My brother in law, and I have had a discussion of whether it
is best - from a pure speed point of view (no consideration
to the mechanics/oil/maintenance/gearbox etc. here ...)
whether you should let your "fixed three bladed propeller"
run/turn or keep it fixed (like put into gear) when sailing
just for the wind with your sails in a 34 feet cruiser
weighing roughly 5 T ... We have - unsuccesfully - tried to
find out using the log ... the results were not conclusive -
or one of us would not admit, that the other was right ... I
think we need a testimony from someone, that has a
'scientific based valid answer' ... or just knows for sure
....

The assumption is: There is no way to move, turn, 'collapse'
anything on the propeller - the 'blades' are fixed ... (hard
to explain in a language, that is not your own ... hope you
get my point).

Anybody in this group that can convince one of us, that he
is not right? ...

--
Flemming Torp

It has been repeatedly demonstrated that airplanes glide significantly
farther (up to 20%) when the nose is raised to slow them down enough
to stop the prop and best glide speed is then resumed. I can't see
any reason why this wouldn't be true of boat propellers as well. It
also agrees with just about every other reference I've seen on the
subject.

--

Roger Long



"Flemming Torp" fletopkanelbolle2rp.danmark wrote in message
. ..
My brother in law, and I have had a discussion of whether it is
best - from a pure speed point of view (no consideration to the
mechanics/oil/maintenance/gearbox etc. here ...) whether you should
let your "fixed three bladed propeller" run/turn or keep it fixed
(like put into gear) when sailing just for the wind with your sails
in a 34 feet cruiser weighing roughly 5 T ... We have -
unsuccesfully - tried to find out using the log ... the results were
not conclusive - or one of us would not admit, that the other was
right ... I think we need a testimony from someone, that has a
'scientific based valid answer' ... or just knows for sure ...

The assumption is: There is no way to move, turn, 'collapse'
anything on the propeller - the 'blades' are fixed ... (hard to
explain in a language, that is not your own ... hope you get my
point).

Anybody in this group that can convince one of us, that he is not
right? ...

--
Flemming Torp

"Flemming Torp" fletopkanelbolle2rp.danmark wrote in message
. ..
My brother in law, and I have had a discussion of whether it
is best - from a pure speed point of view (no consideration
to the mechanics/oil/maintenance/gearbox etc. here ...)
whether you should let your "fixed three bladed propeller"
run/turn or keep it fixed (like put into gear) when sailing

I always put the transmission in reverse when sailing. I don't
think that my Yanmar book says anything, but when I sailed on a
friend's Cape Dory, he said to always do so due the gearbox
that he had.

Leanne

"Leanne" skrev i en meddelelse
...

"Flemming Torp" fletopkanelbolle2rp.danmark wrote in
message
. ..
My brother in law, and I have had a discussion of whether
it
is best - from a pure speed point of view (no
consideration
to the mechanics/oil/maintenance/gearbox etc. here ...)
whether you should let your "fixed three bladed
propeller"
run/turn or keep it fixed (like put into gear) when
sailing

I always put the transmission in reverse when sailing. I
don't
think that my Yanmar book says anything, but when I sailed
on a
friend's Cape Dory, he said to always do so due the
gearbox
that he had.

Leanne



So do I - when cruising, but that is not my point ...
The question is: (If I race for instance): Will I increase
the speed of the boat by letting the propeller turn without
resistance? Or should I stop it from turning?

--
Flemming Torp

"Flemming Torp" fletopkanelbolle2rp.danmark wrote in message . ..

"Leanne" skrev i en meddelelse
...

"Flemming Torp" fletopkanelbolle2rp.danmark wrote in
message
. ..
My brother in law, and I have had a discussion of whether
it
is best - from a pure speed point of view (no
consideration
to the mechanics/oil/maintenance/gearbox etc. here ...)
whether you should let your "fixed three bladed
propeller"
run/turn or keep it fixed (like put into gear) when
sailing

I always put the transmission in reverse when sailing. I
don't
think that my Yanmar book says anything, but when I sailed
on a
friend's Cape Dory, he said to always do so due the
gearbox
that he had.

Leanne



So do I - when cruising, but that is not my point ...
The question is: (If I race for instance): Will I increase
the speed of the boat by letting the propeller turn without
resistance? Or should I stop it from turning?

--
Flemming Torp


It's a fact that a spinning prop creates far more drag
that a stopped prop.

CN

There is no easy way to prove this one way or the other by hand waving
for one reason: it depends on the propeller. Large ship propellers
are sometimes more efficient freewheeling, but this is not the case
for 3-blade yacht props. I suspect the the difference has to do with
the pitch, and whether or not the flow is stalled - Ship props often
high a large pitch compared to yacht props.

BTW, it worth while lining up one blade of a 3-blade with the hull
when you lock it.



Flemming Torp wrote:
My brother in law, and I have had a discussion of whether it
is best - from a pure speed point of view (no consideration
to the mechanics/oil/maintenance/gearbox etc. here ...)
whether you should let your "fixed three bladed propeller"
run/turn or keep it fixed (like put into gear) when sailing
just for the wind with your sails in a 34 feet cruiser
weighing roughly 5 T ... We have - unsuccesfully - tried to
find out using the log ... the results were not conclusive -
or one of us would not admit, that the other was right ... I
think we need a testimony from someone, that has a
'scientific based valid answer' ... or just knows for sure
...

