brian, an Auto-Prop fits you definition #3

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

Time for the meds again, jaxie. Your reading comprehension is failing. I made
no claim of the Westsail, I said "At the low RPMs many boats use to go 5 knots,
they only use 10 to 12 hp to go forward." Are you claiming that a Westsail is
representative of "many boats"?

If fact, I already said several times that I didn't think a low drag prop would
help a Westsail that much, but they could be of value to many other boats.
You've been claiming that they are useless for any boat other than a high
performance racer. Since you lost that argument, you're now backpedaling and
misrepresenting my comments. Typical lying from cowardly jaxie.

But, since you brought it up, how much power does a Westsail actually use? At
5 knots, that is a "Speed to Length" ratio of 0.95 (where the 7 knot hull speed
would be 1.34). To achieve that speed, a displacement boat will have 1400
pounds per HP. At 20,000 pounds, the Westsail uses about 14.2 HP. A bit
higher than the "10 to 12" I mentioned for "many boats," but most 32 footers
don't weigh anywhere near 10 tons. How much wind is needed to generate 14 hp
on a Westsail? With 650 square feet of sail, assuming 0.02 HP/sq.ft. at 14
knots wind, this is 13 HP; so it looks like about 15 to 16 knots of wind is
needed to get a Westsail up to 5 knots.





"JAXAshby" wrote in message
...
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

I made no such claims for a Westsail, which after all, has a hull speed of 7
knots.

Although the original poster has a Westsail, most of us don't. You opened this
discussions to all boats when you claimed (in your first post in this thread):

You will definitely will see a decent speed improvement under sail with a
folding prop

no, you won't. folding props only hve value for racing boats

The truth is that the very article you (mis)quoted said that the predicted speed
loss from a 3 blade prop was an average of 1/3 knot, over a wide range of
conditions, up to 0.8 knots at higher speed. Since appendage resistance goes up
with the square of speed, this is clearly a larger issue for lighter boats that
are often around hull speed with smaller rigs.



"JAXAshby" wrote in message
...
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

In "Jeff Morris" writes:

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.


There are good props and bad props in folding and unfolding category.
A good folding prop is better on reverse (and thus in stopping) as a bad
fixed prop. I have tried it, when I lost my folding prop (GORI) and had
to settle for a fixed one with equal diamerer and pitch. Wit my folding
prop there was never any trouble in reversing or stopping the boat, the
fixed one could not get me out from a berth against a 25 knot breeze.

- Lauri Tarkkonen

mattie, it is self obvious. boats motoring go in a straight line (more or
less). boats bent over sailing don't. also boats motoring a flat calm have
limited amount of windage to overcome, while a Westsail 32 sailing 7.5 knots is
in one of hell of a blow and has one hell of a lot of windage to overcome.

mattie? ever been on a sailboat?

From: Matt Colie
Date: 9/5/2004 9:21 AM Eastern Daylight Time
Message-id:

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, the discussion has from the start been about a Westsail 32. ask your
wife to reread the posts for you.

From: "Jeff Morris"
Date: 9/5/2004 10:55 AM Eastern Daylight Time
Message-id:

Time for the meds again, jaxie. Your reading comprehension is failing. I
made
no claim of the Westsail, I said "At the low RPMs many boats use to go 5
knots,
they only use 10 to 12 hp to go forward." Are you claiming that a Westsail
is
representative of "many boats"?

If fact, I already said several times that I didn't think a low drag prop
would
help a Westsail that much, but they could be of value to many other boats.
You've been claiming that they are useless for any boat other than a high
performance racer. Since you lost that argument, you're now backpedaling and
misrepresenting my comments. Typical lying from cowardly jaxie.

But, since you brought it up, how much power does a Westsail actually use?
At
5 knots, that is a "Speed to Length" ratio of 0.95 (where the 7 knot hull
speed
would be 1.34). To achieve that speed, a displacement boat will have 1400
pounds per HP. At 20,000 pounds, the Westsail uses about 14.2 HP. A bit
higher than the "10 to 12" I mentioned for "many boats," but most 32 footers
don't weigh anywhere near 10 tons. How much wind is needed to generate 14
hp
on a Westsail? With 650 square feet of sail, assuming 0.02 HP/sq.ft. at 14
knots wind, this is 13 HP; so it looks like about 15 to 16 knots of wind is
needed to get a Westsail up to 5 knots.





