otnmbrd wrote:

Some comments interspersed

DSK wrote:

DSK the marine propulsion expert wrote:

In any case, the ship was going full speed, the loss of the prop
stream across the rudder would not reduce the rudder's effectiveness
very much.


This is probably most notable, in my experience, with variable pitch
props, but you can and will experience it with fixed pitch. You slow the
rpm of the prop and it tends to mess a bit with the smooth flow of
water past the rudder, reducing effectiveness until hull speed reduces
to rpm speed. (personal observation).


Yep, my point exactly. Wonder why he's never noticed it?

Cheers






Nav wrote:

http://www.dellamente.com/titanic/engines5.htm



Interesting web site. Thanks for the link.

It does contain a number of inaccuracies, though.


"Regardless, most scenarios agree steam to the turbine would have
been cut off. While this had little effect on the ship's forward motion,



???

The central turbine was about 35% ~ 40% of the ships forward power.
How is it going to have "little effect on the ship's forward motion?"

Or do they mean that shutting off steam to the turbine would not have
produced significant stopping impulse? That would be much more correct.


They might be thinking that the mass of the ship will keep things moving
with a gradual reduction in speed, not readily apparent in the time
frame of this collision.


They also don't appear to know how the reciprocating engines were
reversed.


... it deprived the rudder of the steady, forceful stream of water
necessary to turn a ship of that size.



???

A steady stream of water goin 22 + knots is not "forceful"?


It's forceful, but definitely not as forceful



... Several sources claim the rudder on the Titanic and her sister
ships was too small. If that was indeed the case, shutting down the
center turbine would be the last thing you would want to do in an
emergency."



The "rudder too small" claim is total malarkey. The Olympic was the
same design and had a long service career, with a reputation of being
a good handling ship.


Disagree. Rudder technology has come a long way. Although I don't doubt
that the ships may have been considered good handling by many of the
day, there are many possibilities which could have improved the
"overall" rudder effectiveness, though whether this could have saved the
day, is pure conjecture.



Hmm, seems to agree with me?



Sure. It's incorrect and based on assumptions when accurate data is
readily available.

Speaking of which, have you worked out the prop slip for the Olympic
class ships yet? Data readily available, all you need is the prop
pitch, top speed, and top speed rpm.


Slip is a variable ..... changes from day to day, based on a number of
factors.


... My yacht steers well without propwash because it's rudder, in
comparison, is huge... My point is that, most power vessels can have
much smaller rudders because they use the propwash to significantly
increase rudder effectiveness. It's standard naval architecture.



At low speed, sure. At full speed, the prop stream does increase
rudder effectiveness but I'd say that it's not "significant."
Judgement call, I guess... certainly your vast experience in handling
large steam ships and your claimed naval architect training give you a
big advantage here.

DSK


Would disagree. Prop wash is a very important contributor to rudder
effectiveness at all speeds .... put a ship's engine on "stop" ....
trust me, your effectiveness decreases rapidly.

otn

That's about all folks. I'm getting pretty tired of Navvie's BS.

Nav wrote:
Ok you asked for it:

Nav:
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?

So, here you are quoting yourself making several wrong claims, with a
bwahaha and calling names besides.



DSK:
Actually, they are. The design (according to Harlan & Wolff, who should
know) called for inlet to the turbine at ~ 11 psia.

Know what this "~" means?


... 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... "

So you didn't get the hint, have no clue what Rick & I have been talking
about.

Now you pretend that you never claimed the exhaust and the condenser
aren't under vacuum, along with shirking all the other bogus statements
you've made.



Kblam!

Is that the sound of you dropping what few marbles you used to have on
the floor? Goodbye, Navsprit.

Cheers!
DSK

DSK wrote:

Nav wrote:

Yes. http://www.dellamente.com Here you a

"Harland & Wolff were quite limited technically, with only their own
experience to draw on. They were aware of the power and economy the
turbine offered, although still unsure of its reliability, and chose
to play it safe ..."