The assumption is: There is no way to move, turn, 'collapse'
anything on the propeller - the 'blades' are fixed ... (hard
to explain in a language, that is not your own ... hope you
get my point).

Anybody in this group that can convince one of us, that he
is not right? ...

"Flemming Torp" fletopkanelbolle2rp.danmark wrote in
:

Anybody in this group that can convince one of us, that he
is not right? ...



Let the boat drive the prop when sailing. That shaft produces 15-25A of DC
power on Lionheart from her shaft-driven alternator. No sense wasting good
power draggin' a stalled prop behind you. Lionheart's Perkins 4-108
transmission has been freewheeling because of her shaft alternator since
1986. Doesn't seem to have hurt it a bit.

Look over in alt.binaries.pictures.sports.ocean at the engine room on
Lionheart under the center cockpit. The shaft alternator is driven by a
flat belt from a large pulley on the shaft. At 8 knots, the special
alternator, itself, is turning about 200 RPM. To get the engine started,
you must turn off the excitation current to this shaft alternator so you
can remove the keyring from its switch to move the keyring to the engine
control panel to crank the diesel. This makes sure you have secured the
shaft alternator before starting the engine....captain proof.

"Larry W4CSC" wrote
Look over in alt.binaries.pictures.sports.ocean at the engine room
on
Lionheart under the center cockpit. (snip) This makes sure you have
secured the
shaft alternator before starting the engine....captain proof.


Gee, isn't this kind of "niggling and perfectionist", to quote a well
respected rec.boats contributor?

Of course, there is nothing wrong with that

--

Roger Long

"Roger Long" wrote in
:

Gee, isn't this kind of "niggling and perfectionist", to quote a well
respected rec.boats contributor?


Oh, you'd have a fit if you looked into that bilge. There's dishwater,
some oil, some rust, a few tools too deep to reach even with the magnet,
how awful! It's a boat....not house beautiful. Everything from the sinks,
shower, everything but the head, dumps in her bilge to be pumped overboard
WITHOUT those nasty thru-hull fittings rotting away...(c;

Look at the next picture. This is the NEW engine Cap bought from a guy in
NC I met on this newsgroup. It's a pullout. See? We didn't even paint
it! Looks awful...runs fantastic. The original looked worse. It had over
8000 hours on it. This "new" one is only up to 900 hours, now. Cap'n
Geoffrey couldn't even destroy it trying to start it full of seawater when
that stupid water injection line to the dripless packing he had a shipyard
install BACKED UP seawater into the exhaust ports. Try sailing up Ponce
Inlet S of Daytona Beach in the rush of an outgoing tide past the
lighthouse and seawall so the tow operator can drag you all the way to
Daytona Marina. Scary stuff that day. Cutter Doc did a great job pickling
the engine. It looked like we pumped the Exxon Valdez oil slick out of the
crankcase...(c;

These pictures are old. I need to carry my camera down, now that she's
been fitted out, and take some new pictures in her. I'm usually too busy
when Geoffrey is around working on his to-do list...(c; He finally gave up
trying to pay me. He asked what I wanted for all my work. I told him,
"That's easy. Just take me with you." It's worked out great for both of
us....(c;

I'm sory, but I can only see one picture in
alt.binaries.pictures.sports.ocean ... Am I missing
something?

--
Flemming Torp



"Larry W4CSC" skrev i en meddelelse
...
"Roger Long" wrote in
:

Gee, isn't this kind of "niggling and perfectionist", to
quote a well
respected rec.boats contributor?


Oh, you'd have a fit if you looked into that bilge.
There's dishwater,
some oil, some rust, a few tools too deep to reach even
with the magnet,
how awful! It's a boat....not house beautiful.
Everything from the sinks,
shower, everything but the head, dumps in her bilge to be
pumped overboard
WITHOUT those nasty thru-hull fittings rotting away...(c;

Look at the next picture. This is the NEW engine Cap
bought from a guy in
NC I met on this newsgroup. It's a pullout. See? We
didn't even paint
it! Looks awful...runs fantastic. The original looked
worse. It had over
8000 hours on it. This "new" one is only up to 900 hours,
now. Cap'n
Geoffrey couldn't even destroy it trying to start it full
of seawater when
that stupid water injection line to the dripless packing
he had a shipyard
install BACKED UP seawater into the exhaust ports. Try
sailing up Ponce
Inlet S of Daytona Beach in the rush of an outgoing tide
past the
lighthouse and seawall so the tow operator can drag you
all the way to
Daytona Marina. Scary stuff that day. Cutter Doc did a
great job pickling
the engine. It looked like we pumped the Exxon Valdez oil
slick out of the
crankcase...(c;

These pictures are old. I need to carry my camera down,
now that she's
been fitted out, and take some new pictures in her. I'm
usually too busy
when Geoffrey is around working on his to-do list...(c;
He finally gave up
trying to pay me. He asked what I wanted for all my work.
I told him,
"That's easy. Just take me with you." It's worked out
great for both of
us....(c;