"Shen44" wrote in message
...
One question otn asked, that you haven't answered ....when trying to walk, does
your bow go first , or your stern?


On this issue, I'm afraid, I have no recollection. I wish we had this discussion just a
few days ago, because I had several opportunities to experiment before I hauled. Of
course, my broken prop might have frustrated the experiments. We'll have to wait till
next year, or maybe I'll contact some sister ships.

Subject: Inherently beautiful.
From: "Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom
Date: 10/22/2003 18:12 Pacific Standard Time
Message-id:

"Shen44" wrote in message
...
One question otn asked, that you haven't answered ....when trying to walk,
does
your bow go first , or your stern?


On this issue, I'm afraid, I have no recollection. I wish we had this
discussion just a
few days ago, because I had several opportunities to experiment before I
hauled. Of
course, my broken prop might have frustrated the experiments. We'll have to
wait till
next year, or maybe I'll contact some sister ships.


LOL forgot you were seasonal..... try it next year.
If stern goes ahead of bow, solution easy and explains a good deal about your
props, if opposite, solution not so easy and may require a "wobble walk".

Shen

"Shen44" wrote in message
...
| Inherently beautiful.
| From: "Capt. Mooron"
|
|
| All very interesting ... I may not totally agree with your conclusions,
but
| there is some well thought out reasoning behind them.

Well Shen... elaborate.... where do you think my theory is wrong?

CM

"otnmbrd" wrote in message
nk.net...
| I can't agree here, although I've also heard this and there may be some
| validity to it. However, most ships I've been on, have very little angle
| on their shafts ..... they torque to port like an SOB, more so with
| engine speed than not.

Well I would expect that angle of the shaft affects direction of the prop
wash against the rudder... that would be plain common sense. I distinctltly
stated that I couldn't state one single overwhelming factor for propwash
from my experiences. I never claimed your theory to be false only that I
didn't completely agree with the premise.


| There are many reasons/factors which will affect "prop walk", and some
| boats will ignore it, if the wind/current is strong enough, but I'm also
| inclined to think "pitch" is the major factor, and Jeff's two bladed
| props may not have or need much for his application.

May I suggest reading for content rather than confrontation.... I wrote as
plain as day "I think the biggest villain is pitch and rudder placement as
well as flow and entry/exit of the prop wash."

| BTW Boobsprit, we will occasionally get into a ****ing match with Neal,
| since on rare instances he show's some trolling intelligence .... you
| are, on the other hand, a total waste of effort, not worth more than one
| or two responses on extremely rare occasions, purely to note your idiocy.

Now this petty, delusional, uncalled for, idiotic, uninspired statement just
blows your entire argument and casts doubt on the validity of your
intentions. If it's confrontation you want .... clarify that and I'll
accommodate you. It's not like you have the aptitude to contest me on either
a verbal or physical arena. You want to troll ... keep it on rec boats where
you have a chance of success. Around here you have little credibility and
absolutely no influence.

CM

Subject: Inherently beautiful.
From: "Capt. Mooron"
Date: 10/22/2003 18:32 Pacific Standard Time
Message-id:


"Shen44" wrote in message
...
| Inherently beautiful.
| From: "Capt. Mooron"
|
|
| All very interesting ... I may not totally agree with your conclusions,
but
| there is some well thought out reasoning behind them.

Well Shen... elaborate.... where do you think my theory is wrong?

CM


I, Like otn, do not agree with the angled shaft creating all that noticeable a
difference in "prop walk".
Although I may agree that a prop tunnel, may act similiar to a Kort nozzle, for
an open prop, I don't think the prop wash behind a wide keel, when going astern
will have a noticeable affect on prop walk.
However, if nothing else, I've learned that no matter how much some might try
to say that the handling of a particular boat with a particular set up, can be
described by science, this is just not so ....each boat must be figured out,
and this applies to boats of the same class.
One thing I would say is that I'm inclined to agree with the notion that a
folding prop may have less walk/bite, but I'm not sure that has everything to
do with the fact that it's folding or more to do with it's pitch .... I don't
have enough experience and knowledge of them to say.

Shen

Shen

"Shen44" wrote in message
| I, Like otn, do not agree with the angled shaft creating all that
noticeable a
| difference in "prop walk".

