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

On 07 Jun 2004 10:48:32 GMT, (JAXAshby) wrote:

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.


Yes, all these things are right ones.

Question is: How has been designed (engineered) the Thrust Bearings Box ?

(sorry I don't know its English code-name)

Our ones are designed and manufactured with a couple of Heavy-Duty Taper Rolling Bearings, # 322xx, a couple of Rubber
Seals for Lube and Water Cooling devices.

Used in Clam Dredgers working in Reverse... they are tailored to be operating in both directions.

Heavy-Duty Bearings in Forward and Light-Dutry ones in Reverse were used times when Bearings were very expensive... but
actually it is a "poor" spare, requiring different machining on both sides, double the Stocks of spares on shelves and
aboard.

But they could be till existing...

Glad to have meet someone involved in Technical matter.

I'm a newcomer in this NG but I will visit it at least once a week.

I hope to have some interesting questions to put to NG attention.


Thank you for your time,

WinXP.

fair winds, guy. As you point out, if the tranny is designed to take a prop
going either direction things are fine.

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.


Yes, all these things are right ones.

Question is: How has been designed (engineered) the Thrust Bearings Box ?

(sorry I don't know its English code-name)

Our ones are designed and manufactured with a couple of Heavy-Duty Taper
Rolling Bearings, # 322xx, a couple of Rubber
Seals for Lube and Water Cooling devices.

Used in Clam Dredgers working in Reverse... they are tailored to be operating
in both directions.

Heavy-Duty Bearings in Forward and Light-Dutry ones in Reverse were used
times when Bearings were very expensive... but
actually it is a "poor" spare, requiring different machining on both sides,
double the Stocks of spares on shelves and
aboard.

But they could be till existing...

Glad to have meet someone involved in Technical matter.

I'm a newcomer in this NG but I will visit it at least once a week.

I hope to have some interesting questions to put to NG attention.


Thank you for your time,

WinXP.

Thanks for all your replies.

I've cleared things up this much:

The transmission is designed to run equally fine in both directions. Ratios
are almost similar. The transmission has two "modes" - A and B. A is the
"normal" mode where the propeller-shaft runs in opposite direction of the
engine. B is normally reverse - the propeller-shaft runs same way as the
engine.

Here's the funny thing: From the factory, the boat is delivered with a LH
propeller - which means that the transmission has to run in the "B"-position
to have the boat move forward - i.e. reverse of "normal"!

I called the Norwegian factory to ask why. They replied that "the boat liked
the LH propeller the most"! (Don't know what that means.)

So it all narrows down to this: Assuming that transmission is not an issue -
are there any "hull-issues" that should imply that a given hull simply "runs
better" with a LH instead of a RH - or vice versa?

Anders
Denmark



"JAXAshby" skrev i en meddelelse
...
fair winds, guy. As you point out, if the tranny is designed to take a
prop
going either direction things are fine.

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.


Yes, all these things are right ones.

Question is: How has been designed (engineered) the Thrust Bearings Box ?

(sorry I don't know its English code-name)

Our ones are designed and manufactured with a couple of Heavy-Duty Taper
Rolling Bearings, # 322xx, a couple of Rubber
Seals for Lube and Water Cooling devices.

Used in Clam Dredgers working in Reverse... they are tailored to be
operating
in both directions.

Heavy-Duty Bearings in Forward and Light-Dutry ones in Reverse were used
times when Bearings were very expensive... but
actually it is a "poor" spare, requiring different machining on both
sides,
double the Stocks of spares on shelves and
aboard.

But they could be till existing...

Glad to have meet someone involved in Technical matter.

I'm a newcomer in this NG but I will visit it at least once a week.

I hope to have some interesting questions to put to NG attention.


Thank you for your time,

WinXP.

Assuming that transmission is not an issue -
are there any "hull-issues" that should imply that a given hull simply "runs
better" with a LH instead of a RH - or vice versa?

Anders
Denmark

I've lost track of the boat in question. The issue could well involve
"operator" ease or senses such as the steering station location to the side,
which can be a factor when docking.
Some people just have a "feel" that a particular rotation works better or feels
better to them

The boat in question is a 33 feet semiplaning motorboat. Controls/rudder to
the starboard as well as seating arrangment. Engine Yanmar 6LP-STE,
transmission Hurth HWS 630 A

Anders

I've lost track of the boat in question. The issue could well involve
"operator" ease or senses such as the steering station location to the
side,
which can be a factor when docking.
Some people just have a "feel" that a particular rotation works better or
feels
better to them

On Mon, 7 Jun 2004 23:03:19 +0200, "Anders Lassen" anders.lassenNEJTILSPAM (at)adr.dk wrote:

Thanks for all your replies.

I've cleared things up this much:

The transmission is designed to run equally fine in both directions. Ratios
are almost similar. The transmission has two "modes" - A and B. A is the
"normal" mode where the propeller-shaft runs in opposite direction of the
engine. B is normally reverse - the propeller-shaft runs same way as the
engine.

Here's the funny thing: From the factory, the boat is delivered with a LH
propeller - which means that the transmission has to run in the "B"-position
to have the boat move forward - i.e. reverse of "normal"!

I called the Norwegian factory to ask why. They replied that "the boat liked
the LH propeller the most"! (Don't know what that means.)

So it all narrows down to this: Assuming that transmission is not an issue -
are there any "hull-issues" that should imply that a given hull simply "runs
better" with a LH instead of a RH - or vice versa?

Anders
Denmark


Yes, it is.

