Inherently beautiful.
 

Depends on whether it it a right or left hand screw of course.

Cheers MC

Simple Simon wrote:

Walking and rudder power are intmately related.

Walking is more a natural function of how a propeller works
that has to be counteracted by a rudder to keep it from
having its way.

For example, you are aboard a right-handed single screw
vessel with headway on. The engine is put full astern and
the rudder hard left. The bow will first swing to the left and
the swing to the right as the vessel loses way.

The swing of the bow to the left is a function of rudder control
while the swing to the right as the vessel loses way is caused
by the prop walk overcoming the effects of the rudder because
of the decreased speed and decreased rudder control.

I hope this helps.

S.Simon.

"otnmbrd" wrote in message k.net...


DSK wrote:


In harbors the world over. I mean everywhere, We all know where they put
Multi-Hulls. on the very end slips of finger piers or bouyed mooring.

The Captains Nemesis wrote:
Interesting.
Here the cats tend to be deep into the marinas (other than casuals)
because they have the ability to turn in there own length under power


No doubt that cats under power with wide spaced twin engines are very
maneuverable under power.



Let's face facts; a Multi trying to manouver ( Over even making a simple
turn in tight quarters) is not a pretty thing. Even under power.

Skilled hands make light work under power. Juggling thrust can walk a
cat sideways and maneuver in ways that monos can only dream.


I'd like to see that. Theory suggests that with small props & rudders, prop
walk and kick aren't going to move it sideways much. In practice??

Interesting .... I'd have thought the opposite.
Since "walking" is highly dependent on rudder power and most sailboats
tend to have better than average power in this area and a "cat" doesn't
tend to have a great deal of wetted area and or windage (exceptions
noted), I'd have guess them to be good candidates for "walking".

otn

Inherently beautiful.
 

Pages written by lubbers! Fancy not saying what hand the screws are!

Cheers MC

Jeff Morris wrote:

2GM20FC with SD20 Saildrive, bottom of page:
http://www.yanmar.com.au/marine/Sail...sailseries.htm

Also, the props are shown on this page - search for 872880
http://www.penta.volvo.se/files/kapitel45-gb.pdf

"Simple Simon" wrote in message
...

Hey silly, Yanmars turn clockwise looking at them from the stern.

Unless you have a weird, v-drive tranny or something your props
turn clockwise.

S.Simon

"Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom wrote in message

...

Both turn the same way, Counterclockwise, when viewed from the stern. I think. I
actually had a prop in my hand this afternoon to bring home, and decided that was

silly!

But I do know for sure they both go the same way!

"otnmbrd" wrote in message
thlink.net...

G May be wrong answer .... when looking from astern, both props turn
clockwise, when engines ahead? or does stbd turn one way and port, the
other? (may be part of the reason for no walk).

otn

Jeff Morris wrote:

Yes.

There're not counter-rotating.

As to what happens when I try to "walk" - I can't quite remember exactly - she

just

jiggles forward or back but never really gets and loser to the dock! Of course, I

wish we

had this discussion yesterday, I could have tried it out this morning! But as

they

say

here in Boston, "Wait till next season!"

"otnmbrd" wrote in message
rthlink.net...


Dang it! That's twice I forgot to ask .....inboard or outboard turning
props?

otnmbrd wrote:


Walk set-up is correct (props control bow, rudders control stern). Don't
think your keel (from what I saw in the picture) is the problem.
Seemingly (but not) unimportant question .... which end lags behind ....
bow or stern? (in your example, hard right rudder, engines clutched,
only,[no throttle] for left twist) BTW, I'm hoping you say bow, lags
behind G.

otn

Jeff Morris wrote:



Oy! You had to ask! It isn't easy to remember with the controls in
front of me, but I
guess:

To walk to Port, Rudders to Starboard, Port Engine in Reverse,
Starboard Engine Forward.

