Speed of a Nimitz-Class Carrier?
Krztalizer
Anyone know how fast a Nimitz can go at full speed on all four screws? Besides
Eisehower's cross-med high speed run, have any others been done with these
leviathans?
v/r
Gordon
<====(A+C====>
"How can you be so sure that it's an Echo II?" Nightdipper Pilot
"Because it just broached. Three o'clock...low." Nightdipper First Crewman
Steve Atkatz
On 17 Apr 1998 08:49:23 GMT, krzta...@aol.com (Krztalizer) fumbled
with the keyboard & wrote:
>Anyone know how fast a Nimitz can go at full speed on all four screws?
Not as fast as the SSN that's chasing it.
A to Z
***************************************
Age and Treachery will always prevail
Over Youth and Vigor. DBF!!!
Random
On Fri, 17 Apr 1998 12:52:39 GMT, ato...@idt.net (Steve Atkatz)
wrote:
>On 17 Apr 1998 08:49:23 GMT, krzta...@aol.com (Krztalizer) fumbled
>with the keyboard & wrote:
>
>>Anyone know how fast a Nimitz can go at full speed on all four screws?
>
>Not as fast as the SSN that's chasing it.
I don't know about that. What's the terminal speed of submarine that
made the mistake of going to full power in the vicinity of dipping
helos, even if all they had was Mk 46 torpedo? Takes the fish at 200
feet, pops the shaft seals, falls 5 miles to the bottom. Can it
really fall faster than 33 knots? <g>
Carriers as bait: an idea whose time has come. :)
random
Brian Varine
Steve Atkatz wrote:
>
> On 17 Apr 1998 08:49:23 GMT, krzta...@aol.com (Krztalizer) fumbled
> with the keyboard & wrote:
>
> >Anyone know how fast a Nimitz can go at full speed on all four screws?
>
> Not as fast as the SSN that's chasing it.
A CVN could whip the SSN chasing it. It's been stated many times that
the Nuke carriers were designed to outrun any torpedo in the world
(granted they were designed a while back but still). I think an SSN
would have a hard time chasing down most surface vessels in a race. Not
to mention a SSN full blast is going to be making a hellacious amount of
noise and be sunk. Torpedoing a CVN is much tougher than it seems.
Andrew Toppan
Krztalizer (krzta...@aol.com) was seen to write:
> Anyone know how fast a Nimitz can go at full speed on all four screws? Besides
Various reports indicate speeds of at least 40+ knots, and perhaps 50+.
Absurd reports indicate 70+ knots, but are obviously untrue. There's good
reason to believe 40+ is possible; theoretical hull speed is 44 knots,
IIRC.
> Eisehower's cross-med high speed run, have any others been done with these
> leviathans?
There are numerous reports of high-speed runs in various places.
--
Andrew Toppan --- el...@wpi.edu --- "I speak only for myself"
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Dave Welsh
Krztalizer wrote in message
<199804170849...@ladder03.news.aol.com>...
>Anyone know how fast a Nimitz can go at full speed on all four screws?
Besides
>leviathans?
>
I note that nobody has quoted a figure.
Based on the dimensions of the ship I would expect up to 40 knots.
Dave Welsh
dwe...@deltanet.com
Eugene Griessel
el...@WPI.EDU (Andrew Toppan) wrote:
>Krztalizer (krzta...@aol.com) was seen to write:
>> Anyone know how fast a Nimitz can go at full speed on all four screws? Besides
>Various reports indicate speeds of at least 40+ knots, and perhaps 50+.
>Absurd reports indicate 70+ knots, but are obviously untrue. There's good
>reason to believe 40+ is possible; theoretical hull speed is 44 knots,
>IIRC.
To lock horns with the Great Andrew.
I think these figures are patently absurd.
What is the speed of a ship? Most landlubbers and many salts seem to think a
ship has one true maximum speed. Yes, there is the measured mile which
attempts to measure such a speed. But speed is tied up with tonnage, the
"bend" of the hull, the surface of the hull and the air and sea temperatures
during the trial run. Even the salinity of the water has its effects.
Looking at the Nimitz class, I cannot calculate the power requirements because
I have no data other than that I get out of Janes - which does not allow me to
calculate, with any real accuracy, the wetted area and hence the total
resistance.
So I resort to the old Admiralty coefficient method.
When one sets out to design a ship, one of the first things needed is the
horsepower requirement so that a suitably large space can be designed into the
hull for the machinery. For this one uses one of a number of methods - but
the Admiralty Coefficient works well enough. Using the admiralty coefficient
and working backwards from the advertised horsepower, speed and tonnage of a
Nimitz class vessel I arrive at a figure around 300 - which is fairly
reasonable. It's what a vessel of that shape could be expected to have.
Using around 300 for AC and 93000 tons at a speed of 34 knots I find the
beast will need about 280 000 shp. To push it up to 40 knots I will need 547
379 shp and to get her to 50 knots will need 855 284 shaft horse power.
I doubt that she can put out that sort of power. If I calculate the other
way, taking her tonnage and speed and advertised power I start getting AC
figures that not even a torpedo manages to achieve.
Thus I must conclude that those who think a Nimitz will do 40 knots are sadly
deluded. 40 mph - yes at a giant squeeze with the chief sitting on the safety
valve. But not 40 knots. 50 knots its absolute fantasy. Beyond the
consideration of sane, reasonable and grizzled chief engineers.
Eugene L Griessel eug...@dynagen.co.za
www.dynagen.co.za/eugene
SAAF Crashboat Page - www.dynagen.co.za/eugene/eug3.htm
Thought for the day .......
Leadership: the art of getting someone else to do something you want
done because he wants to do it.
Dave Anderer
On 17 Apr 1998 15:06:15 GMT, el...@WPI.EDU (Andrew Toppan) wrote:
>Krztalizer (krzta...@aol.com) was seen to write:
>> Anyone know how fast a Nimitz can go at full speed on all four screws? Besides
>
>Various reports indicate speeds of at least 40+ knots, and perhaps 50+.
"Reports", or "sea stories"? If they're considered legitimate
reports, do you have a cite or two?
I have no direct knowledge of the correct answer, but I think two
things need to be kept in mind:
1. Conditions under which the measure was made. Most people assume
there's only one right answer here, but the number reached
very-light-and-just-out-of-drydock may be significantly different than
the been-in-the-IO-for-100+-days number.
2. Throughout history, folks have played "how fast is she". Every
time this game is played, the numbers seem to inflate from reality.
Some folks/governments have a vested interest in this inflation; other
times it just seems to happen spontaneously for a "better story."
The only numbers I'm really comfortable with are the trial numbers,
which generally include speed, SHP, displacement, time since docking,
and water depth (or the specific course run.) That data gives the
necessary context for judging speed.
Now, can anyone cite a case where a ship, under controlled conditions
like this, exceeded their "reputation" speed? Stunts - like running
with minimum fuel, no potable water, no stores, etc - don't count.
So, I'm skeptical of many of the high numbers offered in this group.
D.C.KOH
Eugene Griessel wrote:
>
<interesting post about CVN hull coefficients snipped>
> Thus I must conclude that those who think a Nimitz will do 40 knots are sadly
> deluded. 40 mph - yes at a giant squeeze with the chief sitting on the safety
> valve. But not 40 knots. 50 knots its absolute fantasy. Beyond the
> consideration of sane, reasonable and grizzled chief engineers.
>
launch aircraft (obviously) at the lower figure and make life hard for
pursuing subs (who hate to run for obvious reasons). In any case, the
higher figure still doesn't allow the CVN to outrun enemy aircraft.
Dan
Thomas A. Beckley
>>> Anyone know how fast a Nimitz can go at full speed on all four screws?
Besides
>
>>Various reports indicate speeds of at least 40+ knots, and perhaps 50+.
sadly
>deluded. 40 mph - yes at a giant squeeze with the chief sitting on the
safety
>valve. But not 40 knots. 50 knots its absolute fantasy. Beyond the
>consideration of sane, reasonable and grizzled chief engineers.
>
The true maximum output of the plant of all nuclear ships is *CLASSIFIED*.
It is commonly known that nuclear plants can go to maximum power ratings
that would not be used except under emergency circumstances, such as when
trying to outrun a torpedo. I doubt that the true maximum speed capability
has truly been tested of the modern nuclear carriers, because there has been
no situation where a nuclear carrier's safety was in imminent danger and it
needed to flee.
Andrew Venor
As a former chief machinery operator in the Abraham Lincoln's number 2
main machinery room, I can say it is very fast. As for the actual number,
that a secret.
ALV
Krztalizer wrote:
> Anyone know how fast a Nimitz can go at full speed on all four screws? Besides
> Eisehower's cross-med high speed run, have any others been done with these
> leviathans?
>
Guy Derdall
Her reactors much like the older steam plants usually have an overload in
them
I know the Iowa's was 254,000 shp on overload.
This is probably how the Nimitz's can go 40+ knots. Many people have said
they can, but who knows right?
My bet is on the 40+ speeds. 50+ being a little excess.
--
*****************************************************
Guy Derdall
Battleships Carriers And All Other Warships
http://warships.4biz.net/index2.htm
"The Anchor Page For The World's Warships"
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e-mail battl...@sk.sympatico.ca
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Eugene Griessel wrote in message <35378...@hawk.pix.za>...
>el...@WPI.EDU (Andrew Toppan) wrote:
>
>>Krztalizer (krzta...@aol.com) was seen to write:
>>> Anyone know how fast a Nimitz can go at full speed on all four screws?
Besides
>
Dave Anderer
On 17 Apr 1998 15:06:15 GMT, el...@WPI.EDU (Andrew Toppan) wrote:
>Various reports indicate speeds of at least 40+ knots, and perhaps 50+.
>Absurd reports indicate 70+ knots, but are obviously untrue. There's good
>reason to believe 40+ is possible; theoretical hull speed is 44 knots,
>IIRC.
LWL for CVN 68 is 1040', so 1.3 * sqrt (1040) is about 42 knots. So I
agree we're talking low 40's. However..
Let's take some other data points. LWL of CVA59 was 990'. That
implies a maximum speed of 41 knots. I've never heard any claim the
conventional carriers were/are that fast. Yet based on hull length
alone, you might expect them to be. Trial speed for CVA59 is reported
as just under 33 knots.
Likewise, a Midway should have been good for 39 knots. Trial speed
was also 33 knots.
Clearly, it's more complicated than just length. As a first cut, I
assume that the ships don't have either 1. the power necessary to
reach hull speed, or 2. the ability to transfer the needed power to
the water. Effectively, that's the same thing.
So let's look at power. From what I've read, the USN figures on power
tend to be fairly accurate. While they equivocate on speed,
non-nuclear power numbers seem to represent reality. So let's make
that assumption. We know that:
Midway made 33 knots displacing 58K tons, producing 215K HP.
Forrestal made 33 knots, displacing 76K tons, producing 251K HP.
This strongly suggests to me, that IF the HP numbers for nuclear
carriers are anywhere near correct (280K or a bit more), there is no
way 50 or even 40 knots makes sense. In fact, 33 knots would seem to
be about the right number.
As another data point, BuShips did a series of conventional carrier
designs in 1953. The largest - fairly close to a Nimitz - was
estimated to require 295K HP to make 33 knots.
The inference here is that for a nuke to make even 40 knots, they have
a lot more power than is publicly admitted. A LOT more. Which means
bigger drive trains, more efficient props, etc. Possible? Yup.
Likely? I don't think so.
It just doesn't make sense. Much of the trial data we know supports
Friedman's contention that the design point for US carriers was a 30
knot SUSTAINED speed. Why, when every design is a compromise between
capability and funding, would so much be spent for additional speed?
What good is the speed without escorts that can keep up?
I don't know the "right" answer here. Personally, I'd buy maybe 37-38
knots, loaded, with a clean bottom. Very possibly less.
Dave Anderer
>So I resort to the old Admiralty coefficient method.
Could you talk a little about this method? I'm not familiar with it,
but it sounds interesting. It must be accurate, because it supports
"my" conclusions. :)
Andrew Toppan
Eugene Griessel (eug...@dynagen.co.za) was seen to write:
> I doubt that she can put out that sort of power. If I calculate the other
I wouldn't doubt those figures. It's hard to imagine that shp in CV/CVN
designs has not gone up AT ALL in the 40+ years since FORRESTAL was
designed. FORRESTALs were at 260,000-280,000 hp; it's rather hard to
believe they couldn't manage to squeeze just a bit more out of a much more
modern nuclear plant.
