OK, tell us what you mean by stopped. Then tell us about the Titanic's
engineering plant and how they would have "stopped" the central shaft.


Nav wrote:
The engine would be stopped by opening the steam bypass valve. That
might not stop the propellor but that's not the issue here.

Please tell me what ships you've steamed where the engine could be
stopped by "opening a steam bypass valve." Also please tell me where the
steam is bypassed to... are you suggesting dumping main steam directly
into the condenser?

Another point I'd like you to explain is how do you stop the engine and
not the shaft. Push in the clutch, maybe?


Now are you still saying that stopping the engine has no effect on
rudder effectiveness

No, I'm saying that 1- a ship running at full speed is not going to stop
& lock the shaft in less than a minute, 2- if it did then the water flow
over the rudder would still be quite strong (ie 20+ knots), 3- in the
specific case of the Titanic, the central prop had no reverse and thus
no way to stop the shaft. Did you pay any attention at all to my post
explaining some of the basics of the Olympic class ships propulsion plant?



Do you know what slip is

Yes.


... and how it would affect the rudder?

Sure. Is it supposed to be rocket science? Are you insisting that a ship
going 20+ knots is suddenly not going to answer her helm because of the
loss of the prop stream?

It has been suggested that if the Titanic's central prop had been spun
in reverse, the cavitation would have greatly diminished her steering
response... now that is a stronger case, except that it's simply not
possible when there's no reverse on the central engine.



... What would
have been a likely value of slip for the central propellor of the
Titanic at full speed?

I don't know, but it wouldn't be hard to figure out. The stats for the
engine's RPM and prop pitch are public.



It's strange but every time I've taken the helm of a displacement boat
the loss of helm authority when the engine is throttled back has been
most obvious.

Yes, and I'm sure you have lots and lots of experience driving 800+
ships at 20+ knots. They handle *very* differently than a sailboat with
under auxiliary power.

If you're claiming that a vessel cannot be steered without a prop stream
over the rudder, then how do you manage to control your boat's heading
when under sail?



.... Perhaps it's your engineering expertise that makes the
difference.

Perhaps.

DSK

DSK wrote:

OK, tell us what you mean by stopped. Then tell us about the
Titanic's engineering plant and how they would have "stopped" the
central shaft.


Nav wrote:

The engine would be stopped by opening the steam bypass valve. That
might not stop the propellor but that's not the issue here.


Please tell me what ships you've steamed where the engine could be
stopped by "opening a steam bypass valve." Also please tell me where the
steam is bypassed to... are you suggesting dumping main steam directly
into the condenser?


On the Titanic the turbine received LP steam from the main engines. To
stop it separate from the main engines, a valve which I call a "steam
bypass valve" was opened to bypass the turbine and allow the LP steam
back to the condenser.

It is strange that you claimed such expertise on the Titanic machinery
but did not know this.

Cheers

Please tell me what ships you've steamed where the engine could be
stopped by "opening a steam bypass valve." Also please tell me where
the steam is bypassed to... are you suggesting dumping main steam
directly into the condenser?


Nav wrote:
On the Titanic the turbine received LP steam from the main engines.

Duh. I told you that several posts ago, Navjax.

.... To
stop it separate from the main engines, a valve which I call a "steam
bypass valve" was opened to bypass the turbine and allow the LP steam
back to the condenser.

The inlet to the central turbine was actually under a slight vacuum. It
wouldn't be "LP steam" it was exhaust from the wing engines. And in
order to *stop* the central turbine, it's steam inlet would have to be shut.

Then what happens?
hint- consider the relationship between the seawater inlet temp to the
condenser (termed "injection") and the condensing pressure of steam
going into the condenser.


It is strange that you claimed such expertise on the Titanic machinery
but did not know this.

Strange that you are now repeating my posts, ignoring proper
terminology, and basically showing total ignorance of steam propulsion
engineering, while insisting that somehow I'm the one that's wrong.
Actually, it's more funny than strange, and also par for the course.

DSK

DSK wrote:

Please tell me what ships you've steamed where the engine could be
stopped by "opening a steam bypass valve." Also please tell me where
the steam is bypassed to... are you suggesting dumping main steam
directly into the condenser?


Nav wrote:

On the Titanic the turbine received LP steam from the main engines.


Duh. I told you that several posts ago, Navjax.


Wow I'm impressed! You are a veritable font of information on this
thread aren't you?

.... To stop it separate from the main engines, a valve which I call a
"steam bypass valve" was opened to bypass the turbine and allow the LP
steam back to the condenser.


The inlet to the central turbine was actually under a slight vacuum.


Yopu can wriggle as much as you want but your self serving posturing is
clearly exposed. The inlet to the turbine was not sub atmospheric.

It
wouldn't be "LP steam" it was exhaust from the wing engines. And in
order to *stop* the central turbine, it's steam inlet would have to be
shut.

Wot no bypass valve? Where did the steam go Doug -into the vacuum at the
tubine inlet? Bwhahahahhahaha!! You are such a clown. The inlet pressure
was 9psi -it's on all the web sites describing the engineering -or are
they wrong too?

Cheers

wouldn't be "LP steam" it was exhaust from the wing engines. And in
order to *stop* the central turbine, it's steam inlet would have to be
shut.


Nav wrote:
Wot no bypass valve? Where did the steam go Doug -into the vacuum at the
tubine inlet? Bwhahahahhahaha!! You are such a clown. The inlet pressure
was 9psi -it's on all the web sites describing the engineering -or are
they wrong too?

Actually, they are. The design (according to Harlan & Wolff, who should
know) called for inlet to the turbine at ~ 11 psia. So, if you grant
them 9psi *a* then they're not far wrong. Or are you now going to claim
that the condenser ran at 3 psi ... even back then, hotwell pressure was
usually given in mmHg... hint hint...

DSK

DSK wrote:

wouldn't be "LP steam" it was exhaust from the wing engines. And in
order to *stop* the central turbine, it's steam inlet would have to
be shut.



Nav wrote:

Wot no bypass valve? Where did the steam go Doug -into the vacuum at
the tubine inlet? Bwhahahahhahaha!! You are such a clown. The inlet
pressure was 9psi -it's on all the web sites describing the
engineering -or are they wrong too?


Actually, they are. The design (according to Harlan & Wolff, who should
know) called for inlet to the turbine at ~ 11 psia. So, if you grant
them 9psi *a* then they're not far wrong.


Holy backpedal!!!!!!!!!!!!!

Bwhahahhahaha

Cheers

.... The inlet
pressure was 9psi -it's on all the web sites describing the
engineering -or are they wrong too?



Actually, they are. The design (according to Harlan & Wolff, who
should know) called for inlet to the turbine at ~ 11 psia. So, if you
grant them 9psi *a* then they're not far wrong.


Nav wrote:
Holy backpedal!!!!!!!!!!!!!

Way to go, Navsprit.

I'm right, you're stuck, so you call me names, holler that I'm
backpedalling, and go bwahaha.

I suggest you look at some slightly more sophisticated sources of info.
Not that you'd understand them, but at least you could try.

DSK