I wonder if "sucking" wash at an angle may reduce the effect of the rudder.
I don't believe the angle affects the walk by itself.... only influences the
wash over the rudder.

| Although I may agree that a prop tunnel, may act similiar to a Kort
nozzle, for
| an open prop, I don't think the prop wash behind a wide keel, when going
astern
| will have a noticeable affect on prop walk.

Don't the newer cruise ships now use pod screws for better control and
performance? That would be like a prop in reverse ... sort of.

| However, if nothing else, I've learned that no matter how much some might
try
| to say that the handling of a particular boat with a particular set up,
can be
| described by science, this is just not so ....each boat must be figured
out,
| and this applies to boats of the same class.

I concur.

| One thing I would say is that I'm inclined to agree with the notion that a
| folding prop may have less walk/bite, but I'm not sure that has everything
to
| do with the fact that it's folding or more to do with it's pitch .... I
don't
| have enough experience and knowledge of them to say.

Well since none of us are experts in the field it only makes for a venue to
compare alternate viewpoints. It's of interest only to those of us who
consider the problem and wish to explore the situation.

CM

ROFL, Cool your jets, Mooron ... I'm not confronting you, I'm talking to
you .....comments interspersed:

Capt. Mooron wrote:
"otnmbrd" wrote in message
nk.net...
| I can't agree here, although I've also heard this and there may be some
| validity to it. However, most ships I've been on, have very little angle
| on their shafts ..... they torque to port like an SOB, more so with
| engine speed than not.

Well I would expect that angle of the shaft affects direction of the prop
wash against the rudder... that would be plain common sense. I distinctltly
stated that I couldn't state one single overwhelming factor for propwash
from my experiences. I never claimed your theory to be false only that I
didn't completely agree with the premise.

Quite possibly correct, but when going astern, there would be no prop
wash past the rudder and I would say most would see the affects of
propwalk to a greater degree when backing. G You don't have to
completely agree with me any more than I do with you. We're talking the
possibilities, here.


| There are many reasons/factors which will affect "prop walk", and some
| boats will ignore it, if the wind/current is strong enough, but I'm also
| inclined to think "pitch" is the major factor, and Jeff's two bladed
| props may not have or need much for his application.

May I suggest reading for content rather than confrontation.... I wrote as
plain as day "I think the biggest villain is pitch and rudder placement as
well as flow and entry/exit of the prop wash."

G The only confrontation, was in your own reading of the content. My
statement was that I felt it was mainly pitch (shoulda, coulda said
also). I don't think it has as much to do with rudder placement although
flow and entry/exit of the wash from the prop probably does count.

| BTW Boobsprit, we will occasionally get into a ****ing match with Neal,
| since on rare instances he show's some trolling intelligence .... you
| are, on the other hand, a total waste of effort, not worth more than one
| or two responses on extremely rare occasions, purely to note your idiocy.

Now this petty, delusional, uncalled for, idiotic, uninspired statement just
blows your entire argument and casts doubt on the validity of your
intentions. If it's confrontation you want .... clarify that and I'll
accommodate you. It's not like you have the aptitude to contest me on either
a verbal or physical arena. You want to troll ... keep it on rec boats where
you have a chance of success. Around here you have little credibility and
absolutely no influence.

CM

ROFL the last paragraph was dedicated to Boobsprit, as an afterthought
(figure he reads them all) and had nothing to do with you (read for
content). Seems to me, the only one here looking for confrontation, is
you, I was having a discussion .....

otn

Subject: Inherently beautiful.
From: "Capt. Mooron"


"Shen44" wrote in message
| I, Like otn, do not agree with the angled shaft creating all that
noticeable a
| difference in "prop walk".

I wonder if "sucking" wash at an angle may reduce the effect of the rudder.
I don't believe the angle affects the walk by itself.... only influences the
wash over the rudder.

BG This may be part of the problem you are having with otn's comments.
Generally, when we discuss prop walk, we relate it to backing, not ahead
motions of the prop. Prop walk, when going ahead, is there and useful or
harmful, depending, but not as noticeable or well used as when going
astern.(which also means we may be trying to make totally different points)
I'm not sure what you mean by "sucking wash" regarding the effects of and on
the rudder?
The angle of the shaft, may well affect the wash across the rudder and how it
responds, but I would assume (right or wrong) that that may be accounted for by
some of the "tear drop" shapes you see in some rudders....only a guess.

| Although I may agree that a prop tunnel, may act similiar to a Kort
nozzle, for
| an open prop, I don't think the prop wash behind a wide keel, when going
astern
| will have a noticeable affect on prop walk.