Further, your contention that 30 is a true top speed contradicts numerous
reports by "pepole who were there" of CVs doing considerably higher
speeds. Were they all liars?
And it's reliably known that the FORRESTALs could do just over 30 on
280,000 hp. If the NIMITZs were running at that HP rating, I'm quite sure
they couldn't even make 30 knots - a patently absurd idea.
Andrew Toppan
Dave Anderer (dand...@udel.edu) was seen to write:
> "Reports", or "sea stories"? If they're considered legitimate
> reports, do you have a cite or two?
Reports, typically in the form of
"I was on the bridge of the cruiser USS XXX and we were doing 30 knots
when the carrier XXX blew by us doing at least 10 knots better than us"
"I was on the bridge of the carrier USS XXX and saw the knotmeter showing
XX knots"
etc, etc, etc. They've all been posted here before...
> The only numbers I'm really comfortable with are the trial numbers,
Which, conventiently for you, are not available...
> So, I'm skeptical of many of the high numbers offered in this group.
So you're calling *all* of these people liars? Perhaps some have inflated
their claims...but did everyone?
Andrew Toppan
> implies a maximum speed of 41 knots. I've never heard any claim the
> conventional carriers were/are that fast. Yet based on hull length
Horsepower limitations of the conventional plant. Nuke plants can put out
a lot more HP.
> tend to be fairly accurate. While they equivocate on speed,
> non-nuclear power numbers seem to represent reality. So let's make
There's the key - *non nuclear* numbers. You've got no nuclear numbers,
and the assumption that nuke and non-nuke numbers are the same is probably
not valid.
Eugene Griessel
"D.C.KOH" <RA6...@QMWCC7.qmw.ac.uk> wrote:
>Does it really matter if it's 30+ knots and not 50+ knots? You can still
>launch aircraft (obviously) at the lower figure and make life hard for
>pursuing subs (who hate to run for obvious reasons). In any case, the
>higher figure still doesn't allow the CVN to outrun enemy aircraft.
As we always reasoned - no matter how fast the tub will go, there is a missile
that will go faster.
But I do get pissed off with people who claim incredible speeds for ships - I
spent a lot of my seagoing time on fast vessels and I know the awesome amounts
of power needed. The Iranian Saam and Zaal were impressive at 40 knots. But
it took an awesome 46000 shp to boil up to that speed. And they displaced
only 1300 tons. And as every chief, myself included, will tell you - they
don't like doing that sort of thing routinely. It does nasty things to the
machinery.
Eugene L Griessel eug...@dynagen.co.za
www.dynagen.co.za/eugene
SAAF Crashboat Page - www.dynagen.co.za/eugene/eug3.htm
Thought for the day .......
I have a great faith in fools; self-confidence my friends call it.
Eugene Griessel
dand...@udel.edu (Dave Anderer) wrote:
The actualy formula is simple. It is represented by the tonnage raised to the
power 0.6666666 multiplied by the speed (in knots) cubed and then the shebang
is divided by the AC to give shaft horsepower. The AC depends on a lot of
things and is usually taken from a graph of lengths. The AC runs from about
270 for the slimmest of destroyers through to about 600 for a wallowing tub of
a merchantman. There is a preliminary design formula to calculate a more
accurate AC but for this model data is needed. Which, for the Nimitz, I do
not have.
Eugene Griessel
el...@WPI.EDU (Andrew Toppan) wrote:
>I wouldn't doubt those figures. It's hard to imagine that shp in CV/CVN
>designs has not gone up AT ALL in the 40+ years since FORRESTAL was
>designed. FORRESTALs were at 260,000-280,000 hp; it's rather hard to
>believe they couldn't manage to squeeze just a bit more out of a much more
>modern nuclear plant.
Firstly the turbine for a nuclear ship is of necessity physically a much
larger device than that running on superheated steam. Rule of thumb in the
nuclear industry says 3 times larger. Although that was in 1980 - but Nimitz
was at sea already. Secondly the reactor is larger and heavier than a boiler
of similar power output. I am talking total size including shielding, heat
exchangers and pressurisers. Whatever you do you cannot change the amount of
power needed to push a given hull at a certain speed. Whether that push is
from nuclear or gas turbine or conventional steam. I have never, in 20 years,
seen a figure other than 260 000 to 280 000 quoted for these vessels.
(Although some of the later ones may be higher - I have not kept that good a
track).
>Further, your contention that 30 is a true top speed contradicts numerous
>reports by "pepole who were there" of CVs doing considerably higher
>speeds. Were they all liars?
Where pray tell did I quote 30 as a true top speed? Please show me? I can
recall using 34 knots in my calculation. That is the speed most reference
works give. And it is a reasonable speed for that power and hull.
How did the "people who were there" figure out the speed? How does anyone
tell the speed of a ship? Measured mile is the only truly accurate figure.
Don't quote the log at me - those thing have large errors when it comes to
instaneous readings. Logs are only useful for speed measurement over a
distance. And I have shared ships with excited seamen who have claimed speeds
that I know we were incapable of if I had the entire engine room staff eating
beans and facing backwards. Yes - I will call anyone who tells me Nimitz
could do a true 40 knots a liar. And I have a very good reason for that.
>And it's reliably known that the FORRESTALs could do just over 30 on
>280,000 hp. If the NIMITZs were running at that HP rating, I'm quite sure
>they couldn't even make 30 knots - a patently absurd idea.
I'm not sure I follow your reasoning here Andrew. The Forrestal class have
always had a published top speed of 34 knots except for Forrestal herself
which was 33 knots. I imagine these were obtained in standard conditions over
the measured mile. Forrestal had different machinery to her sisters and was
20 000 hp less than the rest of her class. The Kitty Hawk class also had a
published figure of 280000 shp and a speed of 33 knots. The Enterprise had
much the same figures.
And so do the Nimitz class.
So point me to any sources that differ on shp for the Nimitz class.
Jeff Crowell
Dave Anderer wrote:
: LWL for CVN 68 is 1040', so 1.3 * sqrt (1040) is about 42 knots. So I
: agree we're talking low 40's. However..
Yet this is just an approximation. I personally was aboard a ship doing a
max power run which exceeded its 'hull speed' by 3+ knots, this while in
'normal' conditions, i.e. dirty hull (just back from a WestPac, and she'd
never been drydocked and scraped), we'd refuelled that day, normal potable
water levels (i.e. full), etc.
3+ knots is, IMO, a signficant delta. Say, greater than 10%...
For this type of ship, the limitation was how much power could be jammed
through the prop shafts without twisting 'em off like breadsticks, at
least for sprints. The long-term limitation was that we were burning
Navy Distillate faster than my guys (Fuels Div.) could transfer and
purify it, though I suspect if things were Really Important (tm) we
woulda put online FOS tanks that hadn't been recirced the requisite
number of hours.
Fast as we were, we got left behind a couple of times.
Jeff
--
Jeff Crowell | |
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O x x O
The two most common elements in the universe are hydrogen and stupidity.
William J Bollinger
eug...@dynagen.co.za (Eugene Griessel) wrote:
<snip>
>How did the "people who were there" figure out the speed? How does anyone
>tell the speed of a ship? Measured mile is the only truly accurate figure.
>Don't quote the log at me - those thing have large errors when it comes to
>instaneous readings. Logs are only useful for speed measurement over a
>distance.
A Mk3 Mod7 SINS in my day. That's a gyro-stabilized platform with
accelerometers. When kept properly aligned, it was pretty accurate. We
kept ours properly aligned. It said 40+ knots.
Support the American Academy of Industry in their effort to save the aircraft carrier Cabot and the cruiser Des Moines.
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Eugene Griessel
bda...@twr.org (Bill Damick) wrote:
>Short run top speed aside - the really great thing about being afloat
>on a nuke ship was that it could maintain flank speed a whole lot
>longer than an oil-burner. I was on the USS California back in 1981,
>and we made a transit from Rota around Africa the long way up to GONZO
>station at an average speed of somewhere around 28kts - all by our
>lonesome. Took around 3 weeks more or less. Would love to see you
>try that on a tanker-teathered CG, CA, or CV! The down side was that
>is was pretty miserable down in the engine hole. The up side was a
>nice breezy passage during shellback ceremonies.
And there you have the great advantage of a nuke - high speed is constantly on
line at no extra cost. A nuke can transit between two distant ports at a much
higher average speed than your oil-burner. This advantage is infinitely more
precious than dash speed that can be maintained for a few hours before the
tanker is needed. One of the reasons I am so surprised at the US decision to
scrap the nuclear cruisers. With them a CV task force did not have to steam
at the speed of the fleet train. Now you have carriers that can go dashing
about - but are in reality hampered by the fact that the escorts need constant
fuel and that comes in slow fleet tankers.
Eugene L Griessel eug...@dynagen.co.za
www.dynagen.co.za/eugene
SAAF Crashboat Page - www.dynagen.co.za/eugene/eug3.htm
Thought for the day .......
Civilization is a race between education and catastrophe.
Andrew Toppan
> seen a figure other than 260 000 to 280 000 quoted for these vessels.
SO WHAT? The US Navy has said, time and time again, that horsepower and
speed figures for nuclear ships are not released. The 280,000/30+ is
admittedly not the true hp/speed. The fact that you've seen it a lot is
NOT proof that these figures are correct.
> Where pray tell did I quote 30 as a true top speed? Please show me? I can
> recall using 34 knots in my calculation. That is the speed most reference
OK, you said 34. The difference from 30 is not particularly large nor
relevant. 4 knots is a good margin for hull fouling, load differences,
etc. anyway.
> How did the "people who were there" figure out the speed? How does anyone
> tell the speed of a ship? Measured mile is the only truly accurate figure.
> Don't quote the log at me - those thing have large errors when it comes to
> instaneous readings. Logs are only useful for speed measurement over a
So you're telling me that no log is ever accurate? Then why bother having
them?
> I'm not sure I follow your reasoning here Andrew. The Forrestal class have
> always had a published top speed of 34 knots except for Forrestal herself
> which was 33 knots. I imagine these were obtained in standard conditions over
> the measured mile. Forrestal had different machinery to her sisters and was
What I'm saying is that it's almost unbelievable that in 40+ years of
carrier design we haven't manged to squeeze a single extra horepower out
of the plants. The ships are longer, the displacement is much higher, but
nobody along the way thought to upgrade the propulsion? Ridiculous.
Hell, Friedman claims the NIMITZ class went DOWN in shp from 280,000 to
260,000. Tell me another funny story...
> So point me to any sources that differ on shp for the Nimitz class.
The whole point is that the published figures for the class are
INTENTIONALLY MISLEADING. Your entire argument is based on those figures,
and is therefore bogus.
SeaPhoto
>And there you have the great advantage of a nuke - high speed is constantly
As someone with a passable knowledge of machinery, I think it pretty likely
that running any plant at maximum output for extended periods of time would be
pretty tough on the various components.
Are the turbines, shafts, bearings and such beefed up in nuclear ships? If so,
does the increase in weight offset the power to any extent?
Kurt Greiner
SeaPhoto Maritime Photography
Still the same old website:
http://members.aol.com/SeaPhoto/index.html
Dale Hillier
Nice Post, I'll take this one on as well.....
dand...@udel.edu (Dave Anderer) writes:
>The inference here is that for a nuke to make even 40 knots, they have
>a lot more power than is publicly admitted. A LOT more. Which means
>bigger drive trains, more efficient props, etc. Possible? Yup.
>Likely? I don't think so.
The highest speed that I have ever head of CVN go is 67 kts, IIRC it was
Carl Vinson in the IO some years back. I think that we can safely assume
that 67 kts is rather absurd. However I do agree with Dave's point that
the power output of CVNs is grossly underrated for the vessel to make
turns in excess of 35 kts.
However, we are talking about nuclear power here.....I will propose that
the SHP of most nuclear vessels is rather higher than in published
documents. If this IS the case, then I would speculate a speed 45 kts,
maybe a little more. There is no logrithmic (SP?) increase in HP for the
corresponding increase in speed. A large increase in HP is needed for
even a 1 kt increase in speed. I am not an engineer, just a driver so I
may have this screwed up a little.
Then there is the material engineering aspect of this to contimplate.
CVNs are simply large steam plants that use the reactor to boil water.
This is an over simplistic view but we aren't talking about the plumbing
system. The steam is used to drive the turbines that make the ship move.
