DSK wrote:


In the case of the Titanic at the time frame between sighting and
collision..... IF they had started to reduce steam to the turbine prior
to reversing the recips, this measured reduction while the other engines
were going full, would/should have created a "disturbance" aft of that
center prop which would/should have reduced the effectiveness of that
single, center rudder.

Yes, but I'm not sure they would have done that. The reciprocating
engines could be reversed with the throw of a lever... the valve gear
control. However there is no definite knowledge of what bells were rung,
when, and how long it took the engineers to answer them. Nor is there
definite knowledge of how long a warning time between sighting the 'berg
and hitting it... the oft-quoted 37 seconds is a figure calculated by
the American Inquiry board from som fairly vague data.

This becomes an engineering question and I'm not an engineer. However,
considering the mass involved, I'd assume that the process for reversing
engines running at full sea speeds (even recips) would involve a good
deal more than just "throwing a lever" G



If the steam to the turbine was cut off and the central prop left to
freewheel, then the rudder would have lost some effectiveness... but if
the prop was engaged in reverse (which the Titanic's couldn't be anyway)
then it would be far worse.

Would require another turbine, but agreed.


Now, since I can see another route to your question. If the ship was
steaming along (different scenario) at full speed with no steam to the
turbine (it's just "freewheeling") would this reduce effectiveness of
the rudder? I would have to say yes, as it becomes a rotating drag which
, in my opinion, has to create disturbed water aft of the prop, which
has to disturb the "smooth" flow of water across the rudder.

Agreed. But I'm saying it would be less than if the prop were engaged in
reverse, or stopped & locked.

True

Without specific test which address the many various conditions and
actions that where or would occur, you have to assume that the above is
speculation on my part based on my own sense of what has happened when
handling one or two ships. G I.E., I don't guarantee I'm
right....these are my observations.

Well, if you're interested there is a lot of data to look at
http://www.titanicinquiry.org/
has both American and British inquiries and all the testimony.

G I've been through much of this in the past, so I've forgotten many
of the specifics, but remember there being many unanswered questions
since their knowledge base was relatively new at the time.
One thing that sticks in my mind was that the turbine received it's
steam from the main recip's which is why I thought they would need to
secure this engine prior to maneuvering the others .....could very well
be wrong here.
At any rate, I'm a firm believer that the Titanic could have benefited
from today's technology on rudders, not only in size but in shape and
location (Hate a twin screw with single rudder).

otn

otnmbrd wrote:
This becomes an engineering question and I'm not an engineer.

Maybe, but you're a lot more of an engineer than Navvie.

... However,
considering the mass involved, I'd assume that the process for reversing
engines running at full sea speeds (even recips) would involve a good
deal more than just "throwing a lever" G

Oh yeah, it would take a bit of time and some applied skill at the
lever. You *could* just throw it into full reverse, but it would be
dangerous.

I assume commercial ships don't practice stop-and-lock or crashback
drills like a military ship does.

A stop-and-lock on a turbine plant takes a bit less skill, since all you
have to do is shut of steam on the ahead throttle and crack open the
astern throttle, then slowly open it further. Less things to break, too.
There's the risk of losing vacuum on the condenser (there are far fewer
stages in the reverse turbine) which I assume would not be the case for
a normal recip plant; but would be a potential hazard with the Titanic
because of diverting steam from the central turbine.

When the ship is going slower, it's a lot easier.


If the steam to the turbine was cut off and the central prop left to
freewheel, then the rudder would have lost some effectiveness... but
if the prop was engaged in reverse (which the Titanic's couldn't be
anyway) then it would be far worse.


Would require another turbine, but agreed.

Right... some people think you just hit the clutch and shift into "R"
apparently.




Well, if you're interested there is a lot of data to look at
http://www.titanicinquiry.org/
has both American and British inquiries and all the testimony.


G I've been through much of this in the past, so I've forgotten many
of the specifics, but remember there being many unanswered questions
since their knowledge base was relatively new at the time.

Didn't you used to participate in the alt.history.ocean-liners.titanic
newsgroup? That was an interesting bunch. I seem to recall you and a
couple of other old salts discussing the issue of bringing the
Californian alongside the Titanic.

Anyway, imho the Inquiries are the best primary source of info about the
collision & sinking.


At any rate, I'm a firm believer that the Titanic could have benefited
from today's technology on rudders, not only in size but in shape and
location (Hate a twin screw with single rudder).

Well, her hull was shaped much like the previous generation of sailing
ships. The aft sections would have to be shaped quite differently to
have twin rudders. But Olypmic & Titanic were goreous ships... they
looked like tremendous yachts to my eye.

Regards
Doug King

DSK wrote:

otnmbrd wrote:

This becomes an engineering question and I'm not an engineer.


Maybe, but you're a lot more of an engineer than Navvie.

... However, considering the mass involved, I'd assume that the
process for reversing engines running at full sea speeds (even recips)
would involve a good deal more than just "throwing a lever" G


Oh yeah, it would take a bit of time and some applied skill at the
lever. You *could* just throw it into full reverse, but it would be
dangerous.

Skill at the lever. I love it. Don't you know the main engine valve
train was steam operated?

I assume commercial ships don't practice stop-and-lock or crashback
drills like a military ship does.

A stop-and-lock on a turbine plant takes a bit less skill, since all you
have to do is shut of steam on the ahead throttle and crack open the
astern throttle, then slowly open it further.

Good lord.

For those that have no idea about this here's a site:

http://www.tpub.com/content/fc/14104/css/14104_122.htm

Judge the depth of the Doug BS for yourself!