Or is this another site that knows less than you about the Titanic?


It conflicts with what I've read about the design parameters laid out
for the Olympic class ships and discussion between Bruce Ismay (do you
even know who he is without Google?) and Lord Pirrie. I suggest you look
further. An excellent start would be to ask the question directly on the
Encyclopedia Titanica engineering forum.

I don't think you will, because I don't think you're interested in the
answer. You seem to be more interested in Jaxlike posturing and posing.
Certainly, a person with training in naval architecture would be able to
figure out prop slip, and would probably know where to find a good
reference to condensate depression.



Now THAT'S posturing!

Cheers

Nav wrote:

I don't think you will, because I don't think you're interested in the
answer. You seem to be more interested in Jaxlike posturing and
posing. Certainly, a person with training in naval architecture would
be able to figure out prop slip, and would probably know where to find
a good reference to condensate depression.


That is a bit unfair, Nav, prop slip is all over the board (+ or -)
depending on weather, load, currents and any number of things effecting
the hull ... even down to how good the helmsman is.

Rick

Rick, I didn't write that -Doug did.

Cheers

Rick wrote:
Nav wrote:

I don't think you will, because I don't think you're interested in
the answer. You seem to be more interested in Jaxlike posturing and
posing. Certainly, a person with training in naval architecture would
be able to figure out prop slip, and would probably know where to
find a good reference to condensate depression.



That is a bit unfair, Nav, prop slip is all over the board (+ or -)
depending on weather, load, currents and any number of things effecting
the hull ... even down to how good the helmsman is.

Rick

Nav wrote:


otnmbrd wrote:

Some comments interspersed

DSK wrote:

DSK the marine propulsion expert wrote:

In any case, the ship was going full speed, the loss of the prop
stream across the rudder would not reduce the rudder's
effectiveness very much.



This is probably most notable, in my experience, with variable pitch
props, but you can and will experience it with fixed pitch. You slow
the rpm of the prop and it tends to mess a bit with the smooth flow
of water past the rudder, reducing effectiveness until hull speed
reduces to rpm speed. (personal observation).


Yep, my point exactly. Wonder why he's never noticed it?

Cheers

Some things you notice on ships, you may not notice on boats, and vice
versa. Also, these effects can vary greatly in their intensity and it's
not a "given" that it will happen to a noticeable degree in all cases at
all times. BG One of the things which makes boat/ship handling so much
fun.

otn

DSK wrote:

That's about all folks. I'm getting pretty tired of Navvie's BS.

Nav wrote:

Ok you asked for it:

Nav:
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?


So, here you are quoting yourself making several wrong claims, with a
bwahaha and calling names besides.



DSK:
Actually, they are. The design (according to Harlan & Wolff, who
should know) called for inlet to the turbine at ~ 11 psia.


Know what this "~" means?


... 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... "


Yes, aren't you gald I told yiou that? But are you sure it's mmHg and
not inHg?


So you didn't get the hint, have no clue what Rick & I have been talking
about.

Now you pretend that you never claimed the exhaust and the condenser
aren't under vacuum, along with shirking all the other bogus statements
you've made.


No, I was the one who told you what the operating pressures were and
which you (of course) said was wrong. Your first post questioned whether
I knew how the turbine would be stopped (by closing a valve?). I told
you that the turbine would not be stopped by just closing a simple valve
(as that would also stop the main engines). So, this all started by my
saying a bypass valve would be opened, a point which you have finally
come to accept as _having_ to be true -despite your sneering and claims
to be an expert on the Titanic. In fact I've done nothing but post
factually correct statements and every one of them has been refuted and
attacked by you.

Perhaps you can explain why a self proclaimed marine propulsion engineer
with freshman thermodynamics and 20 years experience has never heard of
the term "steam dryness fraction" or recognise the equation for the
efficiency for a heat engine? I think I know why but I'd like to hear
your explanation.

If I "shirk" your questions it's because there are irrelevant to the
issue under discussion and anyway that's a very childish game (it's
called "I know something you don't").