In order to move the turbines, the steam has to be under pressure,
pressure that is created by the superheated steam.
Steam piping has a maximum limit as to what kind of pressure it can bear.
This is solved by having larger, thicker piping but that results in
increased costs and I don't think that the US Congress is willing to shell
out X many billions for a vessel that already costs 2 or 3 billion
already.
In short, CVN speed is limited by hull form, size (HP vs. speed), and the
max load of the various engineering systems.
I'd say not much past 45 kts. BUT.....
Later
D
--
>Dale Hillier |"Time is the only excuse that keeps<
>Professional Merchant Mariner |everything from happening at once."<
>I note the Difference | <
>http://www.ucs.mun.ca/~hillier/index.htm |Phillip Hiller, Rigel Shipping <
Eugene Griessel
el...@WPI.EDU (Andrew Toppan) wrote:
Some calculations on the Nimitz.
I am using the following:
Hull length: 1080 feet (330 metres)
Displacement: 90 000 tons
These are rough figures as I have none for waterline length.
Using Taylor's formula to calculate wetted area - and guessing at a C of
around 2.58 for fast ships - then I get 90000 x 330 = 29700000 of which the
square root is 5449.8. Multiplied by 2.58 gives me 14060 square
metres. (God I hate doing math on a word processor). Wetted area is thus
approx. 14 060 square metres.
This gives me a frictional resistance component of:
14060 x 20.6 (speed in metres per second at 40 knots) x 1.382 (frictional
constant for 330 metres) = 400276.95 and this gets raised to the power 1.825
giving me 16761310000 newtons frictional resistance - or 16761310 kN. So to
overcome the frictional component alone we need this amount of power at 40
knots.
I have air resistance - in this case I can say about 3% of the total will be
air resistance.
Eddy making resistance is minimal but the wave making resistance
is not. I unfortunately have no graphs for a ship this size at that speed.
Also this is highly dependent on hull form, beam and length.
To get the power needed the formula is:
P = Resistance total x speed in knots x 0.5144 (knots to metres per second) If
you plug in the figures you will find that this ship needs about 460 000 shp
merely to overcome the frictional resistance at 40 knots.
This is a physical fact. My data may be out a bit but I will stake my claim
on a minimum of 400 000 shp to overcome frictional resistance. Bung in
air resistance - another 12000 horses. Now eddy and wave-making resistance
need to be added. At this I can only make an educated guess.
However we are going to end up with a minimum close to 500 000 shp.
Now to increase a ship's given power from the commonly accepted 280 000 shp
that standard reference works have claimed for more than 20 years to
around 500 000 shp is a major increase in size and weight of the machinery.
I have never seen this sort of powering even hinted at in any respectable
reference.
Feel free to point me at a work that claims differently.
Feel free to put me in contact with a naval architect who says different.
Hell Andrew - just figure the power this lump of steel would need to
get it moving at 40 knots if it were a car. Should be simple enough.
Its always easy to hide behind the "its more but I cannot tell you argument".
By the time this ship approaches the sorts of speeds being claimed it is going
to be all engineroom and nothing else.
The simple facts are that 40 knots is a sea story. I challenge you to prove
differently.
Eugene L Griessel eug...@dynagen.co.za
www.dynagen.co.za/eugene
SAAF Crashboat Page - www.dynagen.co.za/eugene/eug3.htm
Thought for the day .......
One can always tell a well-informed man.
His views are the same as yours.
Eugene Griessel
seap...@aol.com (SeaPhoto) wrote:
>>And there you have the great advantage of a nuke - high speed is constantly
>line at no extra cost.<
>As someone with a passable knowledge of machinery, I think it pretty likely
>that running any plant at maximum output for extended periods of time would be
>pretty tough on the various components.
>Are the turbines, shafts, bearings and such beefed up in nuclear ships? If so,
>does the increase in weight offset the power to any extent?
No - running at high speed is not necessarily running at top speed. And if
you know a ship will constantly steam at 30 knots then you can design for
that. No ship can do balls-to-the-wall speeds constantly without suffering
damage. In Germany they used to talk of a powerplant having a "maximum"
rating, and "emergency" rating and a "high emergency" rating. The maximum is
what you could expect constantly. The other two you paid for in varying
degrees of life in the machinery.
Krztalizer
>
>Further, your contention that 30 is a true top speed contradicts numerous
>reports by "pepole who were there" of CVs doing considerably higher
>speeds. Were they all liars?
>
>280,000 hp. If the NIMITZs were running at that HP rating, I'm quite sure
>they couldn't even make 30 knots - a patently absurd idea.
>
>Andrew Toppan
My secondary question is this -- how fast would this 1,009-foot ship have to
be traveling in order to get the entire bow of the ship out of the water? The
Destroyer USS Hull took a photo of us during a VERY hight speed run, and we
were out of the water almost back to the island. Almost, but not quite.
Anyone who thinks we were moving at less that 35 knots that night is mistaken
-- to say that the Nimitz class is not capable of greater speeds than that has
never felt all 89,000 tons rattle and roll under accelleration.
Eugene Griessel
hil...@morgan.ucs.mun.ca (Dale Hillier) wrote:
>The highest speed that I have ever head of CVN go is 67 kts, IIRC it was
>Carl Vinson in the IO some years back. I think that we can safely assume
>that 67 kts is rather absurd. However I do agree with Dave's point that
>the power output of CVNs is grossly underrated for the vessel to make
>turns in excess of 35 kts.
Hell - why not just put wings on the thing and get it airborne at the speeds
you are claiming.
>However, we are talking about nuclear power here.....I will propose that
>the SHP of most nuclear vessels is rather higher than in published
>documents. If this IS the case, then I would speculate a speed 45 kts,
>maybe a little more. There is no logrithmic (SP?) increase in HP for the
>corresponding increase in speed. A large increase in HP is needed for
>even a 1 kt increase in speed. I am not an engineer, just a driver so I
>may have this screwed up a little.
Go down into the stokehold and root out your chief. (That's the fellow
constantly covered in oil and grease who curses even more than a standard
sailor). Run the figure of 45 knots by him. Scrape him off the deck when
his paroxysms of laughter have finally come to a halt.
>Then there is the material engineering aspect of this to contimplate.
>CVNs are simply large steam plants that use the reactor to boil water.
>This is an over simplistic view but we aren't talking about the plumbing
>system. The steam is used to drive the turbines that make the ship move.
>In order to move the turbines, the steam has to be under pressure,
>pressure that is created by the superheated steam.
No superheated steam, only wet steam from a nuke.
>Steam piping has a maximum limit as to what kind of pressure it can bear.
>This is solved by having larger, thicker piping but that results in
>increased costs and I don't think that the US Congress is willing to shell
>out X many billions for a vessel that already costs 2 or 3 billion
>already.
>In short, CVN speed is limited by hull form, size (HP vs. speed), and the
>max load of the various engineering systems.
>I'd say not much past 45 kts. BUT.....
It would not do 45 knots if you put 50 billion volts through it!
Eugene L Griessel eug...@dynagen.co.za
www.dynagen.co.za/eugene
SAAF Crashboat Page - www.dynagen.co.za/eugene/eug3.htm
Thought for the day .......
They never let you live it down. One little mistake! - Nero
Dave Anderer
On 17 Apr 1998 18:29:37 GMT, el...@WPI.EDU (Andrew Toppan) wrote:
>Eugene Griessel (eug...@dynagen.co.za) was seen to write:
>> I doubt that she can put out that sort of power. If I calculate the other
>
>I wouldn't doubt those figures. It's hard to imagine that shp in CV/CVN
>designs has not gone up AT ALL in the 40+ years since FORRESTAL was
>designed. FORRESTALs were at 260,000-280,000 hp; it's rather hard to
>believe they couldn't manage to squeeze just a bit more out of a much more
>modern nuclear plant.
>
Two points:
1. Let's not gloss over the magnitude of the numbers - we're talking
between a 50% and a 100% increase in power required to reach these
speeds. That's power transmitted to the water - requiring not only
"nuclear magic" for the higher HP, but major investments in the
turbines, shafting, props, etc. HP without the drive train don't mean
much - witness the latest Ticos (?), which are drive train limited.
2. Even if it was technically possible to achieve this increase, I'm
not convinced the decision to do it would be made. Some examples:
Atlanta (1940s) 7,400 tons 80,000 HP
Spruance (1970s) 7,800 tons 80,000 HP
Gearing (1940s) 2,800 tons 60,000 HP
OHP (1970s) 3,500 tons 40,000 HP
Why, over 30 years of naval progress, don't we see substantial HP
increases in similar-sized ships? Not because it was technically
impossible, but rather because there were decisions made that the
additional HP was not the proper compromise. Like it or not, even
with technology, performance COSTS. All of the available, reliable
data - up to the 1960s - suggests the USN has never thought that high
speed - more than about 32-33 knots sustained - was worth the
trade-off in other areas.
Danimitzman
On Feb 26, 1998, the USS John C. Stennis departed Norfolk, and got to the
Gulf in either 13 or 15 days- I think 15 would be more reasonable. So, you
could go and do a lotta research and find out how fast they were going. The
official report said average speed was "28 knots" But last year, when Iraq
was acting up again, the USS George Washington took 10 days to go from the
Med to the Gulf via the Suez, and they said the GW was traveling at flank
speed. So, the USS John C. Stennis must have been going more than 28!!!
Dman
Krztalizer wrote in message
<199804170849...@ladder03.news.aol.com>...
>Anyone know how fast a Nimitz can go at full speed on all four screws?
Besides
>Eisehower's cross-med high speed run, have any others been done with these
>leviathans?
>
75270...@compuserve.com
In message <6h872h$o0a$1...@bigboote.WPI.EDU> - el...@WPI.EDU (Andrew Toppan)
writes:
|
|Eugene Griessel (eug...@dynagen.co.za) was seen to write:
|> I doubt that she can put out that sort of power. If I calculate the other
|
|I wouldn't doubt those figures. It's hard to imagine that shp in CV/CVN
|designs has not gone up AT ALL in the 40+ years since FORRESTAL was
|designed. FORRESTALs were at 260,000-280,000 hp; it's rather hard to
|believe they couldn't manage to squeeze just a bit more out of a much more
|modern nuclear plant.
|
|reports by "pepole who were there" of CVs doing considerably higher
|speeds. Were they all liars?
|
|And it's reliably known that the FORRESTALs could do just over 30 on
|280,000 hp. If the NIMITZs were running at that HP rating, I'm quite sure
|they couldn't even make 30 knots - a patently absurd idea.
|
|--
I don't know anything about screw design, but I think you have to
consider the possibility that screws are designed for maximum efficiency
at 25 - 30 kts. Their efficiency may drop off at higher speed so that
the additional available hp is tough to use.
scott s.
.
75270...@compuserve.com
In message <6h87p7$o0a$3...@bigboote.WPI.EDU> - el...@WPI.EDU (Andrew Toppan)
writes:
|
|Dave Anderer (dand...@udel.edu) was seen to write:
|> Let's take some other data points. LWL of CVA59 was 990'. That
|> implies a maximum speed of 41 knots. I've never heard any claim the
|> conventional carriers were/are that fast. Yet based on hull length
|
|Horsepower limitations of the conventional plant. Nuke plants can put out
|a lot more HP.
|
|> tend to be fairly accurate. While they equivocate on speed,
|> non-nuclear power numbers seem to represent reality. So let's make
|
|There's the key - *non nuclear* numbers. You've got no nuclear numbers,
|and the assumption that nuke and non-nuke numbers are the same is probably
|not valid.
|
|Andrew Toppan --- el...@wpi.edu --- "I speak only for myself"
Nuke or non-nuke, the turbine output and screw efficiency are what matters.
My conventional experience is that ability to maintain condensor
vacuum on the ME was the limiting factor -- the boilers were not maxed.
(And of course I still had the "overload" plates locked up in my
stateroom). So my belief is you need to look at the turbines and
screws to get your answer.
scott s.
.
Patrick Pemberton
Eugene Griessel said:
> How did the "people who were there" figure out the speed? How does anyone
> tell the speed of a ship? Measured mile is the only truly accurate figure.
GPS, excellent visual and radar fixes, maneuvering board by another ship
who knows her course and speed, etc.