Cheers

Nav wrote:
Skill at the lever. I love it. Don't you know the main engine valve
train was steam operated?

You don't have a clue.

The main engine pilot valves were controlled by a lever which determined
the timing. The position of the lever controlled the duration & timing
of steam admitted to the cylinders and could be set from full power
ahead to full power astern. This was a standard set-up on recip steam
engines.



A stop-and-lock on a turbine plant takes a bit less skill, since all
you have to do is shut of steam on the ahead throttle and crack open
the astern throttle, then slowly open it further.


Good lord.

For those that have no idea about this here's a site:

http://www.tpub.com/content/fc/14104/css/14104_122.htm

Judge the depth of the Doug BS for yourself!

Please quote the section which you think proves I am BSing. Also, please
quote any references you have saying that the Titanic had clutches. Or
reduction gears, for that matter.

DSK

DSK wrote:

Nav wrote:

Skill at the lever. I love it. Don't you know the main engine valve
train was steam operated?


You don't have a clue.

The main engine pilot valves were controlled by a lever which determined
the timing. The position of the lever controlled the duration & timing
of steam admitted to the cylinders and could be set from full power
ahead to full power astern. This was a standard set-up on recip steam
engines.



A stop-and-lock on a turbine plant takes a bit less skill, since all
you have to do is shut of steam on the ahead throttle and crack open
the astern throttle, then slowly open it further.



Good lord.

For those that have no idea about this here's a site:

http://www.tpub.com/content/fc/14104/css/14104_122.htm

Judge the depth of the Doug BS for yourself!


Please quote the section which you think proves I am BSing. Also, please
quote any references you have saying that the Titanic had clutches. Or
reduction gears, for that matter.


C'mon my little fish, you know that you were referring to other turbine
plants -it could not be otherwise unless your decription of a reversing
throtle applies to thne Titanic. OR are you now saying the Titanic had a
reversing throttle?

Man do you love painting yourself into a corner! I guess you don't know
about reversing gears, clutches and CPP's as common ways to give astern
propulsion. OR are you saying all turbine powered ships have a reversing
turbine!

Bwhahahhaha

Cheers

DSK wrote:

Nav wrote:

Skill at the lever. I love it. Don't you know the main engine valve
train was steam operated?


You don't have a clue.

The main engine pilot valves were controlled by a lever which determined
the timing. The position of the lever controlled the duration & timing
of steam admitted to the cylinders and could be set from full power
ahead to full power astern. This was a standard set-up on recip steam
engines.



No, it's you that is full of it. The valve gear was so massive it could
not be moved by hand. Hence my pointing out the steam servo system.

Cheers

DSK wrote:



A stop-and-lock on a turbine plant takes a bit less skill, since all you
have to do is shut of steam on the ahead throttle and crack open the
astern throttle, then slowly open it further. Less things to break, too.

You would not disengage the main gearbox? Do you think the main turbine
gets spun backwards by the reversing turbine? Two other common methods
are CPP and clutches with reversing gears (the clutches are particularly
interesting from an engineering aspect).

Cheers

A stop-and-lock on a turbine plant takes a bit less skill, since all
you have to do is shut of steam on the ahead throttle and crack open
the astern throttle, then slowly open it further. Less things to
break, too.

Nav wrote:
You would not disengage the main gearbox?

How?

... Do you think the main turbine
gets spun backwards by the reversing turbine?

In most turbine powered ships, yes. The propulsion plant is a locked train.


... Two other common methods
are CPP and clutches with reversing gears (the clutches are particularly
interesting from an engineering aspect).

For what kind of plants? AFAIK clutches are quite rare on steam powered
ships. Diesels, yes... provided they aren't using variable pitch props.

DSK

Nav wrote:


DSK wrote:



A stop-and-lock on a turbine plant takes a bit less skill, since all
you have to do is shut of steam on the ahead throttle and crack open
the astern throttle, then slowly open it further. Less things to
break, too.


You would not disengage the main gearbox? Do you think the main turbine
gets spun backwards by the reversing turbine? Two other common methods
are CPP and clutches with reversing gears (the clutches are particularly
interesting from an engineering aspect).

Cheers

In my experience, with pure steam turbine plants, if you are at "sea
speeds", to stop the HP turbine you first have to pull out the extra
nozzles, then shut down the steam, then open the "guarding valve", and
when the shaft has stopped or nearly so, you can start cracking steam to
the LP turbine .... not the quickest of procedures.
There are no clutches or methods to disengage the main gearbox
(reduction gears).
For direct drive diesel (majority of ships nowadays) there are no
clutches or reversing gears.

otn

otnmbrd wrote:

In my experience, with pure steam turbine plants, if you are at "sea
speeds", to stop the HP turbine you first have to pull out the extra
nozzles, then shut down the steam, then open the "guarding valve", and
when the shaft has stopped or nearly so, you can start cracking steam to
the LP turbine .... not the quickest of procedures.
There are no clutches or methods to disengage the main gearbox
(reduction gears).

Steamboats have not used manually controlled nozzles for many years. The
modern turbine throttle valve uses a lifting beam to sequentially lift a
set of nozzle valves in the steam chest. A hydraulic cylinder lifts the
beam under control of the console throttle lever or wheel in maneuvering
mode or an electronic speed control when at sea speed.

The guardian valve may be operated remotely at the console and may be
selected to open when the throttle is moved astern. The engine does not
have to be stopped before opening the astern throttle and crash stops
are routinely performed after majopr maintenance or shipyard work on the
control system.

Rick