Question about prop and shaft rotations... we have twin engines with
counter rotational engines, 1 clockwise, 1 counter clockwise.... we also
have a LH prop and a RH prop currently not on the shafts... thus the
question...

Trying to confirm that a clockwise turning shaft in forward gear needs a LH
prop and thus a TH prop would go on a counter-clockwise turning shaft in
forward gear... can someone confirm my thoughts???

Thanks for any and all responses... and no I am not the one who removed the
props and failed to record which one came off which side...

My understanding from what I've read ... RH=clockwise and
LH=counterclockwise ... the opposite to your thoughts. At least it's real
easy to find out, and to correct if you get it wrong the first time.

"Tony Abbott" wrote in message
om...
Question about prop and shaft rotations... we have twin engines with
counter rotational engines, 1 clockwise, 1 counter clockwise.... we also
have a LH prop and a RH prop currently not on the shafts... thus the
question...

Trying to confirm that a clockwise turning shaft in forward gear needs a
LH
prop and thus a TH prop would go on a counter-clockwise turning shaft in
forward gear... can someone confirm my thoughts???

Thanks for any and all responses... and no I am not the one who removed
the
props and failed to record which one came off which side...

Subject: Prop Question
From: "Tony Abbott"

Question about prop and shaft rotations... we have twin engines with
counter rotational engines, 1 clockwise, 1 counter clockwise.... we also
have a LH prop and a RH prop currently not on the shafts... thus the
question...

Trying to confirm that a clockwise turning shaft in forward gear needs a LH
prop and thus a TH prop would go on a counter-clockwise turning shaft in
forward gear... can someone confirm my thoughts???

Thanks for any and all responses... and no I am not the one who removed the
props and failed to record which one came off which side...

Typicaly, the RH prop goes on the stbd side (clockwise rotation when viewed
from the rear) and the LH goes on the port side (counter clockwise rotation
when view from the rear).
Look on the trannies, there maybe a lable that tells you which way they rotate.

Capt. Bill

On Tue, 21 Sep 2004 23:41:39 GMT, "Tony Abbott"
wrote:

Question about prop and shaft rotations... we have twin engines with
counter rotational engines, 1 clockwise, 1 counter clockwise.... we also
have a LH prop and a RH prop currently not on the shafts... thus the
question...

Trying to confirm that a clockwise turning shaft in forward gear needs a LH
prop and thus a TH prop would go on a counter-clockwise turning shaft in
forward gear... can someone confirm my thoughts???

Thanks for any and all responses... and no I am not the one who removed the
props and failed to record which one came off which side...

Assuming that you can do this, turn the motors over and look at the
rotation. The RH prop should go on the starboard side and the LH prop
should go on the port side. Which, when you think about it, makes
sense.

Which brings up an interesting question.

What if the RH rotating engine was on the port side and vice verse.
Would there be any change in performance?

Just curious.

Later,

Tom
-----------
"Angling may be said to be so
like the mathematics that it
can never be fully learnt..."

Izaak Walton "The Compleat Angler", 1653

Tony Abbott wrote:
Question about prop and shaft rotations... we have twin engines with
counter rotational engines, 1 clockwise, 1 counter clockwise.... we also
have a LH prop and a RH prop currently not on the shafts... thus the
question...

Trying to confirm that a clockwise turning shaft in forward gear needs a LH
prop and thus a TH prop would go on a counter-clockwise turning shaft in
forward gear... can someone confirm my thoughts???

Thanks for any and all responses... and no I am not the one who removed the
props and failed to record which one came off which side...



Depends on where you view it from obviously, the usual thing is to view
it from "aft" (that's the back Harry)

Viewed from aft a right-hand propeller turns clockwise & left-hand
anticlockwise.

This causes confusion because some/most engine manufacturers, even
today describe the engine's rotation when viewed from forward (that's
the front Harry) i.e. an engine described as having left hand rotation
at it's output by "some" engine suppliers, will need a right hand
propeller (ask Gould, giggles all round here at the time; amateurs
buying from & then spruiking/spamming for other amateurs:-)). So with
your question Tony, make sure you know which engine "output shaft" turns
clockwise etc viewed from aft!!!!, the output shaft obviously turns in
the same diection as the prop (hopefully:-)), regardless of how the
engine rotation is described. (no point simplifying for Harry & his
tribe of simpletons wouldn't get this not ever, too uneducated &
basically stupid)

With counter rotating twins the preferred setup is to have the right
handed prop (clockwise viewed from aft) on the starboard side (that's
the right hand side of the boat Harry) & the left handed prop
(anticlockwise viewed from aft) on the port side (that's the left hand
side of the boat Harry)

This means that counter rotating twins should have the props turning
out away from each other at the top. So prop walk can be harvested to
advantage when maneuvering (it behaves like a wheel, at the bottom of
the prop the water is denser than the top, imagine Harry upside down).

