necessary for a lump of fluid dividing past the foil to
join up again after it has passed..
When providing lift, the lump of fluid does not join up again, in
fact.

Brian Whatcott

push vs pull vis a vis rudders
 

sherr tells us the more experience he has the more he don't know which way his
boat is gonna go thusly:

yeah, sure. rudder right, tranny forward, throttle forward and what happens
....???

Most times you go right. Sometimes you go left. If you've never gone
left when doing the above, you need some more experience.

push vs pull vis a vis rudders
 

Thanks Jim for taking the time to experiment.

Lovely. I understand that. A plume with an enormous splay angle
converging into the prop. No need to do the 'rolling downhill
bit' for me.

Some of the plume being interfered with by various obstacles
(such as rudders and hulls).

At this stage you may be interested in the behaviour of my model
of smoking fag ends, bits of card and wire hinges, all mounted up
stream of the heater fan suggested by Derek Rowell.

First, there is a net force on the rudder, primarily exerted in
the direction of the fan.It has little lateral component, but
lots of fore and aft component (Those wire hinges were good for
resolving things). There's strong non-linear flow when the rudder
is deflected, but the net flow is an s bend zig-zagging around
it, going to the fan. Approach speed dropped markedly with
distance from the fan (as you comment - a cube relationship if
there are no constraints)

The rudder kicks hard over when it is allowed to pivot around its
forward vertical axis. Within the limitations of my crude
experiment, this seems to be caused mainly by the net effect of
the fore and aft component of force, not a lateral component.
This explains the rudder kick I've witnessed in astern in some
boats, and probably explains Derek Rowell's observation that the
rudder rotates when allowed to (If I understood his experiment
design right). My thanks to him for suggesting the idea of an
experiment. It's been great fun.

So I can now understand the mechanism whereby there's rudder
kick, but little or no lateral force. And I'm stuck with the
revelation that the yaw effect that my old skipper demonstrated
to me was wind, mirrors, inertia, prop walk and my hero worship.
Ah well.

But now I've got to get rid of those carpet burns before the wife
comes home.

JimB

push vs pull vis a vis rudders
 

Jim, I limited time for frauds. in this case rowell lied straight out to us,
saying that professionally he was an expert in fluid flow. Yet, even his own
website drumming up business for his consulting services fails to mention fluid
flow experience, let alone expertise.

He choice of words right from the get go indicated his fraudulant
underpinnings. In the end you reduced himself to arguing that friction in the
rudder bearings were the reason reverse flow showed no effects on lateral
movement of the rudder.

Referring to Derek Rowell:

candidly, when I first saw his post and noted his email
address, I figured some
yo-yo hijacked his address. He claimed professional expertise
in fluid flow,
but his website make no mention of such, though it does promote
his "expertise"
in control systems for things such as MRI's.

It is sad, though, that you chose to libel him rather than argue
the case. Weakens your credibility.

JimB

push vs pull vis a vis rudders
 

sorry about the mistyping.

In the end you reduced himself to arguing that friction in the
rudder bearings were the reason

should be "he reduced himself"

push vs pull vis a vis rudders
 

That's a blatant lie, jaxie, you should be ashamed of yourself. Its one thing
to be stupid, that is your right, one which you exercise quite frequently. But
to lie so blatantly after you libel someone in unconscionable. It was clear
that the last thing you wanted was a professor of mechanical engineering
criticizing you logic, so you chased him away.

Your behavior was tantamount to admitting that you really don't know what you're
talking and were terrified of a rational discussion.



"JAXAshby" wrote in message
...
Jim, I limited time for frauds. in this case rowell lied straight out to us,
saying that professionally he was an expert in fluid flow. Yet, even his own
website drumming up business for his consulting services fails to mention
fluid
flow experience, let alone expertise.

He choice of words right from the get go indicated his fraudulant
underpinnings. In the end you reduced himself to arguing that friction in the
rudder bearings were the reason reverse flow showed no effects on lateral
movement of the rudder.

Referring to Derek Rowell:

candidly, when I first saw his post and noted his email
address, I figured some
yo-yo hijacked his address. He claimed professional expertise
in fluid flow,
but his website make no mention of such, though it does promote
his "expertise"
in control systems for things such as MRI's.

It is sad, though, that you chose to libel him rather than argue
the case. Weakens your credibility.

JimB

push vs pull vis a vis rudders
 

On Wed, 31 Mar 2004 10:20:59 +0100, "JimB"
wrote:


[snip]
I'm trying to square Jax's flat 'nada' with rudder kick I've
observed, and an impression that the rudder direction affects
boat yaw when in reverse and not moving,
[snip]

I have observed the rudder kick in reverse, but only with the boat in
motion. Does yours do this when tied to the dock?

I expect to be able to try this in the next week or so, but because
of the distance from prop to rudder, my reslult won't be directly
applicable.



Rodney Myrvaagnes NYC J36 Gjo/a

"WooWooism lives" Anon grafitto on the base of the Cuttyhunk breakwater light

push vs pull vis a vis rudders
 

jeffies, you know more about fluid flow than he does, and you are weak at it.

That's a blatant lie, jaxie, you should be ashamed of yourself. Its one
thing
to be stupid, that is your right, one which you exercise quite frequently.
But
to lie so blatantly after you libel someone in unconscionable. It was clear
that the last thing you wanted was a professor of mechanical engineering
criticizing you logic, so you chased him away.

Your behavior was tantamount to admitting that you really don't know what
you're
talking and were terrified of a rational discussion.



"JAXAshby" wrote in message
...
Jim, I limited time for frauds. in this case rowell lied straight out to
us,
saying that professionally he was an expert in fluid flow. Yet, even his
own
website drumming up business for his consulting services fails to mention
fluid
flow experience, let alone expertise.