-Patrick
Visit the USS Texas Photo Archive at:
<A href="http://www.ece.utexas.edu/~pemberto/texas">
http://www.ece.utexas.edu/~pemberto/texas
</a>
Dave Anderer
On 17 Apr 1998 20:35:26 GMT, el...@WPI.EDU (Andrew Toppan) wrote:
>The whole point is that the published figures for the class are
>INTENTIONALLY MISLEADING. Your entire argument is based on those figures,
>and is therefore bogus.
Well, of course the figures are superficially misleading. Navies have
played this game forever. But think some:
Historically, have navies encouraged reputations for their ships which
OVERSTATE or UNDERSTATE their speed? Including the USN - witness the
Atlantas and Iowas. The answer is: The speeds get overstated -
either by the navy directly, or at least any misconceptions are not
aggressively corrected. But you're suggesting that, in this case, the
USN is successfully doing just the opposite? From a
historical/organizational perspective, that's just not likely.
Again, historically, the USN has been pretty accurate with their HP
numbers. I think we all freely admit that 280K HP doesn't equal 40
knots. But again, you're suggesting the USN has gone completely
against form here? Ditto my previous comment.
Dave Anderer
On 17 Apr 1998 18:39:31 GMT, el...@WPI.EDU (Andrew Toppan) wrote:
>Reports, typically in the form of
> "I was on the bridge of the cruiser USS XXX and we were doing 30 knots
>when the carrier XXX blew by us doing at least 10 knots better than us"
>
>"I was on the bridge of the carrier USS XXX and saw the knotmeter showing
>XX knots"
>
>etc, etc, etc. They've all been posted here before...
Ok, those are data points. I don't dismiss them, but I also don't
accept them completely, 100%, at face value. There can be problems
with eyewitness testimony - be they about plane crashes or vehicle
speeds.
>
>> The only numbers I'm really comfortable with are the trial numbers,
>
>Which, conventiently for you, are not available...
Wasn't it nice how I arranged that? Boy, I've had trouble having the
USN keep them secret...
>
>> So, I'm skeptical of many of the high numbers offered in this group.
>
>So you're calling *all* of these people liars? Perhaps some have inflated
>their claims...but did everyone?
Calm down. I've called no one a liar. What I've said is that I
believe the engineering data and the USN's historical choices in ship
design make it unlikely the high speeds quoted are correct.
Physics is physics.
Dave Anderer
On 17 Apr 1998 18:41:43 GMT, el...@WPI.EDU (Andrew Toppan) wrote:
>Horsepower limitations of the conventional plant. Nuke plants can put out
>a lot more HP.
Oh, pooh. Put up or shut up. Document for me that Nimitz plant can
put 400K HP INTO THE WATER.
>There's the key - *non nuclear* numbers. You've got no nuclear numbers,
>and the assumption that nuke and non-nuke numbers are the same is probably
>not valid.
Lacking any evidence to the contrary, I see it as a reasonable
assumption. You have evidence? Again..
Let's review:
Pro-40-knots-plus:
"The published figures are wrong - nuclear plants put out LOTS
and LOTS of hp."
"People say they go this fast.."
Anti-40-knots-plus:
"Physics - both in theory and comparing the performance of
similar-sized-ships - tells us that 40 knots requires LOTS of HP."
"The USN HP figures have traditionally been fairly accurate."
"If the published HP figures are even understated by 30%, they
can't go that fast."
"Even in the nuclear world, speed costs - either money, or
capability tradeoffs."
"The USN has never sought very high speed at the expense of
other qualities."
"None of the supporting ships - DDs, CGs, SSNs - have this
high a speed. Why build them slow if the carrier is fast?"
One final point - I don't think sprint speed was EVER raised during
the CVA 67 battle. If nuke carriers had warp engines, don't you think
it would have been?
Joshua Turner
snip
>
> Go down into the stokehold and root out your chief. (That's the fellow
> constantly covered in oil and grease who curses even more than a standard
> sailor). Run the figure of 45 knots by him. Scrape him off the deck when
> his paroxysms of laughter have finally come to a halt.
>
> >Then there is the material engineering aspect of this to contimplate.
> >CVNs are simply large steam plants that use the reactor to boil water.
> >This is an over simplistic view but we aren't talking about the plumbing
> >system. The steam is used to drive the turbines that make the ship move.
> >In order to move the turbines, the steam has to be under pressure,
> >pressure that is created by the superheated steam.
>
> No superheated steam, only wet steam from a nuke.
>
> >Steam piping has a maximum limit as to what kind of pressure it can bear.
> >This is solved by having larger, thicker piping but that results in
> >increased costs and I don't think that the US Congress is willing to shell
> >out X many billions for a vessel that already costs 2 or 3 billion
> >already.
>
> >In short, CVN speed is limited by hull form, size (HP vs. speed), and the
> >max load of the various engineering systems.
>
> >I'd say not much past 45 kts. BUT.....
>
> It would not do 45 knots if you put 50 billion volts through it!
>
Just curious, where does the SS United States fit in to this debate?
Obviously, the US has a much different hull form from the carriers, is
just under 1000 ft, and weighs substantially less than the carriers (her
GRT was 53,000--I can't find a source on her displacement, but it was
certainly far short of 90K tons). But with 240,000 hp, the US could
cruise comfortably at 36 knots (average speed on her maiden voyage was
35.53), and her actual top end was quite a bit higher than that--reports
differ, but it's been said that she hit 43 kts during sea trails. Even
if 43 is a bit high, upper 30s is certainly likely. Is she different
enough from a carrier that the comparison is totally meaningless?
Tom
One thing that nobody else on this thread has mentioned:
In the last year or so there has been discussion in the mainstream press of very fast
mechant ships. I'm not an engineer and I read the articles a while ago. What I
remember is this.
The ships had a hull somewhat similar to a deep V small powerboat hull
They were charachterized by a square stern
They would be built in the 40 to 60 ton range
They could sustain 40 to 45 knots
The proposal was to build them for high value cargo like automobiles.
It occurs to me that the CVNs might very well have this hull design now and if that
were true than the 40 knot speed is well within reason. But as I said I do not have
the knowledge to make more than uninformed specualtion.
Any of you who know more care to either shoot down or support this idea?
Tom Hunter
Eugene Griessel
"Paul J. Adam" <pa...@jrwlynch.demon.co.uk> wrote:
>Plant power is easy. Power in the water is harder. The NIMITZ class are
>four-shaft designs, and there's only so much thrust a propeller can
>generate.
>I'll believe that a "30kt+" Nimitz can make 35-38kt in "we go fast or we
>die" mode, demanding an overhaul and detailed inspection of the
>machinery after such a feat (recall that HMS Princess Royal was
>considered the lame duck of the BC fleet after her all-out speed run
>overloaded the machinery...) But the ability to generate more power
>doesn't automatically translate to increased thrust.
How true, Paul. We start running into nasty cavitation problems, vibration
problems, hull stress problems and a myriad of other little things for every
knot we put on over a certain speed. The efficiency of the propellor is
optimised at the conventional designed maximum cruising speed. At speeds
higher than this this efficiency erodes away - what may have been an 80%
efficient propellor starts dropping a significant couple of percentage point
for every few revs more you make it go.
In short the shp needs to be even greater than calculations for shp show
because slip is increasing dramatically.
Eugene L Griessel eug...@dynagen.co.za
www.dynagen.co.za/eugene
SAAF Crashboat Page - www.dynagen.co.za/eugene/eug3.htm
Thought for the day .......
They never let you live it down. One little mistake! - Nero
M. P. Reed
Dave Welsh wrote:
> Krztalizer wrote in message
> <199804170849...@ladder03.news.aol.com>...
> >Anyone know how fast a Nimitz can go at full speed on all four screws?
> Besides
> >Eisehower's cross-med high speed run, have any others been done with these
> >leviathans?
> >
>
> I note that nobody has quoted a figure.
> Based on the dimensions of the ship I would expect up to 40 knots.
>
I was once told by someone who was there, that when the Pueblo was captured,
the Enterprize, according to what I was told, made 55kts to reach Korea . How
true that is, I have no idea.
Michael P Reed
Dave Welsh
M. P. Reed wrote in message <3537F199...@tdi.net>...
Michael:
Sounds improbable.
The LWL of large carriers is on the order of 1000 ft.
"Hull Speed" = 1.2 to 1.4 times square root of LWL (depends on hull shape)
= 1.3 x 31.62 = 41.1 knots
Above that speed, the ship is literally "digging itself into a hole" because
the
length of the wave pattern it creates exceeds the length of the ship. The
power
required for additional speed increases phenomenally.
Vessels travelling above "hull speed" have to plane in some manner or be
submerged, neither of which applies to a CVN.
Note that 55 kts = a coefficient of 1.74 x sqrt LWL, which is unheard of.
Dave Welsh
dwe...@deltanet.com
Eugene Griessel
Joshua Turner <sh...@umich.edu> wrote:
>Just curious, where does the SS United States fit in to this debate?
>Obviously, the US has a much different hull form from the carriers, is
>just under 1000 ft, and weighs substantially less than the carriers (her
>GRT was 53,000--I can't find a source on her displacement, but it was
>certainly far short of 90K tons). But with 240,000 hp, the US could
>cruise comfortably at 36 knots (average speed on her maiden voyage was
>35.53), and her actual top end was quite a bit higher than that--reports
>differ, but it's been said that she hit 43 kts during sea trails. Even
>if 43 is a bit high, upper 30s is certainly likely. Is she different
>enough from a carrier that the comparison is totally meaningless?
Her maximum recorded measured mile speed was 38.32 knots - achieved during a
series of trials held on the 9th and 10th of June 1952. That's what the
records show. However I am sure you will find a sailor to confirm the 43
knots - if you buy him enough rounds at the bar.
She probably had a better coefficient of fineness than a Nimitz class carrier
- I have not her data handy so am just guessing but I doubt she was anywhere
near as beamy as the Nimitiz.
I notice also that nobody has claimed to have beaten the trans-Pacific record
that has stood since 1972 which was done at an average speed of 33.27 knots.
The US Military has never been shy of claiming records - even the then highly
secret SR-71 was claiming published and ratified records way back in the 60's
and early seventies. Why then is the USN so shy of claiming speed records
with the Nimitz and her sisters?
Eugene Griessel
Tom <zub...@shore.net> wrote:
The Stena company, I believe, has a pair ferries that do 44 knots maximum,
though they cruise at about 40 knots. They are gas-turbine powered catamarans
of about 420 feet in length with a "beam" of about 130 feet. Can carry about
350 cars and more than a thousand passengers. But a catamaran hull-form is a
totally new ball game. The Nimitz (unless the CIA have done some very good
disguising) is a monohull.
John Weiss
During a Dependent's Day cruise one day in the late 80s, the CO of the
Nimitz announced to the masses over the 1MC and 5MC that we were doing 42
knots. Since I had been aboard several times when transiting at 35 knots,
and it _felt_ like we were going significantly faster, I have no reason to
disbelieve him.
Remember, displacement would have been substantially less than full load.
---------------------
John R. Weiss
Seattle, WA
Remove *NOSPAM* from address for e-mail reply
Eugene Griessel wrote in message <35378...@hawk.pix.za>...
>el...@WPI.EDU (Andrew Toppan) wrote:
>
>>Krztalizer (krzta...@aol.com) was seen to write:
>>> Anyone know how fast a Nimitz can go at full speed on all four screws?
Besides
>
>>Various reports indicate speeds of at least 40+ knots, and perhaps 50+.
>>Absurd reports indicate 70+ knots, but are obviously untrue. There's good
>>reason to believe 40+ is possible; theoretical hull speed is 44 knots,
>>IIRC.
>
>To lock horns with the Great Andrew.
>
>I think these figures are patently absurd.
>
<snip>
>
>Thus I must conclude that those who think a Nimitz will do 40 knots are
sadly
>deluded. 40 mph - yes at a giant squeeze with the chief sitting on the
safety
>valve. But not 40 knots. 50 knots its absolute fantasy. Beyond the
>consideration of sane, reasonable and grizzled chief engineers.
Paul J. Adam
In article <6h87p7$o0a$3...@bigboote.WPI.EDU>, Andrew Toppan
<el...@WPI.EDU> writes
>Horsepower limitations of the conventional plant. Nuke plants can put out
>a lot more HP.
Your plant can put out power. Now you need to turn it into useful
thrust. Raw power's useless if all it does is strip the reduction gears,
or make noise as cavitation.
Are the Nimitz-class really engineered to handle half a million shaft
horsepower? Shouldn't be hard to find out if they are, the props alone
would tell anyone listening with sonar.