The works with many twin screw boats, but I think mine has a keel that
too long - I wonder
if its too efficient at low speed? Also, although the rudders are
large, they are hung on
skegs and set back a bit from the screws, which are folding. I think
all these things add
up to minimal "walking."

-jeff



"otnmbrd" wrote in message
.earthlink.net...



G It varies a lot with all multi screw (except tractor tugs). From the
look at the picture, I would think she'd "walk" fairly well ( I'm
talking about sideways motion, not prop walk).
Just out of curiosity, when you set up to "walk" to stbd, how do you set
your engines and rudders? .... and which part has the problem keeping
up, bow or stern?

otn

Jeff Morris wrote:



And the answer is:

It varies a lot with the cat. Some have long keels, others have
daggerboards. Some


have



steerable drives, some have a single outboard, some have a widely
spaced diesels.


Some



have little windage, others a lot.

My boat has long keels, low windage on the bow (more aft), and
widely space diesels.


She



can pivot in place very nicely but has little prop walk. People
have told me they


could



make it go sideways, but when I've challenged them to try, they've
always failed. I


often



have to dock on a face, which is actually often tough - I usually
rely on getting


close



enough to snag a cleat, then springing in the rest of the way. If I
have a few hands
around to help I can usually get the boat anywhere I want. The
hands don't have to do
much of anything, but I find it difficult to singlehand because the
visibility around


the



edges is limited.

This morning I had a special challenge - I had to back into a
TravelLift the is about


6



inches wider than my beam. The wind started light, but picked up
to about 15 knots


cross



as I was coming in. The real problem was that one prop had trouble
staying open in
foreword - I had to do most of the work with just one engine. This
made it difficult


to



stay lined up. I felt that I totally turkeyed it, but I was
complimented by the Lift-
Meister and dockhand, and no damage was done. I found that the
gearing that forces to


two



blades to open together had totally sheared off.

Here's a pic taken slightly later:
http://www.sv-loki.com/Img_1616a.jpg

Inherently beautiful.
 

Depends on whether it it a right or left hand screw of cours

Neal rarely gets either.

RB

Inherently beautiful.
 

I'm just the opposite - I can't bear the thought of
having it done without being there.

I feel the same way but I cringe through the whole process....ever seen =
one dropped? It ain't pretty....
--=20
katysails
s/v Chanteuse
Kirie Elite 32
http://katysails.tripod.com

"Women and cats will do as they please, and men and dogs should relax
and get used to the idea." - Robert A. Heinlein

Inherently beautiful.
 

Subject: Inherently beautiful.
From: =?ISO-8859-1?Q?The=5Fnavigator=A9?=
Date: 10/21/2003 13:07 Pacific Standard Time
Message-id:

Depends on whether it it a right or left hand screw of course.

Cheers MC

Simple Simon wrote:

Walking and rudder power are intmately related.


The discussion in question, was way over Neal's head and/or experience.

Shen

Inherently beautiful.
 

Why do you say that? Why did you decline to respond
to my post about the affects of rudder vs. prop walk
in the situation I described? Was it because you failed
to understand what was said?

S.Simon


"Shen44" wrote in message ...

The discussion in question, was way over Neal's head and/or experience.

Shen

Inherently beautiful.
 

Subject: Inherently beautiful.
From: "Simple Simon"
Date: 10/22/2003 05:36 Pacific Standard Time
Message-id:

Why do you say that? Why did you decline to respond
to my post about the affects of rudder vs. prop walk
in the situation I described? Was it because you failed
to understand what was said?

S.Simon


This post, and the one, from you, which brought about my response, highlights
the reason for my response.
They were not talking about single screw "prop walk". They were talking about
making, or the possibilities of making, a twin screw boat "walk" sideways.
Your post was a dissertation on a basic "motorboat" maneuver, with a fixed
pitch, right hand propellor. (possible exceptions noted)
The fact you weren't aware of this and made your post, showed that the topic
was "over your head and/or beyond your experience".

Shen

Inherently beautiful.
 

