For years, on occasion, I've have been involved with teaching someone
boat handling, using single and/or twin screw inboards.
Naturally, (especially on twin screw+) the issue of rudder use arises (
from here we will consider this a twin screw+ discussion).
So that everyone knows, I am a STRONG proponent of rudder use, but I
understand many of the arguments against (G just don't agree with all
of them or feel the argument doesn't really address the issue).
In all of my discussions, I have had a problem with the term "steering",
as in "the boats moving too slow to steer with rudders", or "rudders are
not effective at these speeds".
At any rate, I knew I was never able to explain my point clearly and
concisely.
Recently, for some unknown reason, I remembered a TV show on jet
fighters which discussed (I believe) thrust vectoring, and it dawned on
me that this may be just the term to describe what I am trying to get
across to those I am teaching.
With this in mind, for those with twin screw boats, 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?

otn

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.

here you go, jeffies and wife. the underwater lawn sprinkler as shown by
Feynman (remember him?) on the first hit.

jeffies, people who claim to have a degree in physics should be able to
remember this stuff.

http://groups.google.com/groups?q=%2...an&hl=en&lr=&i
e=UTF-8&selm=4l58m4%24359%40newsbf02.news.aol.com&rnum =1

Thanks. Hands on IS the best teacher,G but we need to be able to
explain what just happened and why, when that poor newbie get's that
look of confused panic on his face, when what he just did, doesn't work.

otn

Jeff Morris wrote:
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.