--
There are four kinds of homicide: felonious, excusable, justifiable and
praiseworthy...
Paul J. Adam pa...@jrwlynch.demon.co.uk
Paul J. Adam
In article <6h872h$o0a$1...@bigboote.WPI.EDU>, Andrew Toppan
<el...@WPI.EDU> writes
>I wouldn't doubt those figures. It's hard to imagine that shp in CV/CVN
>designs has not gone up AT ALL in the 40+ years since FORRESTAL was
>designed. FORRESTALs were at 260,000-280,000 hp; it's rather hard to
>believe they couldn't manage to squeeze just a bit more out of a much more
>modern nuclear plant.
Plant power is easy. Power in the water is harder. The NIMITZ class are
four-shaft designs, and there's only so much thrust a propeller can
generate.
I'll believe that a "30kt+" Nimitz can make 35-38kt in "we go fast or we
die" mode, demanding an overhaul and detailed inspection of the
machinery after such a feat (recall that HMS Princess Royal was
considered the lame duck of the BC fleet after her all-out speed run
overloaded the machinery...) But the ability to generate more power
doesn't automatically translate to increased thrust.
Peter Skelton
I'm not going to weigh into the CVN top speed thing because I do not know
enough about them to comment. Andrew's reasoning is just a bit thin.
About a year ago I did fairly extensive research into WWII destroyer top
speeds. From that I think I know how the government researchers into UFO's
must feel. For example, every incident and trial I could track down gave
tribal destroyers (same thing for the A-I fleets) of 33 knots or less in
fighting trim (only two incidents proovably over 32). Several incidents
cannot be proven, of course and for many others I could only find
horsepower or rpm. I can introduce you to veterans who will swear they made
36 in circumstances where I'm quite positive it was 30 or less.
If we are willing (and I think most of us are) to discount eyewitness
reports, passed on through third to fiftieth parties on a missle, as honest
mistakes and/or urban legend why should we suddenly believe the same sort
of evidence about carrier speed?
"No shitters" have a long and honourable tradition. The slower and fatter I
get now, the stronger and faster I was in my youth.
Nobody is calling anybody a liar.
Pete Skelton
el...@WPI.EDU (Andrew Toppan) wrote:
>Dave Anderer (dand...@udel.edu) was seen to write:
>> "Reports", or "sea stories"? If they're considered legitimate
>> reports, do you have a cite or two?
>
>Reports, typically in the form of
> "I was on the bridge of the cruiser USS XXX and we were doing 30 knots
>when the carrier XXX blew by us doing at least 10 knots better than us"
>
>"I was on the bridge of the carrier USS XXX and saw the knotmeter showing
>XX knots"
>
>etc, etc, etc. They've all been posted here before...
>
>> The only numbers I'm really comfortable with are the trial numbers,
>
>Which, conventiently for you, are not available...
>
>> So, I'm skeptical of many of the high numbers offered in this group.
>
>So you're calling *all* of these people liars? Perhaps some have inflated
>their claims...but did everyone?
>
>--
>Andrew Toppan --- el...@wpi.edu --- "I speak only for myself"
William Hamblen
On 17 Apr 1998 20:38:33 GMT, hil...@morgan.ucs.mun.ca (Dale Hillier)
wrote:
>The highest speed that I have ever head of CVN go is 67 kts, IIRC it was
>Carl Vinson in the IO some years back. I think that we can safely assume
>that 67 kts is rather absurd. However I do agree with Dave's point that
>the power output of CVNs is grossly underrated for the vessel to make
>turns in excess of 35 kts.
The resistance to the movement of a ship through the water varies
roughly as the square of the speed; therefore, the power required
varies roughly as the cube of the speed. If a big ship needs 150,000
SHP for 30 knots, then it would need three hundred thousand for 40
knots and one and a half million for 67 knots.
That's a pretty good overload.
Bloody Viking
Brian Varine (Witch*D...@usa.nospam.net) wrote:
: (granted they were designed a while back but still). I think an SSN
: would have a hard time chasing down most surface vessels in a race. Not
The USS Belknap was able to do 37mph (33 knots) with all 4 boilers in it's
prime. Not bad for 8,000 tonnes, eh? When I was on it, it did 33mph (29
knots) in a full power run. Of course, bearings were overheating and we
had to use "elephant trunk" hoses on the vents to cool the bad bearings.
Oh well, you can't expect a 30-year old clunker to go as fast as it did
off the showroom floor. :) In that way, ships are like cars.
I'd like to see a Nimitz model in it's prime with a brick on the gas
pedal. (The Italian cruise control) It probably attains nearly highway
speed as my guess. Now, that would be impressive, 100,000 tonnes that
can't drive 55! Back in WW 2.0, the carriers would turn into the wind and
floor it for flight ops. Do modern carriers turn into a headwind? I know
they tend to floor it though it's not necessary. The Belknap got some
petrol from a carrier while they were slingshoting planes off at night.
Nothing like those 2 blowtorches coming out the arse ends of the planes!
--
CAUTION: Email Spam Killer in use. Leave this line in your reply! 152680
"Sometimes the best psychiatrist is a flaky cardiologist"
2368146 bytes of spam mail deleted. http://www.wwa.com/~nospam/
Jim McLaughlin
On 17 Apr 1998, Krztalizer wrote:
> Anyone know how fast a Nimitz can go at full speed on all four screws? Besides
> Eisehower's cross-med high speed run, have any others been done with these
> leviathans?
There are lots of rumors and little available public hard
information.
Stennis just made a very fast very long transit departing Norfolk
26 Feb arriving Hormuz, though Med, Suez slowdown, and Red Sea, arriving
Hormuz about 8 March IIRC.
Given the delays inherent in a Suez transit, that is a very fast trip.
Several of the battlegroup's smallbiys departed Norfolk 3 days prior to
Stennis. Stennis passed them in eastern Atlantic / western med.
Jim McLaughlin These opinions are mine, mine, mine!
Portland, OR And not anybody else's. So there.
Remove Anti Spam Device *!!* From Address Before Replying
Bloody Viking
Guy Derdall (battl...@sk.sympatico.ca) wrote:
: Her reactors much like the older steam plants usually have an overload in
: them
: I know the Iowa's was 254,000 shp on overload.
: This is probably how the Nimitz's can go 40+ knots. Many people have said
: they can, but who knows right?
: My bet is on the 40+ speeds. 50+ being a little excess.
My pet guess is about 45mph (40 knots) based on length where water
"aerodynamics" favour longer ships and the power supply. The Iowa models
has powerplants used in carriers at the time too. It's sort of like the VW
Quantum and Audi 4000 cars of 1987 as an analogy. The propulsion system is
the same but the body is different. (I own a 1987 Quantum as of now.) In
any case, 45mph (40 knots) is pretty good for a 100,000 tonne vehicle. The
Titanic weighed 80,000 tonnes and was doing 27mph (25 knots) when it
sideswiped that iceberg.
Don't you hate overdriving your headlights?
LCDR1635
>Back in WW 2.0, the carriers would turn into the wind and<BR>
>floor it for flight ops. Do modern carriers turn into a headwind
While flight ops are still normally into the wind, I recall at least one
occasion when I was onboard NIMITZ (86-88) where we did downwind recoveries.
Weather upwind was closing to near 0-0 conditions so we turned downwind and
pushed the speed up enough to get 20kts over the deck, and recovered.
John H. Eckhardt
It's not my spelling or grammar that's so bad. It's my typing.
Krztalizer
>> Shouldn't be hard to find out if they are, the props alone
>would tell anyone listening with sonar.
>
>
Paul,
As you know, 4-CZ sonar contact is quite common with these leviathans.
In fact, they often mask the sounds of the rest of the inner zone ships when a
carrier is truly making flank. NOTHING louder than a CV, with the exception of
an oil-drilling platform.
G
Krztalizer
>
>Vessels travelling above "hull speed" have to plane in some manner or be
>submerged, neither of which applies to a CVN.
>
>Note that 55 kts = a coefficient of 1.74 x sqrt LWL, which is unheard of.
>
>Dave Welsh
NOW, you're talking! See, the reason I asked this question is that we were
spotted during our under-Africa transit by the US tin can USS Hull. Guys from
that ship reported that we (Nimitz-twin USS Eisenhower) were dug in on the
stern, and our bow was coming out of the water from wave to wave. The is a
photograph of us passing, and at the moment of the shutter, we are going from
crest to crest on the waves, with ALL of the bow clear. Now, what kind of
speed does THAT take?
Plus, anyone serving on a Nimitz-class will agree that when all four screws get
cranking (a rare event), the stern digs down as much as 10 feet lower in the
water. During low speed transits, the stern deck is dry -- at much higher
speeds, froth and splash drench anyone trying to fish from the fantail (another
rare event, but one our Skipper loved to do).
Gordon
TMOliver
Dave Anderer wrote:
>
> On 17 Apr 1998 18:39:31 GMT, el...@WPI.EDU (Andrew Toppan) wrote:
>
> >Reports, typically in the form of
> > "I was on the bridge of the cruiser USS XXX and we were doing 30 knots
> >when the carrier XXX blew by us doing at least 10 knots better than us"
> >
> >"I was on the bridge of the carrier USS XXX and saw the knotmeter showing
> >XX knots"
> >
> >etc, etc, etc. They've all been posted here before...
>
> accept them completely, 100%, at face value. There can be problems
> with eyewitness testimony - be they about plane crashes or vehicle
> speeds.
>
> >
> >
> >Which, conventiently for you, are not available...
>
> USN keep them secret...
>
> >
> >
> >So you're calling *all* of these people liars? Perhaps some have inflated
> >their claims...but did everyone?
>
> believe the engineering data and the USN's historical choices in ship
> design make it unlikely the high speeds quoted are correct.
>
> Physics is physics.
I'm with you lad, and I suspect a Hell of lot of the anecdotes to which
Andrew is subscribing are in the same category as eyewitness statements
to the loss of TWA800, largely based on memory inflated by distance and
desire.
The overloaded ESSEX conversion had to stretch to hit 31 knots by the
early 60s. The FDR/MIDWAY/CORAL SEA, good for 33.5 or so at builders
trials, were bound to have suffered a drop as displacement/wetted area
went up with the addition of angled decks and supefluous cr*p hung about
them. The F&S hogs were never noted for making 33, which fits their
shp/hull/combos. Big E was faster, but not by a great deal. I would
not accept any anecdote not backed by the navigator's plot which would
put her at more than 36 (with 34-35 more likely), unless running North
on the Gulf Stream, a well knoewn trick used by some to pump their
numbers. The newer CVs? No faster than the E, if as fast. No need to
be. 30 kts. over the deck may cause a "heavy" a/c to have to pump some
JP over the side, but from an old wind chaser, there's no point in
chasing the wind at higher speed than the escorts can keep station.
An earlier poster cited the real advantage of a nuke, "high" (read 28
knot) speed transits. Another advantage of a 'big" CV (and many thanks
to the RN for those loverly hurricane bows) remains the ability to
operate at high speed in sea states which cause little boys to sup
vertically and strap themselves in their racks. Rig fiddle boards,
steward!
High speed tales may be classified as Category II sea stories, requiring
that dungarees be rolled to ankle height before reading. Cat I tales
require placing the right index finger alongside the nose and rolling
one's eyes slightly. Cat III's are not told until the muted note of
"last call" has resounded across the barroom or the young lady into whom
one is attempting to slip scores about a 3.87 or higher on the dumb
blonde gullibility meter
--
TMOliver AKA El Pelon Sinverguenza
Attributed to the sagacious but concupiscent Benjamin Franklin...
"Three people can keep a secret if two are them are dead."
These days, any hope for secrecy requires getting rid of the third!
Random
On Fri, 17 Apr 1998 17:42:53 -0700, "Dave Welsh" <dwe...@deltanet.com>
wrote:
snip
>>>
>>
>>I was once told by someone who was there, that when the Pueblo was
>captured,
>>the Enterprize, according to what I was told, made 55kts to reach Korea .
>How
>>true that is, I have no idea.
>>
>>Michael P Reed
>
>
>
>Michael:
>
>Sounds improbable.
>The LWL of large carriers is on the order of 1000 ft.
>
>"Hull Speed" = 1.2 to 1.4 times square root of LWL (depends on hull shape)
>
>= 1.3 x 31.62 = 41.1 knots
>
>Above that speed, the ship is literally "digging itself into a hole" because
>the
>length of the wave pattern it creates exceeds the length of the ship. The
>power
>required for additional speed increases phenomenally.
