the drag of fixed props at
low speeds is not that great.

yup.

but that is the market feathering props aim at. at the high end, just a teeny
bit more sail pushes the boat faster than you wanna go anyway.



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

Some salesman might have tried to sell you on low speed performance because
he
knew you were scared of high performance boats, but the drag of fixed props
at
low speeds is not that great. Its only really significant at higher speeds.
As
everyone else knows, appendage drag goes up with the square of speed.

Perhaps you can show us even one folding/feathering manufacturer's site that
claims the primary advantage is a low speed.


"JAXAshby" wrote in message
...
btw, jeffies, what everyone else is fully aware of and you are totally
ignorant
of is that folding/feathering prop manufacturers promote their products'
value
at ---- low ---- wind speeds, not high speeds.

duh.


From: "Jeff Morris"
Date: 9/5/2004 3:09 PM Eastern Daylight Time
Message-id:

jaxie, even my cat understands that you changed the thread by claiming the
folders "only have value for racing boats." Now that you've been proven
wrong
on that, you're backpedaling as fast as you can. Don't hurt yourself.



"JAXAshby" wrote in message
...
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