and the thing has a fairly
significant reduction in drag, over a fixed prop yes?

no. but keep telling yourself that, jimmy. it will help justify spending
$2,200, plus installation, to gain 1/10th knot under perfect conditions.

I do find JAXAshby's posts amusing however. although I suppose it's rude
to toy with the retarded kid.

I am sorry, jim. it was rude of me to toy with you. In my defense, however, I
didn't realize your were retarded until quite late. I thought you were being
purposely dense.

jim, if you had your mind made up that you were going to spend two and half big
boat bux to buy a tiny increase in performance at some considerable increase in
maintenance, why in hell did you ask for people's opinions? It just made you
look stew ped. Which you have a right to do, of course. But why announce it
to the world?

From: Jim Richardson
Date: 9/4/2004 8:00 PM Eastern Daylight Time
Message-id:

On 04 Sep 2004 23:25:53 GMT,
Shen44 wrote:
ubject: What are the pros and cons of a folding prop?
From: "Jeff Morris"

If you insist on calling the Autoprop "feathering" then you have to admit
its
a
pretty poor one, having 5 to 10 times the drag of other feathering props.
For
example, in the MIT/Practical Sailor test, at about 7 knots the Autoprop
had
10
pounds of drag, while the 2 and 3 blade Maxprop feathering props had about
1
and
2 pounds respectively. The folding props were so low they weren't shown.
10
pounds of drag is pretty good, compared to the 25 to 35 pounds for many of
the
props in the test, but it isn't the same as feathering. The Autoprop has
some
interesting properties, like very good performance in reverse, if you rev

From this, and looking at diagrams of both the "maxprop" and "autoprop", it
appears that both designs can rightly call themselves "feathering".
However, it appears that the design of the hub of the autoprop is such that
it
still creates a marked amount of drag which has little to do with the
shape/curvature of the blades.
Agree/disagree/comments?

Shen


Sounds about right to me, the autprop looks like it would produce
significantly more drag than the Max prop to me, and that both, would
produce less drag than a fixed. Since I think the autoprop is about the
same $$ as the Max prop, I'd go for the Max, unless there was some real
good reason otherwise. Maintenance maybe? is the Max prop a lot more
work to maintain?

--
Jim Richardson http://www.eskimo.com/~warlock
"`If there's anything more important than my ego around, I
want it caught and shot now.'"
-- Zaphod

On Sat, 04 Sep 2004 23:30:33 GMT, Jim Richardson
wrote:
the autoprop turns it's blades, to be parallel to the axis of the
shaft, resulting in less drag than in the fwd or reverse direction,.
How is that not feathering?

I an unfamiliar with the autoprop.If it turns its blades' angle of
attack to the near zero angle (actually slightly negative angle) that
minimizes drag, then this is said to be a feathering prop.
[one realises that a blade's angle varies with distance from the hub,
so that the idea of a fixed angle of attack is a slight abstraction]

If a prop system allows the blades to fold at the hub in order to
minimize drag this is usually described as a folding prop.

If a prop system allows the prop blades' angle of attack to vary so as
to maximize power transfer at the present water speed, this is said to
be a variable pitch prop system.

Let me ask Jim specifically (in order to avoid interjections from the
lunatic fringe) which of these three types of prop system he would
call the Autoprop?

Regards

Brian Whatcott Altus OK

Brian Whatcott wrote:

I an unfamiliar with the autoprop.If it turns its blades' angle of
attack to the near zero angle (actually slightly negative angle) that
minimizes drag, then this is said to be a feathering prop.
[one realises that a blade's angle varies with distance from the hub,
so that the idea of a fixed angle of attack is a slight abstraction]

If a prop system allows the blades to fold at the hub in order to
minimize drag this is usually described as a folding prop.

If a prop system allows the prop blades' angle of attack to vary so as
to maximize power transfer at the present water speed, this is said to
be a variable pitch prop system.

This may be a description for some. However, in my world, a "variable
pitch" prop starts at "zero" pitch (blades 90 deg to a "feathered"
position) and to increase speed, pitch is increased. These are also
called controllable pitch props and they ( normally ) can not be
"feathered".
However, it appears from the literature on the autoprop/maxprop, there
may be a degree of "variable" to these props ..... I'm mentioning this
here, as it does appear there is room for confusion.

otn


Let me ask Jim specifically (in order to avoid interjections from the
lunatic fringe) which of these three types of prop system he would
call the Autoprop?

Regards

Brian Whatcott Altus OK

"JAXAshby" wrote in message
...
10% of max boat speed = 1/3 knot??

The "1/3 of a knot" was an average over a wide range of conditions. Actually,
at the 7.5 knots where it had 70 pounds of drag, the loss was .8 knots, over
10%. I would think that many sailors would consider eliminating this drag
would be significant. Obviously, you don't. Perhaps if you sailed more, you
would.



