Hi,

Recently my propeller threw off a blade. I ordered a new propeller from
Michigan and today it arrived.

BUT - my local dealer made a mistake: He ordered a right-hand propeller -
but the old one was a left hand rotation!

I just waited for four weeks - and really wouldn't like waiting another four
weeks for another to arrive. So here's my question: Is it possible to
reverse the direction of the transmission instead so I don't have to change
the propeller? The engine is a Yanmar 6LP-STE and the transmission is a
Hurth/ZF.

And: Should I do it? I mean - Is there any drawbacks in changing rotation?

Anders
Denmark

Cheaper to exchange the prop for the correct hand than to replace the
transmission.

Going to the opposite hand prop will also change the way your boat handles in
close quarters.

You can't find a used or loaner prop to get you by until the correct item
arrives?

I just have the impression that some marine gears are built to run both
ways - so that props in dual engine configurations can be made to turn in
opposite directions. In other words: I'm not talking about REPLACING the
transmission but changing the rotation by basically exchanging forward with
reverse...

...or is this nonsens...? :-)


Anders



"Gould 0738" skrev i en meddelelse
...
Cheaper to exchange the prop for the correct hand than to replace the
transmission.

Going to the opposite hand prop will also change the way your boat handles
in
close quarters.

You can't find a used or loaner prop to get you by until the correct item
arrives?

"Anders Lassen" anders.lassenNEJTILSPAM (at)adr.dk wrote in message
. ..

And: Should I do it? I mean - Is there any drawbacks in changing rotation?

Some transmissions, (as in some I/O units that I have had in the past) have
their forward and reverse gears/clutches identical. An example was a Volvo
I/O unit my dad had 30 years ago. You could move a part of the shift linkage
from the left side of the belcrank to the right side, swap the prop and
everything would be fine.

There are also a lot of transmissions where the forward and reverse circuits
are NOT equal. Velvet Drive transmissions are an example. The forward gear
is much more robust and more efficient. Reverse involves more gears and the
clutch is not anywhere near as robust.

If you are not sure that your transmission is happy with either direction
then you should not use the reverse pitch prop. I checked the Hurth web
site and found the following bit of information:

"These ratings allow full power through forward and reverse gear trains,
unless otherwise stated."

So, I believe the bottom line is that you need to check the model of your
transmission! Your best bet would be to contact Hurth directly:

http://zf-marine.com

If you can't get a satisfactory answer, I wouldn't risk it.

Rod

"Anders Lassen" anders.lassenNEJTILSPAM (at)adr.dk wrote in message
. ..

I just have the impression that some marine gears are built to run both
ways - so that props in dual engine configurations can be made to turn in
opposite directions. In other words: I'm not talking about REPLACING the
transmission but changing the rotation by basically exchanging forward
with
reverse...

..or is this nonsens...? :-)


Anders


Nope, not nonsense, but may not be true of all transmissions. My 52 foot
Navigator, powered by twin Volvo diesels is set up with one transmission
running in reverse, compared to the other transmission. I've forgotten the
transmission types, but they are made in Italy and are common on larger
boats and yachts.

Eisboch

My Volvo Penta 270 stern drive changes from R to L prop spin with a simple
change of the shifter rod and linkage. Don't know much about your engine
combo, though.


"Anders Lassen" anders.lassenNEJTILSPAM (at)adr.dk wrote in message
. ..
Hi,

Recently my propeller threw off a blade. I ordered a new propeller from
Michigan and today it arrived.

BUT - my local dealer made a mistake: He ordered a right-hand propeller -
but the old one was a left hand rotation!

I just waited for four weeks - and really wouldn't like waiting another
four
weeks for another to arrive. So here's my question: Is it possible to
reverse the direction of the transmission instead so I don't have to
change
the propeller? The engine is a Yanmar 6LP-STE and the transmission is a
Hurth/ZF.

And: Should I do it? I mean - Is there any drawbacks in changing rotation?

Anders
Denmark

On Tue, 25 May 2004 18:37:27 +0200, "Anders Lassen" anders.lassenNEJTILSPAM (at)adr.dk wrote:

Hi,

Recently my propeller threw off a blade. I ordered a new propeller from
Michigan and today it arrived.