Duh! Two fixed props spinning in the same direction
as on Jeff's catamaran will act the same was as one
fixed prop on a monohull.

You sure you're a licensed captain. You just aren't
too bright.

S.Simon


"Shen44" wrote in message ...
Subject: Inherently beautiful.
From: "Simple Simon"
Date: 10/22/2003 05:36 Pacific Standard Time
Message-id:

Why do you say that? Why did you decline to respond
to my post about the affects of rudder vs. prop walk
in the situation I described? Was it because you failed
to understand what was said?

S.Simon


This post, and the one, from you, which brought about my response, highlights
the reason for my response.
They were not talking about single screw "prop walk". They were talking about
making, or the possibilities of making, a twin screw boat "walk" sideways.
Your post was a dissertation on a basic "motorboat" maneuver, with a fixed
pitch, right hand propellor. (possible exceptions noted)
The fact you weren't aware of this and made your post, showed that the topic
was "over your head and/or beyond your experience".

Shen

Inherently beautiful.
 

Subject: Inherently beautiful.
From: "Simple Simon"
Date: 10/22/2003 10:07 Pacific Standard Time
Message-id:

Duh! Two fixed props spinning in the same direction
as on Jeff's catamaran will act the same was as one
fixed prop on a monohull.

You sure you're a licensed captain. You just aren't
too bright.

S.Simon


ROFLMAO DUH!!! You STILL don't understand what was being discussed ..... as
stated twice before WAY over your head and experience!!


Shen

Inherently beautiful.
 

From: (Shen44)
Date: 10/22/2003 10:39 Pacific Standard Time
Message-id:

Subject: Inherently beautiful.
From: "Simple Simon"
Date: 10/22/2003 10:07 Pacific Standard Time
Message-id:

Duh! Two fixed props spinning in the same direction
as on Jeff's catamaran will act the same was as one
fixed prop on a monohull.

You sure you're a licensed captain. You just aren't
too bright.

S.Simon


ROFLMAO DUH!!! You STILL don't understand what was being discussed ..... as
stated twice before WAY over your head and experience!!


Shen


Snif? Snif? Smell the beginnings of an electrical overload, as Neal frantically
searches the web, looking for information on twin screw "walking"

Shen

Inherently beautiful.
 

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?


"Shen44" wrote in message
...
From: (Shen44)
Date: 10/22/2003 10:39 Pacific Standard Time
Message-id:

Subject: Inherently beautiful.
From: "Simple Simon"
Date: 10/22/2003 10:07 Pacific Standard Time
Message-id:

Duh! Two fixed props spinning in the same direction
as on Jeff's catamaran will act the same was as one
fixed prop on a monohull.

You sure you're a licensed captain. You just aren't
too bright.

S.Simon


ROFLMAO DUH!!! You STILL don't understand what was being discussed ..... as
stated twice before WAY over your head and experience!!


Shen


Snif? Snif? Smell the beginnings of an electrical overload, as Neal frantically
searches the web, looking for information on twin screw "walking"

Shen

Inherently beautiful.
 

Hey, I'm a sailor. I don't muck around with big,
ugly motorboats if I can help it.

And, yes, I've operated a twin-screw cat bigger
than yours. Have you ever heard of a Corithian?

S.Simon


The Captains Nemesis wrote in message ...
On Wed, 22 Oct 2003 13:07:50 -0400, "Simple Simon"
wrote:

Duh! Two fixed props spinning in the same direction
as on Jeff's catamaran will act the same was as one
fixed prop on a monohull.

You sure you're a licensed captain. You just aren't
too bright.

S.Simon

So you STILL don't understand!

Ever been onboard a twin screwed vessel at any time it was docking?


Oz1...of the 3 twins.
Who spends an hour tuning before every race not just when new sails go on
I welcome you to crackerbox palace,We've been expecting you.

Inherently beautiful.
 

Have you ever heard of a Corithian?

Yes...rich and soft, found in my dad's old Oldsmobile!