Don't the newer cruise ships now use pod screws for better control and
performance? That would be like a prop in reverse ... sort of.

Azipods (was on one last weekend) They are more like a outboard drive that can
turn 360 deg (electric motor in the pod) independantly of each other .... kind
of like Z-drives on a tug. Yes, make for a highly maneuverable ship.


Shen

After starting this little brouhaha I think I might have to modify my claim that my cat
has no prop walk.

Since the props are widely spaced (15 feet with an 18 foot beam) if I ever tried to back
on one engine the boat would "spin out" immediately. Although the boat is functional with
one engine in forward, it is rather crippled for maneuvers in reverse.

Therefore, anytime I would be running one engine in close quarters, I would be also be
running the other, and likely balancing so that it would back true, or adjusting to turn
as desired. The only way I could tell that I had no prop walk would be to carefully
measure the RPMs, and this is beyond my instrumentation.

Thus, the net affect is zero propwalk, but I have no way to determine whether the
individual engines are generating propwalk.

BTW, the builder claimed this was a non-issue, but when they started building larger
sailing cats, and the powercat, they used counter-rotating props, because it was an option
with the larger transmissions.


"Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom wrote in message
...
My props are Left-Hand, two blade folding. There is virtually no propwalk. I'm quite
familiar with the phenomenon because my old Nonsuch would walk hard to port, as would
all
the single screw boats I've driven.

I was under the impression that a major contributor to prop walk was the angle of the
shaft; thus, if its horizontal, the affect is greatly reduced. If this isn't the case,
what does cause it?

-jeff



"Shen44" wrote in message
...
Subject: Inherently beautiful.
From: "Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom
Date: 10/22/2003 13:00 Pacific Standard Time
Message-id:

Neal really doesn't understand, even though I explained it fully. He'll
figure it out and
come up with a creative way to cover his ignorance!

BTW, I get virtually no prop walk - is that because the shaft is horizontal,
the blades
are flat, the keel is long, or a combination of all three?


None of the three SHOULD eliminate "prop walk", singly or in combination ....
G you don't have Kort nozzles, do you?
To be sure I'm thinking correctly, both your props are right hand, folding? (I
have no experience with folding, so I don't know if this may be a factor).

When backing, your boat, should want to back to port, as Neal said, once you
lose steerageway .... does it? (assuming two right hand props ... I can't
remember if you said right or left).

Shen

Jeff Morris wrote:
After starting this little brouhaha I think I might have to modify my claim that my cat
has no prop walk.

Since the props are widely spaced (15 feet with an 18 foot beam) if I ever tried to back
on one engine the boat would "spin out" immediately. Although the boat is functional with
one engine in forward, it is rather crippled for maneuvers in reverse.

Understandable. With that spacing, you'd HAVE to expect "donuts", on one
engine astern, prop walk, or no prop walk.

Therefore, anytime I would be running one engine in close quarters, I would be also be
running the other, and likely balancing so that it would back true, or adjusting to turn
as desired. The only way I could tell that I had no prop walk would be to carefully
measure the RPMs, and this is beyond my instrumentation.

A simple test, would be both engines astern, equally. Since they are
both "left hand", your boat should immediately start backing to stbd.
How quickly and at what "turn rate", would indicate the degree of prop walk.
I'm guessing here, but I'm betting you can steer your boat astern by
just increasing/decreasing throttle on one or the other of the engines?


Thus, the net affect is zero propwalk, but I have no way to determine whether the
individual engines are generating propwalk.

Another way would be back on port engine and get a sense of "turn rate",
then back on stbd and compare (backing on stbd, could/should produce a
slower turn rate)

BTW, the builder claimed this was a non-issue, but when they started building larger
sailing cats, and the powercat, they used counter-rotating props, because it was an option
with the larger transmissions.

Your transmission/reverse gear is only built to turn in one direction?
Can't be built to turn opposite?

Overall, I'm guessing that the spacing of your props, andG as mooron
says, the fact you have folding props of relatively little "bollard
pull" means that for most maneuvers you do, prop walk will be there, but
not of enough significance, when compared to the reaction of your boat
to the spacing and thrust of your props, so, as the builders claim, it
will generally be a non issue.

otn