"JAXAshby" wrote in message
...
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, if folding/feathering/kinda twisting props increased performance by
your claimed 10% ALL new boats would have them installed at the factory.

duh.

From: "Jeff Morris"
Date: 9/5/2004 10:55 AM Eastern Daylight Time
Message-id:

Time for the meds again, jaxie. Your reading comprehension is failing. I
made
no claim of the Westsail, I said "At the low RPMs many boats use to go 5
knots,
they only use 10 to 12 hp to go forward." Are you claiming that a Westsail
is
representative of "many boats"?

If fact, I already said several times that I didn't think a low drag prop
would
help a Westsail that much, but they could be of value to many other boats.
You've been claiming that they are useless for any boat other than a high
performance racer. Since you lost that argument, you're now backpedaling and
misrepresenting my comments. Typical lying from cowardly jaxie.

But, since you brought it up, how much power does a Westsail actually use?
At
5 knots, that is a "Speed to Length" ratio of 0.95 (where the 7 knot hull
speed
would be 1.34). To achieve that speed, a displacement boat will have 1400
pounds per HP. At 20,000 pounds, the Westsail uses about 14.2 HP. A bit
higher than the "10 to 12" I mentioned for "many boats," but most 32 footers
don't weigh anywhere near 10 tons. How much wind is needed to generate 14
hp
on a Westsail? With 650 square feet of sail, assuming 0.02 HP/sq.ft. at 14
knots wind, this is 13 HP; so it looks like about 15 to 16 knots of wind is
needed to get a Westsail up to 5 knots.





"JAXAshby" wrote in message
...
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

yup, jeffies, every last boat manufacturer purposely reduces the performance of
its products by purposely installed those cruddy, huge drag inducing fixed
blade props. Why? Because, of course, they want to sell the suckers who
bought their boats to buy even bigger boats.

yeah, right, jeffies.


From: "Jeff Morris"
Date: 9/5/2004 11:14 AM Eastern Daylight Time
Message-id:

I made no such claims for a Westsail, which after all, has a hull speed of 7
knots.

Although the original poster has a Westsail, most of us don't. You opened
this
discussions to all boats when you claimed (in your first post in this
thread):

You will definitely will see a decent speed improvement under sail with a
folding prop

no, you won't. folding props only hve value for racing boats

The truth is that the very article you (mis)quoted said that the predicted
speed
loss from a 3 blade prop was an average of 1/3 knot, over a wide range of
conditions, up to 0.8 knots at higher speed. Since appendage resistance goes
up
with the square of speed, this is clearly a larger issue for lighter boats
that
are often around hull speed with smaller rigs.



"JAXAshby" wrote in message
...
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

I'd have to agree that there are good and bad props. I'd also agree that
reverse performance is not necessarily poor with a good folder. I have two
Volvo folding props on my catamaran and I've had little problem in reverse. But
then, I have two diesels and the boat is under 10,000 pounds.

On the MIT/Practical Sailor test for reverse thrust, the Gori ranked somewhat
better than the Martec folder, but substantially worse than almost all of the
other props. At a given rpm, the folders only had a third to a half of the
thrust as the fixed props that were tested. I suppose there could be a fixed 2
blade that's worse than the Gori, but its pretty clear there are some that are
much better in reverse.



"Lauri Tarkkonen" wrote in message
...
In "Jeff Morris"
writes:

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.


There are good props and bad props in folding and unfolding category.
A good folding prop is better on reverse (and thus in stopping) as a bad
fixed prop. I have tried it, when I lost my folding prop (GORI) and had
to settle for a fixed one with equal diamerer and pitch. Wit my folding
prop there was never any trouble in reversing or stopping the boat, the
fixed one could not get me out from a berth against a 25 knot breeze.

- Lauri Tarkkonen

I've had little problem in reverse. But
then, I have two diesels

jeffies, your props don't give a rat's what fuel your engines burn. In fact,
your props are totally unable to determine what fuel your engines use.

so, pray tell, why do **you** think your props can tell the difference.