That one heap slow mutha boat.

I'm reading from the Jan 1,1995 article "MIT Propeller Test - Part 2." The
Michigan Wheel 3-blade had about 70 pounds drag at 8 knots. This is a huge
amount of drag, costing maybe 10% of boat speed. The earlier article (Oct 1,
'93) had the same numbers plus a discussion on how much speed this would
cost.
They predicted 1/3 of a knot improvement, averaged over a wide variety of
conditions, for a 25 foot boat when removing a 3 blade prop.

I'd agree with some of your conclusions, especially that a folding prop is
perhaps not useful for the OP's Westsail. Since a 2-blade fixed can be lined
up
in the aperture to minimize drag, there's little reason to sacrifice reverse
capability with a folder. I can't imagine trying to "crash stop" a Westsail
with a poor performing prop.

However, this is not true for a lot of boats. Many fin keel boats have the
prop
too far from the keel to benefit from lining it up. Boats with Saildrives
don't
have that option. Light weight boats that rely on low drag would be affected
worse by a high drag prop. And catamarans, with two props would have double
the
drag with fixed props.




"JAXAshby" wrote in message
...
jeff, are you sure of that 25 to 35 pound figure at 7 knots? I recall 170#
at
5 knots.

35# at 7 knots is only about 3/4 hp. not worth thinking about.

If you insist on calling the Autoprop "feathering" then you have to admit
its
a
pretty poor one, having 5 to 10 times the drag of other feathering props.
For
example, in the MIT/Practical Sailor test, at about 7 knots the Autoprop
had
10
pounds of drag, while the 2 and 3 blade Maxprop feathering props had about
1
and
2 pounds respectively. The folding props were so low they weren't shown.
10
pounds of drag is pretty good, compared to the 25 to 35 pounds for many of
the
props in the test, but it isn't the same as feathering. The Autoprop has
some
interesting properties, like very good performance in reverse, if you rev
it
up.


"Jim Richardson" wrote in message
...
On 04 Sep 2004 13:08:18 GMT,
JAXAshby wrote:
Then why did you post a definition of feathering, which fit the
autoprop?

it does not fit. not even close. and if you had not blown $2,200 on
a
prop
hoping against hope you could make your boat *sail* faster you would
know
the
difference.

Did the dealer tell you you could pass Island Packets and Westsail 32
if
you
bought an auto-prop?



I didn't buy one JAXAshby. I simply wanted to know what you meant by
calling it a non-feathering prop. Alas, I should have known better than
to expect rational discourse from you.

--
Jim Richardson http://www.eskimo.com/~warlock
'Windows' really does make a fine swear word, representing all that's
taboo and awful - just like '****', '****', etc."
-- Mark Hughes, sdm

"JAXAshby" wrote in message
...
jeffies, a boat under sail has one hell of a lot more drag than a boat
motoring
in a flat calm.

And how is this relevant to anything?



also, keep in mind that the boat under discussion is a Westsail 32, a boat
usually having a minimum of 30 hp installed, and often 40+ hp.

A Westsail 32 with a 10 to 12 hp engine installed is unmarketable. One would
need one hell of a lot patience to wait for wind and tide before setting off.

Are you claiming that an aux engine is always run at an rpm that produces its
full rated power? Most boaters understand that a diesel might only produce half
its rated output at cruise speed. For example, a Yanmar 3YM is rated at 29 HP
only delivers about 14 to the prop at 2800 rpm.

Although the OP has a Westsail, he asked what other boaters have experienced, so
the discussion is about all boats. As I said elsewhere, I think the Westsail
would benefit less than other boats from a low drag prop.






keep in mind that props don't drag all that much anyway. according to the
MIT
data, even a fixed 3 blade only pulled 170# on a boat at 5 knots, or about
the
equivelent of 2-1/2 hp.


That's not much drag??? That's roughly the drag from a 25 knot breeze!
Are
you saying that this would have no affect on boat speed?

Are you claiming that a having a 2.5 hp engine pulling backwards would have
little affect on speed? At the low RPMs many boats use to go 5 knots, they
only
use 10 to 12 hp to go forward

Mr. Jax,
Could you kindly explain what this answer is supposed to mean?
We are waitng.
Matt Colie

JAXAshby wrote:
jeffies, a boat under sail has one hell of a lot more drag than a boat motoring
in a flat calm.

jeffies, **you** claimed it only takes 10 or 12 hp to push a Westsail 32 at
five knots. remember? nah, I am sure you don't remember anything from more
than 7 hours ago.

From: "Jeff Morris"
Date: 9/4/2004 11:11 PM Eastern Daylight Time
Message-id:

"JAXAshby" wrote in message
...
jeffies, a boat under sail has one hell of a lot more drag than a boat
motoring
in a flat calm.