RB

Inherently beautiful.
 

ject: Inherently beautiful.
From: "Simple Simon"
Date: 10/22/2003 14:29 Pacific Standard Time
Message-id:

Hey, I'm a sailor. I don't muck around with big,
ugly motorboats if I can help it.


Which is just one of the reasons the discussion was over your head.

Shen

Inherently beautiful.
 

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

Inherently beautiful.
 

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

Inherently beautiful.
 

I believe Shen is wrong here Jeff and you are right. The angle of the shaft
would definitely affect propwalk. It's not the only factor but it will
contribute. I think the biggest villain is pitch and rudder placement as
well as flow and entry/exit of the prop wash.

I think there is less propwalk on folding/ feathering props. I carry a
13"x19# LH 3 bladed prop with a stern hung tiller that is the size of a
small barn door. The prop well unfortunately is small and my upper clearance
is only 4". The keel is 5" thick at the shaft and this affects the flow to
the prop and correspondingly to the rudder in reverse.

Wouldn't it be wise in a twin screw configuration to have counter-rotating
props? This would eliminate propwalk altogether. I was coxswain on a Aux CCG
with a pair of matched outboards and counter-rotating props.... I could
station keep that bugger in the worst conditions with no problems.

CM


"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
|
|

Inherently beautiful.
 

Subject: Inherently beautiful.
From: "Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom
Date: 10/22/2003 16:33 Pacific Standard Time
Message-id:

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


OK, sorry, I thought you said right hand .... your boat should back to stbd
..... does it?
Possibly, your lack of prop walk may have more to do with the two blade
configuration than the direction .... I have always considered two bade props,
"speed props" which have little "bollard pull" on their own, thus, little
"walk" characteristics.
I have heard a number of people say that horizontal shafts tend to have less
prop walk... there may well be some scientific reasoning and proof to this, but
I've seen a number of outboards with a major walk to port (right hand).
To me, the major reason for prop walk, is the pitch of the propellor (more
pitch, more walk) as I feel it's this pitch angle, pulling against the water,
sideways, at whatever angle, which is creating the walk. (G Mooron doesn't
agree .... no problem, he might be correct, technically and in many cases
realistically, but my experience says otherwise).
One question otn asked, that you haven't answered ....when trying to walk, does
your bow go first , or your stern?

I'm inclined to think, your two bladed prop configuration, more than anything,
is the reason, but without actually feeling and handling your boat, it's hard
to tell.

Shen

Inherently beautiful.
 

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.

Shen

I believe Shen is wrong here Jeff and you are right. The angle of the shaft
would definitely affect propwalk. It's not the only factor but it will
contribute. I think the biggest villain is pitch and rudder placement as
well as flow and entry/exit of the prop wash.

I think there is less propwalk on folding/ feathering props. I carry a
13"x19# LH 3 bladed prop with a stern hung tiller that is the size of a
small barn door. The prop well unfortunately is small and my upper clearance
is only 4". The keel is 5" thick at the shaft and this affects the flow to
the prop and correspondingly to the rudder in reverse.

Wouldn't it be wise in a twin screw configuration to have counter-rotating
props? This would eliminate propwalk altogether. I was coxswain on a Aux CCG
with a pair of matched outboards and counter-rotating props.... I could
station keep that bugger in the worst conditions with no problems.

CM

Inherently beautiful.
 

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.
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.

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.

otn

Capt. Mooron wrote:
I believe Shen is wrong here Jeff and you are right. The angle of the shaft
would definitely affect propwalk. It's not the only factor but it will
contribute. I think the biggest villain is pitch and rudder placement as
well as flow and entry/exit of the prop wash.

I think there is less propwalk on folding/ feathering props. I carry a
13"x19# LH 3 bladed prop with a stern hung tiller that is the size of a
small barn door. The prop well unfortunately is small and my upper clearance
is only 4". The keel is 5" thick at the shaft and this affects the flow to
the prop and correspondingly to the rudder in reverse.