BUT - my local dealer made a mistake: He ordered a right-hand propeller -
but the old one was a left hand rotation!

I just waited for four weeks - and really wouldn't like waiting another four
weeks for another to arrive. So here's my question: Is it possible to
reverse the direction of the transmission instead so I don't have to change
the propeller? The engine is a Yanmar 6LP-STE and the transmission is a
Hurth/ZF.

And: Should I do it? I mean - Is there any drawbacks in changing rotation?

Anders
Denmark






Hi Anders,

I hope it will be not too late for a reply to your question.

Rotation is not a your choice, but it is depending from the boat manufacturer designer.

You don't specify WHAT kind of transmission you are using, but presuming you own a classic one comprising an Engine, a
Marine Transmission, a Propeller Drive Shaft and a Propeller...

....you will have these problems...

It is depending from engine rotation (LH or RH), kind of transmission gear (LH or RH, Forward Ratio and Reverse Ratio,
Forward Torque and Reverse Torque, Internal Gears design etc.)

Some technical details:

Usually all engines are "LH" (seen from Flywheel side).

Usually Forward is "direct drive" meaning that there are only TWO gears engaged... so Rotation of Propeller Shaft is
inverted versus engine rotation ( LHRH=RH) ... so Propeller has to be RH .

Reverse is done by THREE Gears... so Engine and Transmission Shaft have same rotation ( LHRHLH=LH ) so a RH Propeller
rotates LH and does REVERSE.

Where is the matter?

You will have NEVER the same ratio Forward and Reverse:

Forward has TWO Gears coupled together and transfers a lot of power (direct drive).

Reverse has THREE Gears coupled together and the Second One is a small one rated (designed) for a limited Torque and
use.

So you cannot use "Transmission Reverse" for " Boat Forward".

So, if you wish to use a "Reverse Propeller" you have to replace ENGINE with a RH one!

Of course there are other options, but these are the most important ones.
+++

Otherwise... if you have another kind of transmission, and specifically the one with Forward and Reverse similar to the
one used on Outboards ( Three Bevel Gears Style with Cog Clutches ) there are no matters...

Forward and Reverse have same Ratio, same Torque, same Cog Clutch.... so RH or LH are optional choices and are not
involving any other part or performance...
+++

The answer is exclusively depending from the parts involved in.

I hope this could help you.

Regards,

WinXP


PS.- I don't know who-where is your Supplier... but any decent Supplier has "a lot" of used Propellers available for
speed tests or power test or saved or... so he "has to have" a decent one for emergency purpose...

Important is it has same HUB and same Rotation... Pitch, Outer Dia and number of Blades is relative...

By the way, it is a good idea to have a "replaceable" propeller on board...

the trust bearing is wrong.


anders.lassenNEJTILSPAM (at)adr.dk wrote:

Hi,

Recently my propeller threw off a blade. I ordered a new propeller from
Michigan and today it arrived.

BUT - my local dealer made a mistake: He ordered a right-hand propeller -
but the old one was a left hand rotation!

I just waited for four weeks - and really wouldn't like waiting another four
weeks for another to arrive. So here's my question: Is it possible to
reverse the direction of the transmission instead so I don't have to change
the propeller? The engine is a Yanmar 6LP-STE and the transmission is a
Hurth/ZF.

And: Should I do it? I mean - Is there any drawbacks in changing rotation?

Anders
Denmark






Hi Anders,

I hope it will be not too late for a reply to your question.

Rotation is not a your choice, but it is depending from the boat manufacturer
designer.

You don't specify WHAT kind of transmission you are using, but presuming you
own a classic one comprising an Engine, a
Marine Transmission, a Propeller Drive Shaft and a Propeller...

...you will have these problems...

It is depending from engine rotation (LH or RH), kind of transmission gear
(LH or RH, Forward Ratio and Reverse Ratio,
Forward Torque and Reverse Torque, Internal Gears design etc.)

Some technical details:

Usually all engines are "LH" (seen from Flywheel side).

