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

Subject: Propeller rotation - important? - Yes, it is.
From: "Anders Lassen" anders.lassenNEJTILSPAM(at)adr.dk
Date: 06/08/2004 12:23 Pacific Standard Time
Message-id:

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

May be part of the reason. Since you have a controls/steering to stbd, you will
get the best view during docking when docking stbd side too.
For a single screw boat with the LH prop, docking is normally much easier when
docking stbd side rather than port side too, as Good Ole Mr. propwalk will tend
to pull your stern into the dock when backing.

Shen

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