Wouldn't it be wise in a twin screw configuration to have counter-rotating
props? This would eliminate propwalk altogether. I was coxswain on a Aux CCG
with a pair of matched outboards and counter-rotating props.... I could
station keep that bugger in the worst conditions with no problems.

CM


"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
|
|

Inherently beautiful.
 

"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.

Inherently beautiful.
 

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

Inherently beautiful.
 

"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

Inherently beautiful.
 

"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

Inherently beautiful.
 

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

Inherently beautiful.
 

"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

Inherently beautiful.
 

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

Inherently beautiful.
 

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

Inherently beautiful.
 

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

Inherently beautiful.
 

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

Inherently beautiful.
 

interspersed ...

"otnmbrd" wrote in message
ink.net...

....


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?


I don't recall the boat ever doing anything other then going straight back as it first
started up.

Yes, I back down a long narrow fairway with throttle alone, rudders centered.




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)

Yes, I should try that, if only to get an answer to this question.




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?

No, obviously there is a reverse, but many transmissions favor one direction amd the
other is only for intermittant use. There are differences in the gearing and the
lubrication. Other transmissions can be set up either way. I don't know what the issue
is with the small Volvo and Yanmar saildrives but the only props they (Volvo) make for
them are LH - I take that as a sign.

There is an often talked about case of a trawler that was setup counter rotating by
running one tranny in reverse. It took them a while to figure out why that transmission
always cooked in a few hundred hours.




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.


maybe so, maybe so.

otn

Inherently beautiful.
 

I had a situation with a Seawind 1000 that in some ways contradicts
the statement of being crippled in reverse with only one engine.

I was in a rather narrow channel and was waiting to dock. The
best was to do it in this situation was to back to the dock square
on the stern of the boat, step off and tie off the starboard side, then
use the port engine forward to bring the boat around for a side tie
on the starboard side (wind, current, tight quarters were the issues
involved).

During the wait for the other, larger mono to get the f*ck out of
the way, the starboard engine died and wouldn't restart (can't recall
what the problem was right now). I still managed to do the same
maneuver but it took longer and I had to jockey back and forth
a couple of times. Perhaps it's just a matter of taking it easy with
not too much engine.

Of course, forward has never been a problem on several large
cats. In Belize, the port engine was sounding funny one day
when we were in "get there" mode. I just turned it off and raised it
while we kept going.

Jonathan

"Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom wrote in message
...
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

Inherently beautiful.
 

G Also interspersed

Jeff Morris wrote:

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?



I don't recall the boat ever doing anything other then going straight back as it first
started up.

Interesting, G another test for next year?

Yes, I back down a long narrow fairway with throttle alone, rudders centered.

Sounds like a twin screw with outboard turning props, although we know
this isn't the case.
Think we're learning some things about "cats" here ... have a feeling
it's mainly due to spacing/hull length.




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)


Yes, I should try that, if only to get an answer to this question.




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?


No, obviously there is a reverse, but many transmissions favor one direction amd the
other is only for intermittant use. There are differences in the gearing and the
lubrication. Other transmissions can be set up either way. I don't know what the issue
is with the small Volvo and Yanmar saildrives but the only props they (Volvo) make for
them are LH - I take that as a sign.

I say transmission/reverse gear, purely to note different terms for the
same thing.
It's interesting to note they only make the "gear" for left hand
.....wonder why....

There is an often talked about case of a trawler that was setup counter rotating by
running one tranny in reverse. It took them a while to figure out why that transmission
always cooked in a few hundred hours.

Have run across this situation in the past. It's not normally a quick
presto - chango. Sometimes engines were and possibly still are, built to
run opposite, and I remember one Boston ferry, was built with engines
gears set up for inboard turning props ( shocked the hell out of the
operator, first time he maneuvered it, since it didn't react at all like
what he was used to or expecting). It was, I believe, done
inadvertently, and they ended up switching gears and props to outboard
turning.

otn




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.



maybe so, maybe so.


otn

Inherently beautiful.
 