Cheers

DSK wrote:


Actually, they aren't. There is no bypass from the HP and/or IP turbine
directly into the condenser in any plant I've ever steamed, naval or
civilian. So, there may be many plants out there with such valves, but
they're certainly not standard.


Well I guess this company for one never sells any?

http://www.emersonprocess.com/fisher...ditioning.html

Doug please try to engage your brain. In a plant where multiple engines
are used there has to be a way of taking one of them off line without
trashing steam flow in the whole plant right? Think about what happens
when a generating turbine trips! You can't just close the turbine inlet
valve as the boiler pressure would skyrocket. What you do is open a
bypass valve. In big plants you may also inject water to cool the steam
(it's pressure is dropped by adiabatic expansion after the valve) and
thence to the condenser.

If you have a plant where one engine takes the steam from another and
you want to drop the second off line you first open a bypass valve. So,
that's all, why did you even argue about it with me?


Cheers

DSK wrote:
Actually, they aren't. There is no bypass from the HP and/or IP
turbine directly into the condenser in any plant I've ever steamed,
naval or civilian. So, there may be many plants out there with such
valves, but they're certainly not standard.


Nav wrote:
Well I guess this company for one never sells any?

http://www.emersonprocess.com/fisher...ditioning.html

Thanks for one good laugh today. Did you read the description of these
valves? Did you just type "turbine bypass" into Google and grab the
first link that came up?



Doug please try to engage your brain. In a plant where multiple engines
are used there has to be a way of taking one of them off line without
trashing steam flow in the whole plant right?

Are you under the impression that a set of HP, IP, and LP turbines, all
geared to a common shaft, are considered "multiple engines"? What you're
talking about is a main steam loop.

A main steam loop has to supply power to propulsion engines (turbine or
whatever), feed pumps (recip or turbine), SSTG (do you what that stands
for?), and also feeds steam into auxiliary systems through pressure
reduction control valves & sometimes via desuperheaters. Some systems
have forced draft blowers on main steam also, but most FDBs are on an
aux loop.

A main steam loop is laid out similar to a firemain loop... the idea is
to supply all stations with redundant paths, so that you can isolate any
part of the system and still keep the rest running. Each section and
each piece of equipment will have stop valves and/or guarding valves.
Your "bypass valve" is for something else entirely.

... Think about what happens
when a generating turbine trips! You can't just close the turbine inlet
valve as the boiler pressure would skyrocket.

Why? Do you not have combustion controls down there? Or even firemen
that can stay awake on burner watch?


... What you do is open a
bypass valve.

That depends on the plant.

... In big plants you may also inject water to cool the steam
(it's pressure is dropped by adiabatic expansion after the valve) and
thence to the condenser.

That's not what is done on any marine plants I ever heard of, or for
that matter, any stationary ones. It would be incredibly wasteful of
fuel. Hey Rick, you following this?


If you have a plant where one engine takes the steam from another and
you want to drop the second off line you first open a bypass valve. So,
that's all, why did you even argue about it with me?

I'm not arguing, I was trying to explain some of the basics of what
likely happened when the watch officer on the bridge of the Titanic
tried to dodge that iceberg. Since this discussion has wandered so far,
I've mostly been laughing at you... trying to explain 'condensate
depression' with an integral, and confusing HP & LP turbines for
"multiple engines." Thanks for the laughs, Navvie.

DSK

That's not what is done on any marine plants I ever heard of, or for
that matter, any stationary ones. It would be incredibly wasteful of
fuel. Hey Rick, you following this?

No, have just got home a few minutes ago,brought a boat down from Alaska
and am now on my way to the airport to fly to Lauderdale for the
superyacht show ...

The only place water gets injected into the steam is in an attemperator
just before the evaporators. I cannot think of any single more wasteful
exercise than adding water to steam for any reason other than to cool
the steam going to an evaporator feed water heater running on live steam
rather than bleed steam.

Rick