>
>Vessels travelling above "hull speed" have to plane in some manner or be
>submerged, neither of which applies to a CVN.
>
>Note that 55 kts = a coefficient of 1.74 x sqrt LWL, which is unheard of.
>
>Dave Welsh
>dwe...@deltanet.com
>
I suppose you could try getting the bell log and deck log via the
Freedom of Information Act and see what they recorded. You know the
date, it might be worth a try.
random
Eugene Griessel
el...@WPI.EDU (Andrew Toppan) wrote:
>Eugene Griessel (eug...@dynagen.co.za) was seen to write:
>> from nuclear or gas turbine or conventional steam. I have never, in 20 years,
>> seen a figure other than 260 000 to 280 000 quoted for these vessels.
>SO WHAT? The US Navy has said, time and time again, that horsepower and
>speed figures for nuclear ships are not released. The 280,000/30+ is
>admittedly not the true hp/speed. The fact that you've seen it a lot is
>NOT proof that these figures are correct.
Observers have for years been making extremely accurate assessments of Soviet
warship's horsepower from looking at photographs of the wakes. I would assume
these same gentlemen would have spoken out be now, don't you? After all this
class has been around for some years.
>> Where pray tell did I quote 30 as a true top speed? Please show me? I can
>> recall using 34 knots in my calculation. That is the speed most reference
>OK, you said 34. The difference from 30 is not particularly large nor
>relevant. 4 knots is a good margin for hull fouling, load differences,
>etc. anyway.
No the difference is not large or relevant. It only represents an increase of
about 85 000 shp, which I am sure most will agree is absolutely nothing.
Except that seems to be around the total installed power of a Sprucan - does
it not. Do the sums Andrew. To speed a Nimitz from 30 knots to 34 knots will
take at least 85 000 shaft horse power.
>> How did the "people who were there" figure out the speed? How does anyone
>> tell the speed of a ship? Measured mile is the only truly accurate figure.
>> Don't quote the log at me - those thing have large errors when it comes to
>> instaneous readings. Logs are only useful for speed measurement over a
>So you're telling me that no log is ever accurate? Then why bother having
>them?
Logs are accurate enough on distances. Instantaneous speeds are another thing
totally. I have seen respected logs by top makers momentarily swing 6 or 7
knots either way around a true base speed. It then becomes a hell of a job
to convince the seamen that the ship was not actually doing that speed. One
of the reasons that revolutions have been held a far more accurate way of
gauging speed.
>> I'm not sure I follow your reasoning here Andrew. The Forrestal class have
>> always had a published top speed of 34 knots except for Forrestal herself
>> which was 33 knots. I imagine these were obtained in standard conditions over
>> the measured mile. Forrestal had different machinery to her sisters and was
>What I'm saying is that it's almost unbelievable that in 40+ years of
>carrier design we haven't manged to squeeze a single extra horepower out
>of the plants. The ships are longer, the displacement is much higher, but
>nobody along the way thought to upgrade the propulsion? Ridiculous.
What I am saying is that the installed plant for a Nimitz has to be,
horsepower for horsepower considerably larger than that of a Kitty Hawk.
Larger, lower speed turbines, larger reactors than the boilers. One does not
just "sneak in" a few extra hundred thousand horses. One has to increase the
machinery space considerably. And as any designer who has ever tried to
design a naval vessel will tell you the fight is on from the word go for space
on a warship. Everybody want room for their missiles, planes, radars etc.
mostly at the expense of the machinery plant. Now I roughly guestimate that
the machinery plant required (and this is from experience on fast ships only)
to get Nimitz up to 40 knots would occupy approximately between a sixth and a
fifth of the hull space. Does it?
>Hell, Friedman claims the NIMITZ class went DOWN in shp from 280,000 to
>260,000. Tell me another funny story...
I am sorry Andrew - I do not see this as a funny story. You are asking us to
believe that it has to be faster merely because it is newer. That is a funny
story.
>> So point me to any sources that differ on shp for the Nimitz class.
>The whole point is that the published figures for the class are
>INTENTIONALLY MISLEADING. Your entire argument is based on those figures,
>and is therefore bogus.
Keep going like this and you will be in the Rivero/Goddard camp soon. Yes
Janes et al do sometimes get slightly wrong figures. Especially as I pointed
out before, warship speed is no absolute. But to date nobody has come with
better data on average. If the Nimitz could do these incredible speeds surely
some slightly hostile navy would have tracked her at them and published the
figures by now. The intentionally misleading epithet is grasping at straws -
because any naval architect could sit down and make the calculations as to
likely speeds, powering, etc. Others, skilled in the art, check photographs
of wake and waves - and from that alone make very good estimates of powering.
A navy intentional publishing "misleading" figures of that magnitude (and God
knows why they should bother about something as mundane as speed) would soon
get shown up by foreign observers casting doubts on published figures.
Eugene Griessel
el...@WPI.EDU (Andrew Toppan) wrote:
>Dave Anderer (dand...@udel.edu) was seen to write:
>> Let's take some other data points. LWL of CVA59 was 990'. That
>> implies a maximum speed of 41 knots. I've never heard any claim the
>> conventional carriers were/are that fast. Yet based on hull length
>Horsepower limitations of the conventional plant. Nuke plants can put out
>a lot more HP.
It has the same sorts of limitations. It is not above normal physical
restraints. In fact a nuke is a very bad way of generating steam - as any
nuclear engineer will tell you. In a PWR you have much higher pressures than
in a normal oil-fired boiler - and you end up with wet steam at a much lower
pressure. It only advantage is the fact that you do not need to lug oodles of
oil around. The power density of even the very best nukes (sodium-cooled fast
breeders) is pathetic compared to an oil-fired boiler. Something in the
region of 640 kW per litre for the core. PWR's run around 110 kW per litre
for the core. Add the volume of the containment and you end up with something
less power dense than the engine in the family saloon.
>> tend to be fairly accurate. While they equivocate on speed,
>> non-nuclear power numbers seem to represent reality. So let's make
>There's the key - *non nuclear* numbers. You've got no nuclear numbers,
>and the assumption that nuke and non-nuke numbers are the same is probably
>not valid.
I have plenty of valid nuclear numbers - maybe not dead accurate for a
military reactor, but close enough to extrapolate.
What you cannot prove is that the engineering spaces on a Nimitz class are
three time larger than that of a Kitty Hawk class - as they would have to be
to attain 40 knots.
MICOMA
In article <Pine.GSO.3.96.980417...@user1.teleport.com>, Jim
McLaughlin <baldyjim@tele*!!*port.com> writes:
>Given the delays inherent in a Suez transit, that is a very fast trip.
>Several of the battlegroup's smallbiys departed Norfolk 3 days prior to
>Stennis. Stennis passed them in eastern Atlantic / western med.
IIRC, I read that Stennis met her small boys in the Gulf, or just before
entering the Gulf. Something about the early departure so that they would
arrive together about the same time in the region - with less wear & tear on
the non-nuke escorts.
Mike Weeks
JerryLee
On Fri, 17 Apr 1998 16:14:52 GMT, eug...@dynagen.co.za (Eugene
Griessel) wrote:
:el...@WPI.EDU (Andrew Toppan) wrote:
:
:>Krztalizer (krzta...@aol.com) was seen to write:
:>> Anyone know how fast a Nimitz can go at full speed on all four screws? Besides
:
:>Various reports indicate speeds of at least 40+ knots, and perhaps 50+.
:>Absurd reports indicate 70+ knots, but are obviously untrue. There's good
:>reason to believe 40+ is possible; theoretical hull speed is 44 knots,
:>IIRC.
:
:To lock horns with the Great Andrew.
:
:I think these figures are patently absurd.
:
:What is the speed of a ship? Most landlubbers and many salts seem to think a
:ship has one true maximum speed. Yes, there is the measured mile which
:attempts to measure such a speed. But speed is tied up with tonnage, the
:"bend" of the hull, the surface of the hull and the air and sea temperatures
:during the trial run. Even the salinity of the water has its effects.
:
:Looking at the Nimitz class, I cannot calculate the power requirements because
:I have no data other than that I get out of Janes - which does not allow me to
:calculate, with any real accuracy, the wetted area and hence the total
:resistance.
:
:So I resort to the old Admiralty coefficient method.
:
:When one sets out to design a ship, one of the first things needed is the
:horsepower requirement so that a suitably large space can be designed into the
:hull for the machinery. For this one uses one of a number of methods - but
:the Admiralty Coefficient works well enough. Using the admiralty coefficient
:and working backwards from the advertised horsepower, speed and tonnage of a
:Nimitz class vessel I arrive at a figure around 300 - which is fairly
:reasonable. It's what a vessel of that shape could be expected to have.
:Using around 300 for AC and 93000 tons at a speed of 34 knots I find the
:beast will need about 280 000 shp. To push it up to 40 knots I will need 547
:379 shp and to get her to 50 knots will need 855 284 shaft horse power.
:
:I doubt that she can put out that sort of power. If I calculate the other
:way, taking her tonnage and speed and advertised power I start getting AC
:figures that not even a torpedo manages to achieve.
:
:Thus I must conclude that those who think a Nimitz will do 40 knots are sadly
:deluded. 40 mph - yes at a giant squeeze with the chief sitting on the safety
:valve. But not 40 knots. 50 knots its absolute fantasy. Beyond the
:consideration of sane, reasonable and grizzled chief engineers.
Not an engineer, but a trick memory and a propensity for reading some
material some people would find strange..
I could not recreate the equations, but the figures given for the hull
coefficient for a ship such as the Nimitz IIRC would require infinite
horsepower somewhere in the 40 kt range.. not really realistic.
rgds j.
AGCS Ret
The Ice,-NHK,NUQ,BIKF,PMDY,-"O"boat,-Big"E"
JerryLee
On Fri, 17 Apr 1998 18:18:47 GMT, eug...@dynagen.co.za (Eugene
Griessel) wrote:
:dand...@udel.edu (Dave Anderer) wrote:
:
:>On Fri, 17 Apr 1998 16:14:52 GMT, eug...@dynagen.co.za (Eugene
:>Griessel) wrote:
:
:>>So I resort to the old Admiralty coefficient method.
:
:>Could you talk a little about this method? I'm not familiar with it,
:>but it sounds interesting. It must be accurate, because it supports
:>"my" conclusions. :)
:
:The actualy formula is simple. It is represented by the tonnage raised to the
:power 0.6666666 multiplied by the speed (in knots) cubed and then the shebang
:is divided by the AC to give shaft horsepower. The AC depends on a lot of
:things and is usually taken from a graph of lengths. The AC runs from about
:270 for the slimmest of destroyers through to about 600 for a wallowing tub of
:a merchantman. There is a preliminary design formula to calculate a more
:accurate AC but for this model data is needed. Which, for the Nimitz, I do
:not have.
:
It has been some time, and I really don't remember where I read it.
There was a complex formula having to do with hull design. Something
similar to the calculations done determining the airflow over an
aircraft surface.. Except for hull design, vice acft, the medium was
non compressable. Is this what you are referring to, or am I
remembering something the Cray types were playing with next door at
NASA...
JerryLee
On Fri, 17 Apr 1998 20:04:21 GMT, bda...@twr.org (Bill Damick) wrote:
:
:Short run top speed aside - the really great thing about being afloat
:on a nuke ship was that it could maintain flank speed a whole lot
:longer than an oil-burner. I was on the USS California back in 1981,
:and we made a transit from Rota around Africa the long way up to GONZO
:station at an average speed of somewhere around 28kts - all by our
:lonesome. Took around 3 weeks more or less. Would love to see you
:try that on a tanker-teathered CG, CA, or CV! The down side was that
:is was pretty miserable down in the engine hole. The up side was a
:nice breezy passage during shellback ceremonies.
:
:BD
It also gets one back to port rather well.. We left our cans spinning
in the wake, with a SSN for escort, and were quaffing suds days before
the can sailors.
Eugene Griessel
jbar...@nospam.sjm.infi.net (JerryLee) wrote:
Heavens - this "formula" is more a rule of thumb. It's what we used to use
merely to determine a ballpark figure for horsepower in the preliminary design
stages. Nowadays with the rise of computing power I have no doubt far more
accurate methods are used. Those days everybody would gather around a table
and say things like:
TAS: we need room for 60 AS Torpedoes, 10 helicopters, 10 mortars and our
sonar gear
Guns: we need three triple 16 inch turrets and lots and lots of little guns.