Say trying to spin the boat to starboard with twins the starboard,
right handed prop (now turning anticlockwise from aft in reverse gear)
will try to walk the stern across towards port, the port left handed
prop (also turning anticlockwise from aft still in forward gear) will
also be trying to walk the stern to port, so even if the boat stays
almost stationary, it will assist the bow to swing to starboard. (again
no attempt to help Harry & his thugs, they're still working on the port
& starboard thing:-) no no seriously for a minute, are your elections
sort of a nation wide IQ test??? it certainly seems that way if you look
at rec.boats, the lib voters are the uneducated winers & the repubs are
the ones who take care of the real things & thankfully for me, the rest
of the free world)

K

K. Smith wrote:
Tony Abbott wrote:
Question about prop and shaft rotations... we have twin engines with
counter rotational engines, 1 clockwise, 1 counter clockwise.... we also
have a LH prop and a RH prop currently not on the shafts... thus the
question...

Trying to confirm that a clockwise turning shaft in forward gear needs a LH
prop and thus a TH prop would go on a counter-clockwise turning shaft in
forward gear... can someone confirm my thoughts???

Thanks for any and all responses... and no I am not the one who removed the
props and failed to record which one came off which side...



Depends on where you view it from obviously, the usual thing is to view
it from "aft" (that's the back Harry)



Wow...you got another couple days off for taking your meds, eh?




--
We today have a president of the United States who looks like he is the
son of Howdy Doody or Alfred E. Newman, who isn't smarter than either of
them, who is arrogant about his ignorance, who is reckless and
incompetent, and whose backers are turning the United States into a pariah.

What, me worry?

With counter rotating twins the preferred setup is to have the right
handed prop (clockwise viewed from aft) on the starboard side (that's
the right hand side of the boat Harry) & the left handed prop
(anticlockwise viewed from aft) on the port side (that's the left hand
side of the boat Harry)

This means that counter rotating twins should have the props turning
out away from each other at the top. So prop walk can be harvested to
advantage when maneuvering (it behaves like a wheel, at the bottom of
the prop the water is denser than the top, imagine Harry upside down).

Say trying to spin the boat to starboard with twins the starboard,
right handed prop (now turning anticlockwise from aft in reverse gear)
will try to walk the stern across towards port, the port left handed
prop (also turning anticlockwise from aft still in forward gear) will
also be trying to walk the stern to port, so even if the boat stays
almost stationary, it will assist the bow to swing to starboard. K





The above is basicly correct... but not the full story.
The navy tend to put props on the other way around because props turning
inwards towards each other at the top is more efficient
This is done on the basis that navy ships have tugs etc to assist manouvers
in port.. so they trade the manouverability for better efficiency at speed.
When all is said and done, you will have to fit the props to suit the
engines/gearboxes as fitted to the boat unless you wanna swap them round?

The above is basicly correct... but not the full story.
The navy tend to put props on the other way around because props turning
inwards towards each other at the top is more efficient
This is done on the basis that navy ships have tugs etc to assist manouvers
in port.. so they trade the manouverability for better efficiency at speed.
When all is said and done, you will have to fit the props to suit the
engines/gearboxes as fitted to the boat unless you wanna swap them round

Add to this, most Navy surface combatants (not sure about carriers, though
doubt it) use variable pitch props, which throws in a whole other set of
handling characteristics .... some can do a credable twin screw

Shen

Aft looking forward, it is the direction of the top of the shaft.


"Tony Abbott" wrote in message
om...
Question about prop and shaft rotations... we have twin engines with
counter rotational engines, 1 clockwise, 1 counter clockwise.... we also
have a LH prop and a RH prop currently not on the shafts... thus the
question...

Trying to confirm that a clockwise turning shaft in forward gear needs a
LH
prop and thus a TH prop would go on a counter-clockwise turning shaft in
forward gear... can someone confirm my thoughts???

Thanks for any and all responses... and no I am not the one who removed
the
props and failed to record which one came off which side...

On Tue, 21 Sep 2004 23:41:39 GMT, "Tony Abbott"
wrote:

Question about prop and shaft rotations... we have twin engines with
counter rotational engines, 1 clockwise, 1 counter clockwise.... we also
have a LH prop and a RH prop currently not on the shafts... thus the
question...

Trying to confirm that a clockwise turning shaft in forward gear needs a LH
prop and thus a TH prop would go on a counter-clockwise turning shaft in
forward gear... can someone confirm my thoughts???

Thanks for any and all responses... and no I am not the one who removed the
props and failed to record which one came off which side...


Here is your difficulty: a clockwise turning shaft, looking forward,
is a counter clockwise turning shaft, looking aft.
For aircraft certainly, the convention is to use the pilot's view,
looking forward, to decide which direction a prop is turning.

Anyway, looking forward, a prop shaft turning clockwise takes a prop
which turns clockwise in forward gear.

Perhaps it would help you to consider a regular wood screw. These are
screwed clockwise. So if you set the point of a wood screw forwards,
the edges of the screw are angled in the same direction as a RH prop.
The head of a woodscrew turns clockwise to screw into wood, and a
RH prop turns clockwise to screw forwards into water.

Clear as mud? I thought so!

Brian W