Yes there's always a way to get things done. I usually want to dock by pushing against a
spring, but the person on the dock inevitably runs the line forward instead of aft, so I
have to pull on it. I've given up planning too much, because the plans always seem to get
foiled at the last second. Fortunately, with the twins there are a lot of options.

I remember once talking to folks in a Manta 42 - they had just got a tow in from an
anchorage about 10 miles up the ICW. They had lost a prop and were afraid to bring the
boat in with one engine. I was surprised, but I understand - especially if they had
"unlimited" tow insurance.


"Jonathan Ganz" wrote in message
...
I had a situation with a Seawind 1000 that in some ways contradicts
the statement of being crippled in reverse with only one engine.

I was in a rather narrow channel and was waiting to dock. The
best was to do it in this situation was to back to the dock square
on the stern of the boat, step off and tie off the starboard side, then
use the port engine forward to bring the boat around for a side tie
on the starboard side (wind, current, tight quarters were the issues
involved).

During the wait for the other, larger mono to get the f*ck out of
the way, the starboard engine died and wouldn't restart (can't recall
what the problem was right now). I still managed to do the same
maneuver but it took longer and I had to jockey back and forth
a couple of times. Perhaps it's just a matter of taking it easy with
not too much engine.

Of course, forward has never been a problem on several large
cats. In Belize, the port engine was sounding funny one day
when we were in "get there" mode. I just turned it off and raised it
while we kept going.

Jonathan

"Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom wrote in message
...
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

Inherently beautiful.
 

The biggest factor is the interaction of the prop with the hull.

Cheers MC

Jeff Morris wrote:

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

Inherently beautiful.
 

No, Bob, its not your fathers Oldsmobile, Ricardo Montleban (sp),
Chrysler, " fine, corinthian leathooooooor. Remember ?

On 22 Oct 2003 21:50:48 GMT, (Bobsprit) wrote:

Have you ever heard of a Corithian?

Yes...rich and soft, found in my dad's old Oldsmobile!

RB

Inherently beautiful.
 

Shen,

You're way off about two bladed and folding. I have a single prop mono
hull and I use both a fixed Martec and at times a Martec Folding, Both
13x13. They both walk. The Folding much worst than the fixed, due the
the need of higher RPM's initially to open the blades

Jeff I don't have the answer of why you don't walk but I would suspect
it has to do with the Saildrives. Walking occurs on bare props. The
Saildrives have cavition plate and shaped housing forward and shedges
below which control the water flow to aid forward and stern direction

You, my friend, are BLESSED with a vessel that goes forward and back in
a straight line. Give thanks!!

"I'LL DRINK TO THAT!"

Ole Thom

Inherently beautiful.
 

CM,

You must be over doing it on the "Overproof!" Jeff has "Zero" prop
walking.
Why in the world does he need a counter rotating engine?

OT

Inherently beautiful.
 

"otnmbrd" wrote in message
nk.net...
| ROFL, Cool your jets, Mooron ... I'm not confronting you, I'm talking to
| you .....comments interspersed:

Warp engines offline, standing down, docking thrusters activated. :-)

Amazing what a "we" before the will can cause when it's not picked up in the
initial read through!
I'd kick myself but I'm having too much fun laughing at my own expense!


| 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.

Gothcha... I'm just not correctly differentiating between flow and wash on
the prop in my original reply. My prop actually becomes narrower further
down. The prop is angled so that the flow would be strongest at the point
where it begins to narrow the most. I believe that's the reason I have such
a bitch of a time with propwalk to starboard in reverse.

CM

Inherently beautiful.
 

No, Bob, its not your fathers Oldsmobile, Ricardo Montleban (sp),
Chrysler, " fine, corinthian leathooooooor. Remember ?

I do indeed. Sad to see him in a wheelchair these days. His knee problems
plagued him all his life, even when he was a champion swimmer.
Khan!!!!!

RB