Radar: we need .....
And from this the designers had to try and deliver a hull, within reason, to
accomodate where possible the conflicting demands. I sat in on only one such
conference, determined to plan a corvette. We always seemed to start with a
vessel a hundred foot long and end up with a thing that would make an Iowa
cringe in shame. Every damned department was determined to fill the hull with
everything they could lay their grubby paws on - at the expense of every other
department (all insisting what they wanted was absolutely essential). The
engine room crowd (myself) were treated like lepers if we even asked for a
foot of space to fit an outboard to the thing. These bun-fights were known as
"preliminary design conferences" and convinced me that they were the absolute
worst way to design a warship. Since then I have held the view that a good
hull and machinery should be the first priority - and then fitted with
whatever weapons it could reasonably accomodate. But I am talking
pre-digital, pre integrated circuit chip, computers as well. Massive old
analogue things for the guns etc that needed space, power and oodles of
cooling.
So this formula was basically used for a ballpark figure to know how much
space was needed in the hull for the powerplant at the early stages. If the
demands for speed were such that the ship was half engine room it was nice to
know this before you got out the old set square (no cads either back then).
Tom
Eugene Griessel wrote:
> Tom <zub...@shore.net> wrote:
>
> >One thing that nobody else on this thread has mentioned:
>
> >In the last year or so there has been discussion in the mainstream press of very fast
> >mechant ships. I'm not an engineer and I read the articles a while ago. What I
> >remember is this.
>
> >The ships had a hull somewhat similar to a deep V small powerboat hull
>
> >They were charachterized by a square stern
>
> >They would be built in the 40 to 60 ton range
>
> >They could sustain 40 to 45 knots
>
> >The proposal was to build them for high value cargo like automobiles.
>
> >It occurs to me that the CVNs might very well have this hull design now and if that
> >were true than the 40 knot speed is well within reason. But as I said I do not have
> >the knowledge to make more than uninformed specualtion.
>
> >Any of you who know more care to either shoot down or support this idea?
>
> The Stena company, I believe, has a pair ferries that do 44 knots maximum,
> though they cruise at about 40 knots. They are gas-turbine powered catamarans
> of about 420 feet in length with a "beam" of about 130 feet. Can carry about
> 350 cars and more than a thousand passengers. But a catamaran hull-form is a
> totally new ball game. The Nimitz (unless the CIA have done some very good
> disguising) is a monohull.
>
> Eugene L Griessel eug...@dynagen.co.za
Eugene,
This proposal was for a monohull. Again I don't know how workable it is but I know I saw
it.
Tom Hunter
Peter Skelton
eug...@dynagen.co.za (Eugene Griessel) wrote:
<snip>
>What you cannot prove is that the engineering spaces on a Nimitz class are
>three time larger than that of a Kitty Hawk class - as they would have to be
>to attain 40 knots.
It strikes me that an oil burning carrier wold have to carry a lot of fuel
around that a Nuke might not need. That ten thousand tonnes can be used in
other ways and, I suspect, there would be enough mass available to give a
few extra knots. While oil plants give more power per cubic foot than
nukes, they require large uptakes and the fuel itself occupies a lot of
volume.
Where the balance is will depend on how highly the designer values avgas
capacity compared to speed. (or something like that.)
--
Peter Skelton
Skelton & Associates
613/634-0230
p...@adan.kingston.net
Jim Kelly
In the course of my historical research into my ship's
history I was made aware of a situation regarding USS
ENTERPRISE (CVN-65). RUSH was one of her escorts (TG135.2).
The situation noted was her (ENTERPRISE) hurried departure
from Norfolk so as to be off Mayport to pick up her escorts
and from that point on to station off Cuba as part of the
quarantine, a.k.a. "Cuban Missile Crisis".
A former CO in our ship told me that the "Big E" departed
Norfolk at night and arrived off Mayport the next morning at
0800. This must be a matter of record with deck logs
although I have never pursued the matter. Someone may know
the facts, the distances involved, I do not, but I am
intrigued by the possibilities.
With no need to allow escorts keep station, ENTERPRISE could
go flank for the run down (against the Gulf Stream) to
Mayport. Any guesses as to time & distance here?
CJK
Eugene Griessel
Jim Kelly <cats...@freewwweb.com> wrote:
Distance is around 550 nautical miles. Depending on what "off Mayport"
meant.
Joshua Turner
Bloody Viking wrote:
>
> Guy Derdall (battl...@sk.sympatico.ca) wrote:
> : Her reactors much like the older steam plants usually have an overload in
> : them
> : I know the Iowa's was 254,000 shp on overload.
> : This is probably how the Nimitz's can go 40+ knots. Many people have said
> : they can, but who knows right?
> : My bet is on the 40+ speeds. 50+ being a little excess.
>
> My pet guess is about 45mph (40 knots) based on length where water
> "aerodynamics" favour longer ships and the power supply. The Iowa models
> has powerplants used in carriers at the time too. It's sort of like the VW
> Quantum and Audi 4000 cars of 1987 as an analogy. The propulsion system is
> the same but the body is different. (I own a 1987 Quantum as of now.) In
> any case, 45mph (40 knots) is pretty good for a 100,000 tonne vehicle. The
> Titanic weighed 80,000 tonnes and was doing 27mph (25 knots) when it
> sideswiped that iceberg.
Actually, she weighed 66,000 tons and was making about 21 knots at the
time of the accident. And Titanic only had 46,000 hp.
Bradley Perrett
William J Bollinger wrote in message
<3537ba2b....@news.mindspring.com>...
>A Mk3 Mod7 SINS in my day. That's a gyro-stabilized platform with
>accelerometers. When kept properly aligned, it was pretty accurate. We
>kept ours properly aligned. It said 40+ knots.
What were you on, and can you remember the period over which that was
measured?
Brad
Andrew Toppan
I'm not going to bother replying to every one of these posts. I will
simply make a few general points.
I'm far from convinced that USN would spend billions designing nuke plants
but fail to squeeze even a single extra HP out of the plant. Yet most
everyone here seems to be merrily going along with that assumption. Don't
you think the designers might be competent enough to improve the plant
just a bit in 50 years?
Since WWII we've wanted CV speed to (at the least) remain constant, while
the ships have grown. Larger ships and constant speed mean more
horsepower - but people are saying the HP hasn't changed any. Constant HP
and increasing ship size indicate DECREASING ship speed - something we
certainly have not seen in CV/CVNs. The constant HP assumption is just
not realistic.
That example showing how cruiser/destroyer HP has stayed constant since
WWII is cute, but misses the point. Before/during WWII we wanted our
destroyers (& the Atlantas) to do 36+ knots; postwar (Spruances et al) 30
was acceptable. Naturally, when speed goes down the need for increasing
HP goes away.
In the last four years I have seen this discussion go on at least thrice
here and twice in other forums. I've seen at least 24 people cite
examples from personal experience where the CVN was exceeding the 30-34
knot "limit" people here are trying to impose. Even if we throw out 50%
of those reports to account for "enhancement" of the stories, and throw
out 50% of the remainder to account for "inaccurate" instruments, we've
still got a pile of reports of CVNs "violating" your speed "limits". How
do you account for these? All liars?
Also, note that the only post from people who have actually served in CVNs
are in agreement that the 30 knot speed is silly.
It's interesting to see how the general opinion of the newsgroup changes
with time. Last time we had this argument the "40+ knot club" drowned
out those believing in lower speeds. This time the mix of participants is
different, and the "30 knot club" is drowning out all arguments to the
contrary. I'm sure we'll do this again in a year and the outcome will
have changed yet again, depending on who feels like shouting loudest.
TJG
In article <6h7r57$4lv$1...@bigboote.WPI.EDU>, el...@WPI.EDU says...
>
>Krztalizer (krzta...@aol.com) was seen to write:
>> Anyone know how fast a Nimitz can go at full speed on all four screws?
Besides
>
>Various reports indicate speeds of at least 40+ knots, and perhaps 50+.
>Absurd reports indicate 70+ knots, but are obviously untrue. There's good
>reason to believe 40+ is possible; theoretical hull speed is 44 knots,
>IIRC.
>
>> leviathans?
>
>
>--
>Andrew Toppan --- el...@wpi.edu --- "I speak only for myself"
>US Naval & Shipbuilding Museum/USS Salem Online - http://www.uss-salem.org/
>Naval History, World Navies Today, Photo Features, Military FAQs, and more
>Railroad Rosters & Photo Features --- http://membrane.com/~elmer/rail/
Andrew,
Since you seem to be one of the more responsible posters here, what do you
think would be the limiting factor on a ship's speed? Would it be hull speed,
fouled hull speed, machienery (here reactor) output? Or could it be something
else which cannot be analyzed properly in a forum such as this because of
the dearth of information? I was thinking of such things as hull
vibrations from screw interactions, operation envelope limits for keeping
the deckload from being dumped during normally anticipated changes in
course (normal rudder drift, normal helm corrections for sea conditions), or
even such machienery limits as torque limits on the main shafts?
Perhaps that could be why some people say the actual top speed is so much lower
than what would be apparent from a back-of-the-envelope calculation.
--
****************************************************
Official Only When Embossed with Comptroller's Pseal
****************************************************
William Hamblen
On Fri, 17 Apr 1998 19:28:25 -0400, Tom <zub...@shore.net> wrote:
>The ships had a hull somewhat similar to a deep V small powerboat hull
>They were charachterized by a square stern
>They would be built in the 40 to 60 ton range
>They could sustain 40 to 45 knots
You couldn't have a hull form like that on a big ship because then the
draft would be too great to enter any harbor we have. Also you are
going to have to be able to drydock the ship to repair underwater
damage. Pictures of the ENTERPRISE in building dock have been
printed. They show a broad hull with little rise. The big power
savers in the hull form are the transom stern and the bulbous bow.
Eugene Griessel
el...@WPI.EDU (Andrew Toppan) wrote:
>I'm not going to bother replying to every one of these posts. I will
>simply make a few general points.
>I'm far from convinced that USN would spend billions designing nuke plants
>but fail to squeeze even a single extra HP out of the plant. Yet most
>everyone here seems to be merrily going along with that assumption. Don't
>you think the designers might be competent enough to improve the plant
>just a bit in 50 years?
It's not a case of squeezing a few extra horsepower, unfortunately. It's a
matter of squeezing tens of thousands of horsepower. For every knot of speed
over 30 knots is costing you tens of thousands of horsepower. Can the USN
design and build a steam plant putting out 500 000 shp or 1 000 000 shp?
Undoubtedly. The technical knowhow was there at the time these plants were
designed. Which was in the middle sixties. (And if you followed the saga at
the time it was often touch and go. The fiscal cutbacks often threatened not
only this reactor program but the class of ship as well.) Would they want to
and would there be a compelling need for it - and even more importantly -
would the money be available for these speed and power increases? The Vietnam
war was beginning to bite into the money available for new programs.
These reactors were an order of magnitude larger than anything the USN had
previously developed. And reactors are dangerous things - you can get large
amounts of power out of tiny cores, but the geometry of those cores becomes
increasingly difficult to control. Thus you go for some middle path with a
larger core, lower power density and a better chance of keeping the beast
tamed. I can with reasonable certainty state that the physical size of these
reactors (A4w/A1g) was much larger than previous naval reactors - though they
did not need to be (if you did not mind a good chance of reactor catastrophe
and for all his failings Rickover was a fanatic when it came to safety). Was
the power density higher than the previous generation - I concede there is a
good chance that it was. But the technology that developed the Nimitz's
reactors was around before you were born, Andrew!
The turbines also were new territory. Large slow wet steam turbines. Dunno
if you have studied turbine blade design - but look at the differences between
superheated steam and non-superheated. Also look at a steam table and see the
difference in heat energy in the types of steam. So for the same power output
as the Kitty Hawk turbines you needed a lot more physical space. All the
while the machinery spaces are growing - taking up vital war material space.
All for some arcane desire to get this colossus to do what few MTB's have ever
achieved. Not only that - the vital elements of the rest of the force and the
fleet train would have no hope in keeping up. Why? Why build a vulnerable
ship that can get there long before its protection can?
>Since WWII we've wanted CV speed to (at the least) remain constant, while
>the ships have grown. Larger ships and constant speed mean more
>horsepower - but people are saying the HP hasn't changed any. Constant HP
>and increasing ship size indicate DECREASING ship speed - something we
>certainly have not seen in CV/CVNs. The constant HP assumption is just
>not realistic.