He choice of words right from the get go indicated his fraudulant
underpinnings. In the end you reduced himself to arguing that friction in
the
rudder bearings were the reason reverse flow showed no effects on lateral
movement of the rudder.

Referring to Derek Rowell:

candidly, when I first saw his post and noted his email
address, I figured some
yo-yo hijacked his address. He claimed professional expertise
in fluid flow,
but his website make no mention of such, though it does promote
his "expertise"
in control systems for things such as MRI's.

It is sad, though, that you chose to libel him rather than argue
the case. Weakens your credibility.

JimB

push vs pull vis a vis rudders
 

I have observed the rudder kick in reverse
, but only with the boat in
motion.


if the boat is moving through the water, the rudder can control its direction.

push vs pull vis a vis rudders
 

On 31 Mar 2004 16:22:57 GMT, (JAXAshby) wrote:


yeah, sure. rudder right, tranny forward, throttle forward and what happens
....???

Most times you go right. Sometimes you go left. If you've never gone
left when doing the above, you need some more experience.

sherr tells us the more experience he has the more he don't know which way his
boat is gonna go thusly:

Joxie, say it ain't so! With all your claimed sea experience you've
never had the boat turn in a different direction than where you had the
rudder pointed? Oh, that's right. You're just a hired hand with no
helm experience. If you had any time at the helm in poor conditions
you'd know just how foolish you're looking right about now.

Steve

push vs pull vis a vis rudders
 

On 31 Mar 2004 16:22:57 GMT, (JAXAshby) wrote:


yeah, sure. rudder right, tranny forward, throttle forward and what happens
....???

Most times you go right. Sometimes you go left. If you've never gone
left when doing the above, you need some more experience.

sherr tells us the more experience he has the more he don't know which way his
boat is gonna go thusly:

Joxie, say it ain't so! With all your claimed sea experience you've
never had the boat turn in a different direction than where you had the
rudder pointed? Oh, that's right. You're just a hired hand with no
helm experience. If you had any time at the helm in poor conditions
you'd know just how foolish you're looking right about now.

Steve

push vs pull vis a vis rudders
 

schlackoff, when the wind and/or current was pushing me one way or the other I
knew it long before I put the boat in forward or reverse.

Maybe you didn't, but I did.

yeah, sure. rudder right, tranny forward, throttle forward and what
happens
....???

Most times you go right. Sometimes you go left. If you've never gone
left when doing the above, you need some more experience.

sherr tells us the more experience he has the more he don't know which way
his
boat is gonna go thusly:

Joxie, say it ain't so! With all your claimed sea experience you've
never had the boat turn in a different direction than where you had the
rudder pointed? Oh, that's right. You're just a hired hand with no
helm experience. If you had any time at the helm in poor conditions
you'd know just how foolish you're looking right about now.

Steve

push vs pull vis a vis rudders
 

schlackoff, when the wind and/or current was pushing me one way or the other I
knew it long before I put the boat in forward or reverse.

Maybe you didn't, but I did.

yeah, sure. rudder right, tranny forward, throttle forward and what
happens
....???

Most times you go right. Sometimes you go left. If you've never gone
left when doing the above, you need some more experience.

sherr tells us the more experience he has the more he don't know which way
his
boat is gonna go thusly:

Joxie, say it ain't so! With all your claimed sea experience you've
never had the boat turn in a different direction than where you had the
rudder pointed? Oh, that's right. You're just a hired hand with no
helm experience. If you had any time at the helm in poor conditions
you'd know just how foolish you're looking right about now.

Steve

push vs pull vis a vis rudders
 

JAXAshby wrote in message
...
Jim, I limited time for frauds. in this case rowell lied
straight out to us,
saying that professionally he was an expert in fluid flow.

Expert is a relative term. Compared to the majority of this news
group, he is a profesional expert in fluid flow. Different types
of fluid flow compared to those you were thinking of, maybe. I
speculate; hydraulics perhaps? A mere tool to him?

Yet, even his own
website drumming up business for his consulting services fails
to mention fluid
flow experience, let alone expertise.

He choice of words right from the get go indicated his
fraudulant
underpinnings.

Tut tut, Jax. Never use emotive adjectives if you're trying to
make a point among thoughtful people. As I said, it reduces your
credibility. Just let the facts speak for themselves.

JimB

push vs pull vis a vis rudders
 

JAXAshby wrote in message
...
Jim, I limited time for frauds. in this case rowell lied
straight out to us,
saying that professionally he was an expert in fluid flow.

Expert is a relative term. Compared to the majority of this news
group, he is a profesional expert in fluid flow. Different types
of fluid flow compared to those you were thinking of, maybe. I
speculate; hydraulics perhaps? A mere tool to him?

Yet, even his own
website drumming up business for his consulting services fails
to mention fluid
flow experience, let alone expertise.

He choice of words right from the get go indicated his
fraudulant
underpinnings.

Tut tut, Jax. Never use emotive adjectives if you're trying to
make a point among thoughtful people. As I said, it reduces your
credibility. Just let the facts speak for themselves.

JimB

push vs pull vis a vis rudders
 

Rodney Myrvaagnes wrote in message
...
On Wed, 31 Mar 2004 10:20:59 +0100, "JimB"
wrote:


[snip]
I'm trying to square Jax's flat 'nada' with rudder kick I've
observed, and an impression that the rudder direction affects
boat yaw when in reverse and not moving,
[snip]

I have observed the rudder kick in reverse, but only with the
boat in
motion. Does yours do this when tied to the dock?

It did in two previous vessels I've skippered, both of which had
big props a small distance from big rudders. Both also had
tillers, so force feedback was not hidden by gearing. It wasn't
big, but was apparent.

JimB