And how is this relevant to anything?



also, keep in mind that the boat under discussion is a Westsail 32, a boat
usually having a minimum of 30 hp installed, and often 40+ hp.

A Westsail 32 with a 10 to 12 hp engine installed is unmarketable. One
would
need one hell of a lot patience to wait for wind and tide before setting
off.

Are you claiming that an aux engine is always run at an rpm that produces its
full rated power? Most boaters understand that a diesel might only produce
half
its rated output at cruise speed. For example, a Yanmar 3YM is rated at 29
HP
only delivers about 14 to the prop at 2800 rpm.

Although the OP has a Westsail, he asked what other boaters have experienced,
so
the discussion is about all boats. As I said elsewhere, I think the Westsail
would benefit less than other boats from a low drag prop.






keep in mind that props don't drag all that much anyway. according to
the
MIT
data, even a fixed 3 blade only pulled 170# on a boat at 5 knots, or
about
the
equivelent of 2-1/2 hp.


That's not much drag??? That's roughly the drag from a 25 knot breeze!
Are
you saying that this would have no affect on boat speed?

Are you claiming that a having a 2.5 hp engine pulling backwards would
have
little affect on speed? At the low RPMs many boats use to go 5 knots,
they
only
use 10 to 12 hp to go forward

jeffies, 70# at 7.5 knots = 1.6 hp. are you saying that a Westsail 32 sailing
in winds heavy enough to make the boat go 7.5 can motor just as fast with a 16
hp engine?

yeah, that is what you are saying whether you know it or not.

From: "Jeff Morris"
Date: 9/4/2004 10:49 PM Eastern Daylight Time
Message-id:

"JAXAshby" wrote in message
...
10% of max boat speed = 1/3 knot??

The "1/3 of a knot" was an average over a wide range of conditions.
Actually,
at the 7.5 knots where it had 70 pounds of drag, the loss was .8 knots, over
10%. I would think that many sailors would consider eliminating this drag
would be significant. Obviously, you don't. Perhaps if you sailed more, you
would.



That one heap slow mutha boat.

I'm reading from the Jan 1,1995 article "MIT Propeller Test - Part 2."
The
Michigan Wheel 3-blade had about 70 pounds drag at 8 knots. This is a
huge
amount of drag, costing maybe 10% of boat speed. The earlier article (Oct
1,
'93) had the same numbers plus a discussion on how much speed this would
cost.
They predicted 1/3 of a knot improvement, averaged over a wide variety of
conditions, for a 25 foot boat when removing a 3 blade prop.

I'd agree with some of your conclusions, especially that a folding prop is
perhaps not useful for the OP's Westsail. Since a 2-blade fixed can be
lined
up
in the aperture to minimize drag, there's little reason to sacrifice
reverse
capability with a folder. I can't imagine trying to "crash stop" a
Westsail
with a poor performing prop.

However, this is not true for a lot of boats. Many fin keel boats have
the
prop
too far from the keel to benefit from lining it up. Boats with Saildrives
don't
have that option. Light weight boats that rely on low drag would be
affected
worse by a high drag prop. And catamarans, with two props would have
double
the
drag with fixed props.




"JAXAshby" wrote in message
...
jeff, are you sure of that 25 to 35 pound figure at 7 knots? I recall
170#
at
5 knots.

35# at 7 knots is only about 3/4 hp. not worth thinking about.

If you insist on calling the Autoprop "feathering" then you have to
admit
its
a
pretty poor one, having 5 to 10 times the drag of other feathering
props.
For
example, in the MIT/Practical Sailor test, at about 7 knots the
Autoprop
had
10
pounds of drag, while the 2 and 3 blade Maxprop feathering props had
about
1
and
2 pounds respectively. The folding props were so low they weren't
shown.
10
pounds of drag is pretty good, compared to the 25 to 35 pounds for many
of
the
props in the test, but it isn't the same as feathering. The Autoprop
has
some
interesting properties, like very good performance in reverse, if you
rev
it
up.


"Jim Richardson" wrote in message
...
On 04 Sep 2004 13:08:18 GMT,
JAXAshby wrote:
Then why did you post a definition of feathering, which fit the
autoprop?

it does not fit. not even close. and if you had not blown $2,200
on
a
prop
hoping against hope you could make your boat *sail* faster you
would
know
the
difference.

Did the dealer tell you you could pass Island Packets and Westsail
32
if
you
bought an auto-prop?



I didn't buy one JAXAshby. I simply wanted to know what you meant by
calling it a non-feathering prop. Alas, I should have known better
than
to expect rational discourse from you.

--
Jim Richardson http://www.eskimo.com/~warlock
'Windows' really does make a fine swear word, representing all
that's
taboo and awful - just like '****', '****', etc."
-- Mark Hughes, sdm