if I told you that
rudders were important tools of boat handling, but not to be considered
for steering, rather for "thrust vectoring", when maneuvering around a
dock, etc., when kicking an engine ahead, both positive and negative
...... would you understand what I was saying?

I would know you are bull****ting, for pulling water over a rudder with a prop
does not -- and can not under the laws of physics -- affect the direction a
boat is moving.

otn

Subject: Thrust vectoring
From: (JAXAshby)
Date: 03/24/2004 19:39 Pacific Standard Time
Message-id:

if I told you that
rudders were important tools of boat handling, but not to be considered
for steering, rather for "thrust vectoring", when maneuvering around a
dock, etc., when kicking an engine ahead, both positive and negative
...... would you understand what I was saying?

I would know you are bull****ting, for pulling water over a rudder with a
prop
does not -- and can not under the laws of physics -- affect the direction a
boat is moving.

otn

Since I know Otn has jaxass killfiled, I'll quote this nonsense so otn can read
it.

Shen

Otn has jaxass killfiled,

is over the nee a blockhead?

Interesting. I can't think of too many boats that "pull" water over a
rudder for steering, except in reverse, and this is well known to be,
generally, of little effect.
Of course, considering the source of that statement, we realize it has
no value, other than to say he didn't understand what I was saying, nor
does he have any knowledge of the subject.
G I'll call that a "negative", with reservations.....
Come-on group, I'm looking for some pos/neg responses from people with
some knowledge and experience, not jaxasses .....

otn

Shen44 wrote:
Subject: Thrust vectoring
From: (JAXAshby)
Date: 03/24/2004 19:39 Pacific Standard Time
Message-id:

if I told you that
rudders were important tools of boat handling, but not to be considered
for steering, rather for "thrust vectoring", when maneuvering around a
dock, etc., when kicking an engine ahead, both positive and negative
...... would you understand what I was saying?

I would know you are bull****ting, for pulling water over a rudder with a
prop
does not -- and can not under the laws of physics -- affect the direction a
boat is moving.

otn


Since I know Otn has jaxass killfiled, I'll quote this nonsense so otn can read
it.

Shen

Interesting. I can't think of too many boats that "pull" water over a
rudder for steering, except in reverse, and this is well known to be,
generally, of little effect.

zero effect. none.

My first few lessons in small powerboat handling as a young lad included "thrust
vectoring" examples, although those terms were never used. I remember vividly
bringing the launch (about 18 feet with an Atomic 4 and a "stick" tiller) bow to
the dock and wagging the butt back and forth with the tiller. The exercise was
repeated in reverse hanging off a bow line, proving (contrary to jaxie's claim)
the affect works in reverse, although with greatly diminished results. These
exercises were an eye-opener for me, since as a sailor, I had never thought in
terms of water flow created by a prop.

A few years later I had another lesson (I should have known better by then) when
I tried to power off of a dock at Castine, ME with a very strong current
flowing. An old hand showed me the "power against a spring line" trick. I was
amazed that so much power could be brought to bear.

These techniques are best taught "hands on," in a small boat, if possible, so
that one can feel the power the prop can generate. Whether the words "thrust
vectoring" are used depends on the audience.





"otnmbrd" wrote in message
hlink.net...
Interesting. I can't think of too many boats that "pull" water over a
rudder for steering, except in reverse, and this is well known to be,
generally, of little effect.
Of course, considering the source of that statement, we realize it has
no value, other than to say he didn't understand what I was saying, nor
does he have any knowledge of the subject.
G I'll call that a "negative", with reservations.....
Come-on group, I'm looking for some pos/neg responses from people with
some knowledge and experience, not jaxasses .....

The exercise was
repeated in reverse hanging off a bow line, proving (contrary to jaxie's
claim)
the affect works in reverse,

geezus kriste, jeffies, you claim to have a degree in physics and have NEVER --
to this moment -- heard of classic "under water lawn sprinkler" paradox that
ALL physics students learn.

Get your wife to explain it to you. It is impossible to steer by *pulling*
water over a rudder with a prop. Can't be done, except when under the
influence of hard drugs.

OK, jaxie, please explain Feynman's Sprinkler Paradox and give us your answer.
And why do you think this is relevant?

Are you claiming that an object placed on the "suction side" of a propeller will
not feel an affect, that is it cannot be deflected to one side if it
asymmetrical?


"JAXAshby" wrote in message
...
The exercise was
repeated in reverse hanging off a bow line, proving (contrary to jaxie's
claim)
the affect works in reverse,

geezus kriste, jeffies, you claim to have a degree in physics and have
NEVER --
to this moment -- heard of classic "under water lawn sprinkler" paradox that
ALL physics students learn.

Get your wife to explain it to you. It is impossible to steer by *pulling*
water over a rudder with a prop. Can't be done, except when under the
influence of hard drugs.

Are you claiming that an object placed on the "suction side" of a propeller
will
not feel an affect, that is it cannot be deflected to one side if it
asymmetrical?

yes, of course I am saying that. you would too if you had the degree in
physics you claim you have.

Sorry Jax, sometimes you get it right, but this time your habit of
stating absolutes where not appropriate is showing again. The
underwater lawn sprinkler is an imperfect model for the mechanics of a
boat's prop and rudder. Now, a prop in reverse creates very little
water movement past the rudder compared to one in forward, but very
little is not the same as none. As long as there is water being moving
past and deflected by the rudder there will be some lateral force
generated. Not much in this case, but some. This can be readily
demonstrated as another poster pointed out.

JAXAshby wrote:
The exercise was
repeated in reverse hanging off a bow line, proving (contrary to jaxie's
claim)
the affect works in reverse,


geezus kriste, jeffies, you claim to have a degree in physics and have NEVER --
to this moment -- heard of classic "under water lawn sprinkler" paradox that
ALL physics students learn.

Get your wife to explain it to you. It is impossible to steer by *pulling*
water over a rudder with a prop. Can't be done, except when under the
influence of hard drugs.



--
Dan Best - (707) 431-1662, Healdsburg, CA 95448
B-2/75 1977-1979
Tayana 37 #192, "Tricia Jean"
http://rangerbest.home.comcast.net/TriciaJean.JPG