Usually Forward is "direct drive" meaning that there are only TWO gears
engaged... so Rotation of Propeller Shaft is
inverted versus engine rotation ( LHRH=RH) ... so Propeller has to be RH .

Reverse is done by THREE Gears... so Engine and Transmission Shaft have same
rotation ( LHRHLH=LH ) so a RH Propeller
rotates LH and does REVERSE.

Where is the matter?

You will have NEVER the same ratio Forward and Reverse:

Forward has TWO Gears coupled together and transfers a lot of power (direct
drive).

Reverse has THREE Gears coupled together and the Second One is a small one
rated (designed) for a limited Torque and
use.

So you cannot use "Transmission Reverse" for " Boat Forward".

So, if you wish to use a "Reverse Propeller" you have to replace ENGINE with
a RH one!

Of course there are other options, but these are the most important ones.
+++

Otherwise... if you have another kind of transmission, and specifically the
one with Forward and Reverse similar to the
one used on Outboards ( Three Bevel Gears Style with Cog Clutches ) there are
no matters...

Forward and Reverse have same Ratio, same Torque, same Cog Clutch.... so RH
or LH are optional choices and are not
involving any other part or performance...
+++

The answer is exclusively depending from the parts involved in.

I hope this could help you.

Regards,

WinXP


PS.- I don't know who-where is your Supplier... but any decent Supplier has
"a lot" of used Propellers available for
speed tests or power test or saved or... so he "has to have" a decent one
for emergency purpose...

Important is it has same HUB and same Rotation... Pitch, Outer Dia and
number of Blades is relative...

By the way, it is a good idea to have a "replaceable" propeller on board...

On 07 Jun 2004 03:03:28 GMT, (JAXAshby) wrote:

the trust bearing is wrong.

snip


Hi.

It should be or should be not.

It is depending from "direction" not "rotation":

"Forward" is always forward so Propeller is always "pushing" the vessel.

Usually is the "Propeller Shaft" to be supporting the pushing efforts.

Gears and Clutches are supporting only the rotational torques.

But in any way has to be examined the specific Driveline, application and purpose.

Same thing for Gearbox engineering, drawing, performance and manufacturer technical choices...

By the way in North Adria Sea and Lagoon of Venice all Clam Dredgers are operating in Reverse !

So a lot of fishermen are replacing rotation of Propeller just to operate Gearbox in "Forward"...

.... other ones are "preferring" to operate in true Reverse as so the gear-ratio is wider than Forward one...

In any way it is a good thing don't operate DIY on ANY vital parts of any kind ofvessel...


Bye,


WinXP

ah, you just might wish to remember that the prop MUST push against the prop
shaft which pushes against the thrust bearing to push the boat forward. Got
to.

In other words, the thrust bearing takes 100% of the horsepower developed by
the engine. That is a lot. In forward.

There is also a thrust bearing needed for going in reverse as well. However,
as the horsepower used in reverse is much less and the time it is used is
hugely less the reverse thrust bearing need not be anywhere near as big.

Now, change the prop so the former reverse thrust bearing becomes the new
forward thrust bearing and operates at 100% power over extended time the
potential to trash that bearing becomes very real.

Most people forget that the prop has to push against something to push the boat
forward. That something is the thrust bearing.

the trust bearing is wrong.

snip


Hi.

It should be or should be not.

It is depending from "direction" not "rotation":

"Forward" is always forward so Propeller is always "pushing" the vessel.

Usually is the "Propeller Shaft" to be supporting the pushing efforts.

Gears and Clutches are supporting only the rotational torques.

But in any way has to be examined the specific Driveline, application and
purpose.

Same thing for Gearbox engineering, drawing, performance and manufacturer
technical choices...

By the way in North Adria Sea and Lagoon of Venice all Clam Dredgers are
operating in Reverse !

So a lot of fishermen are replacing rotation of Propeller just to operate
Gearbox in "Forward"...

... other ones are "preferring" to operate in true Reverse as so the
gear-ratio is wider than Forward one...

In any way it is a good thing don't operate DIY on ANY vital parts of any
kind ofvessel...


Bye,


WinXP