Venetian Gondola is operated by a "single" oar in the RH side: to go straight it is shaped asymmetrical.

The LH side is more curved than the RH side.

Oar turns to left... shaped side turns to right... = straight line.

Same thing happens to a single propeller boat: the reaction to propeller rotation tries to turn boat to right or to lift
direction.

To go straight forward you have to compensate time by time.

To avoid this any Boat Designer has an its own "trick"... maybe a different shape of the hull... maybe a slight
"off-center" centerline... maybe a different tank in one side... maybe battery pack.. maybe something else...

It could be "calculated" or it could have been found during the first tests of the boat...

Right now we are "blueprinting" several propellers for an all new power boat that doesn't wish to plane...

Of course for the Boat Manufacturer is cheaper to replace several propellers than get away a full set of boat moulds...

This is the way: Test... no good... modify... test... no good... replace... test... maybe... adjust a bit.. test... go!

Cheer!

WinXP

"JAXAshby" wrote in message
...

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.


Either I am not following what you are saying or I am envisioning something
totally different.

As you said, the thrust on the shaft must be countered someplace, and that
someplace is the thrust bearing(s). The thrust will either "push" or
"pull", it shouldn't matter which direction the shaft is rotating.

If you attempted to drive the boat by having the propeller in front, like an
airplane, then the shaft will be pulling and the thrust bearing surface
associated with "pull" will bear the brunt of the load. But I didn't think
this is what we were talking about.

I know that several models of Velvet Drive transmissions don't care which
direction the input and output shafts turn, as long as they turn the same
direction in "forward". You can have a Left Hand and Right Hand rotating
engine turning Left Hand and Right Hand props and the transmissions don't
care. If you attempted to have the Left Hand engine turn the Right Hand
prop, however, then the transmission would be using the "reverse" clutch for
forward which is not nearly as robust as the "forward" clutch and you would
likely have reliability issues.

The web page for the Hurth transmissions indicated that many of their models
were capable of full engine horsepower in either "forward" or "reverse"
operation. I don't know if that really means you can use them for reversing
the rotation for counter rotation or not.

There are many outdrive designs that has the drive shaft come down and drive
two gears, one towards the front and one towards the rear. A "dog" or cone
clutch will engage one gear or the other, which will make the prop shaft
turn one way or the other. The clutches are identical and the thrust is
carried on the shaft bearing (not the gears) so it doesn't matter if the
gear more towards the front is considered "forward" or not.

Rod

On Mon, 7 Jun 2004 14:52:14 -0700, "Rod McInnis" wrote:


"JAXAshby" wrote in message
...

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.


Either I am not following what you are saying or I am envisioning something
totally different.

As you said, the thrust on the shaft must be countered someplace, and that
someplace is the thrust bearing(s). The thrust will either "push" or
"pull", it shouldn't matter which direction the shaft is rotating.

If you attempted to drive the boat by having the propeller in front, like an
airplane, then the shaft will be pulling and the thrust bearing surface
associated with "pull" will bear the brunt of the load. But I didn't think
this is what we were talking about.

I know that several models of Velvet Drive transmissions don't care which
direction the input and output shafts turn, as long as they turn the same
direction in "forward". You can have a Left Hand and Right Hand rotating
engine turning Left Hand and Right Hand props and the transmissions don't
care. If you attempted to have the Left Hand engine turn the Right Hand
prop, however, then the transmission would be using the "reverse" clutch for
forward which is not nearly as robust as the "forward" clutch and you would
likely have reliability issues.

The web page for the Hurth transmissions indicated that many of their models
were capable of full engine horsepower in either "forward" or "reverse"
operation. I don't know if that really means you can use them for reversing
the rotation for counter rotation or not.

There are many outdrive designs that has the drive shaft come down and drive
two gears, one towards the front and one towards the rear. A "dog" or cone
clutch will engage one gear or the other, which will make the prop shaft
turn one way or the other. The clutches are identical and the thrust is
carried on the shaft bearing (not the gears) so it doesn't matter if the
gear more towards the front is considered "forward" or not.

Rod


Hi Rod.

You are right... we are right else.

All problems are regarding: what kind of Transmission you are reversing.

Clutches and Gearbox::

Good HD ones have same clutch for Forward and Reverse.
Some ones have not... so Forward has to be forward, engaging only two gears.
So it requires a propeller rotating reverse than engine.

Reverse has Three Gears and the central one (idler) is a very small one, rotating on a small Roller Bearing or
equivalent one.
Gear Ratio between Driven Gear and Idler Gear (the small one) is usually in the ratio of 3:1

This is meaning that with boat engine rotating at 2,000 rpm the Idler Gear is rotating at 6.000 rpm!
With boat engine rotating at 4.000 rpm... Idle Gear is rotating at 12,000 rpm !

(By the way: Why Transmission Gearboxes are using Oil Coolers?)

So best solution for twin engines boat is to have one engine RH and one LH.

So best solution to "reverse" propeller... is to replace Engine !!!

Bevel Gear Gearbox has no problem to rotate Forward or Reverse... but they are on Outboards...

Thrust Bearing:

Old ones or cheap ones are assembled with two different Thrust Bearings: Heavy Duty for Forward, Light Duty for
Reverse...

Good new ones have Two identical HD Thrust Bearings both for Forward and for Reverse... so no matter in which direction
they are mainly operated (not rotating)..

You are right else: Forward is always Forward... no matter is RH or LH...

There has been a bit of confusing details. Sorry for this.

Bye,

WinXP