Not necessarily. Larger ships need more horsepower, certainly - but the hull
shape also plays a large role as do the propellors. And as Paul so nicely
pointed out - one cannot merely keep adding horsepower. There comes a point
were an infinite increase in horsepower will not bring an inch more in speed -
and in fact the application of more revolutions may actually slow the ship
down as more of the propellor blade faces run in vacuum.
>That example showing how cruiser/destroyer HP has stayed constant since
>WWII is cute, but misses the point. Before/during WWII we wanted our
>destroyers (& the Atlantas) to do 36+ knots; postwar (Spruances et al) 30
>was acceptable. Naturally, when speed goes down the need for increasing
>HP goes away.
So why do we want the carriers to go so much faster then?
>In the last four years I have seen this discussion go on at least thrice
>here and twice in other forums. I've seen at least 24 people cite
>examples from personal experience where the CVN was exceeding the 30-34
>knot "limit" people here are trying to impose. Even if we throw out 50%
>of those reports to account for "enhancement" of the stories, and throw
>out 50% of the remainder to account for "inaccurate" instruments, we've
>still got a pile of reports of CVNs "violating" your speed "limits". How
>do you account for these? All liars?
I have previously refrained from taking part in these discussions because I
thought the absurdity would become obvious - I also did not take part in the
ever-speedier Seawolf discussions for the same reasons. As to people claiming
high speeds - I can bring you virtually entire crews who claim speeds that I,
as the chief engineer, knew were patently impossible. Its often difficult to
convince the deck branch that a 34 knot ship cannot just leap ahead to 40
knots even if the patent log needle did momentarily flick up to that speed.
>Also, note that the only post from people who have actually served in CVNs
>are in agreement that the 30 knot speed is silly.
Yes - I agree fully, 30 knots is silly. But not nearly as silly as 40 knots.
If Captain Richardson the Third himself posted on this ng that the Nimitz
could do 40 knots I would not believe him unless he gave me measured mile
documentation to back up his claim. I notice you have refrained from
addressing my questions as to horsepower needed to push this hull to the
speeds you are claiming it capable of. My second set of calculations did not
rely on any previously published horsepower. You did not challenge them at
all?
>It's interesting to see how the general opinion of the newsgroup changes
>with time. Last time we had this argument the "40+ knot club" drowned
>out those believing in lower speeds. This time the mix of participants is
>different, and the "30 knot club" is drowning out all arguments to the
>contrary. I'm sure we'll do this again in a year and the outcome will
>have changed yet again, depending on who feels like shouting loudest.
Popular opinion (or even majority opinion) does not necessarily make things
true. In the first place we have the absurdity of the USN keeping the true
top speed secret for more than 20 years. Why? It makes the TWA800 cover-up
certainly begin to look like it could be true, does it not? And let's face it
- everytime one of these carriers went anywhere during the cold war they had a
bevy of Soviet intelligence ships and Soviet Elint aircraft mulling about.
First time anyone of them hit 40 knots it would have made the Russian naval
press - and I used to get security briefing from those writings for quite a
number of years. In fact I found out some things about my own Navy I never
knew from them. Nothing on the Nimitz class able to run at 40 knots.
Meanwhile lots of other far more vital intelligence data about those ships has
come to light. But the speed is kept under wraps as the most closely guarded
secret the USN has. To what avail? What have they been hiding for more than
20 years - and perhaps even closer to 30 years given that Nimitz was laid down
in 1968.
Eugene L Griessel eug...@dynagen.co.za
www.dynagen.co.za/eugene
SAAF Crashboat Page - www.dynagen.co.za/eugene/eug3.htm
Thought for the day .......
Professional charity - the milk of human blindness.
Andrew Toppan
> shape also plays a large role as do the propellors. And as Paul so nicely
> pointed out - one cannot merely keep adding horsepower. There comes a point
> were an infinite increase in horsepower will not bring an inch more in speed -
Dammit, I'm quite aware of this, and quite aware that it's not relevant to
whether a CVN can do 40 knots. By your own statements it is possible to
reach this speed if enough power is applied.
> So why do we want the carriers to go so much faster then?
Lemme see...
So our CVN can make a high speed transit if we must, regardless of escorts.
So our CVN can spend all day dashing about the ocean keeping the wind over
the deck while the rest of the battlegroup steams along at a more-or-less
constant speed and course, and at the end of the day the CVN hasn't been
left behind. If our CVN needs 30 knots over the deck and the group is
transiting downwind at 20 knots, the CVN either makes 50 knots in the
direction of transit, or turns around into the wind for a while, then runs
to catch up. Either way somewhat more than 30 knots would be nice.
Please note I'm NOT saying CVN's are doing 50, 60 or 70 knots constantly,
or even for a short time. I'm just saying that something more than 30-34
knots is not too unreasonable. Hell, if an IOWA can do 35 (admittedly
under abnormal conditions), a CVN ought to be able to do the same, or
better.
> thought the absurdity would become obvious - I also did not take part in the
> ever-speedier Seawolf discussions for the same reasons. As to people claiming
So who is the liar on Seawolf? Is the Navy a liar when they say she broke
the previous underwater speed record (44.7 knots)? Or is that 44.7 knot
record a lie?
> addressing my questions as to horsepower needed to push this hull to the
> speeds you are claiming it capable of. My second set of calculations did not
> rely on any previously published horsepower. You did not challenge them at
> all?
It's Saturday, I have no interest in figuring out math. I do enough of
that during the week.
Paul J. Adam
In article <6hak3l$n9b$7...@bigboote.WPI.EDU>, Andrew Toppan
<el...@WPI.EDU> writes
>I'm not going to bother replying to every one of these posts. I will
>simply make a few general points.
>
>I'm far from convinced that USN would spend billions designing nuke plants
>but fail to squeeze even a single extra HP out of the plant.
How about cutting manning requirements, reducing volume needed, reducing
through life cost, lowering purchase price, and all that good stuff?
Maybe they were more important than doubling horsepower output?
If the installed shp really is up past half a million, it can't have
been cheap to do. CVNs don't use that speed often enough, if they have
it, for there to be anything other than anectotal evidence of it: sounds
like someone got a raw deal...
>Yet most
>everyone here seems to be merrily going along with that assumption. Don't
>you think the designers might be competent enough to improve the plant
>just a bit in 50 years?
How much is "just a bit"? Getting 40+ knots from a Nimitz demands that
the plant _double_ its output, plus the drivetrain needs to be designed
to take that power: everything from the reduction gearing to the
driveshafts to the props has to be sized to handle that power.
To what particular benefit? So you can outrun your escorts? And all that
space and weight is displacing ordnance, aviation fuel, food, and other
useful material that could be placed in there.
--
There are four kinds of homicide: felonious, excusable, justifiable and
praiseworthy...
Paul J. Adam pa...@jrwlynch.demon.co.uk
Bloody Viking
LCDR1635 (lcdr...@aol.com) wrote:
: While flight ops are still normally into the wind, I recall at least one
: occasion when I was onboard NIMITZ (86-88) where we did downwind recoveries.
: Weather upwind was closing to near 0-0 conditions so we turned downwind and
: pushed the speed up enough to get 20kts over the deck, and recovered.
Thanks. I bet they floored it to get that 22mph airspeed driving downwind.
I was making the point that it's not mandatory to turn into the wind and
floor it anymore, like it was in WW 2.0. :)
--
CAUTION: Email Spam Killer in use. Leave this line in your reply! 152680
"A man's car is his battleship"(tm)
2369017 bytes of spam mail deleted. http://www.wwa.com/~nospam/
Thomas A. Beckley
>So who is the liar on Seawolf? Is the Navy a liar when they say she broke
>the previous underwater speed record (44.7 knots)? Or is that 44.7 knot
>record a lie?
>
I was at a presentation by someone who was on the Alpha Trials for Seawolf,
and he said that they "were doing significantly greater than 35 knots with
plenty of horsepower to spare."
I was actually just reading an article earlier today that mentioned the Papa
class's still standing record of 44.7 knots and thought to myself that the
Seawolf could probably break that, and maybe has, but that the Navy would
probably not admit to it.
Andrew Toppan
Thomas A. Beckley (bec...@sprintmail.com) was seen to write:
> Has the Navy officially said they broke the old speed record?
Yes. After Seawolf finished trials, the Navy made a statement to the
effect that "Seawolf is the fastest submarine ever" - I don't have the
exact quote at hand just now. So SSN 21 must be faster than 44.7 knots,
or somebody lies.
Eugene Griessel
el...@WPI.EDU (Andrew Toppan) wrote:
>Eugene Griessel (eug...@dynagen.co.za) was seen to write:
>> Not necessarily. Larger ships need more horsepower, certainly - but the hull
>> shape also plays a large role as do the propellors. And as Paul so nicely
>> pointed out - one cannot merely keep adding horsepower. There comes a point
>> were an infinite increase in horsepower will not bring an inch more in speed -
>Dammit, I'm quite aware of this, and quite aware that it's not relevant to
>whether a CVN can do 40 knots. By your own statements it is possible to
>reach this speed if enough power is applied.
No - my calculations merely showed the power needed to reach this speed.
Whether a drive train and propellors can deliver them is another question
altogether. Theoretically, by the formula I used, we could apply enough power
and get the Nimitz up to the speed of sound - or light if we felt like it.
The practicalities are however different. Those relate to the effective
translation of the power into usable thrust.
>> So why do we want the carriers to go so much faster then?
>Lemme see...
>So our CVN can make a high speed transit if we must, regardless of escorts.
>So our CVN can spend all day dashing about the ocean keeping the wind over
>the deck while the rest of the battlegroup steams along at a more-or-less
>constant speed and course, and at the end of the day the CVN hasn't been
>left behind. If our CVN needs 30 knots over the deck and the group is
>transiting downwind at 20 knots, the CVN either makes 50 knots in the
>direction of transit, or turns around into the wind for a while, then runs
>to catch up. Either way somewhat more than 30 knots would be nice.
Funny these requirements were never needed before.
>Please note I'm NOT saying CVN's are doing 50, 60 or 70 knots constantly,
>or even for a short time. I'm just saying that something more than 30-34
>knots is not too unreasonable. Hell, if an IOWA can do 35 (admittedly
>under abnormal conditions), a CVN ought to be able to do the same, or
>better.
Lemme see. IOWA is slightly more than half the tonnage with 200 000 horses.
Also has a better beam to length ratio. For it to reach 35 knots it would
need an admiralty coefficient of 317 - far worse than the one I used for the
Nimitz. I used 300 for Nimitz, if you recall. All the numbers click for
IOWA. I see no reason to question a 57000 ton ship with 200 000 horses and a
beam to length ratio of 8.2:1 doing 35 knots. The numbers do not click for
Nimitz, however.
I will gladly agree that Enterprise could do 35 knots. 300 000 shp (as
claimed back in the sixties) 10 000 tons or so lighter than a Nimitz but with
a longer hull. I would not be surprised is Enterprise could actually boil up
a knot or so above 35 knots (or could in her heyday).
>> thought the absurdity would become obvious - I also did not take part in the
>> ever-speedier Seawolf discussions for the same reasons. As to people claiming
>So who is the liar on Seawolf? Is the Navy a liar when they say she broke
>the previous underwater speed record (44.7 knots)? Or is that 44.7 knot
>record a lie?
No - but if you recall that discussion we had the usual claims of 60 knots, 70
knots and even higher speeds. One breathless poster even claimed an
unprecedented 87 knots IIRC. If you also remember we had the standard "that
is what the navy admits to - it can actually go a lot faster ...." claims.
Getting a submarine up to high speeds is actually easier than getting a
surface vessel up those same speeds. However I have never been involved in
submarine design - in fact it never came up during my training - so I will
refrain from entering that argument as confidently as I will argue the surface
ship one.
>> addressing my questions as to horsepower needed to push this hull to the
>> speeds you are claiming it capable of. My second set of calculations did not
>> rely on any previously published horsepower. You did not challenge them at
>> all?
>It's Saturday, I have no interest in figuring out math. I do enough of
>that during the week.
Good idea! Go out and get pissed instead. That's what weekends are for.
Bloody Viking
Andrew Toppan (el...@WPI.EDU) wrote:
: So our CVN can spend all day dashing about the ocean keeping the wind over
: the deck while the rest of the battlegroup steams along at a more-or-less
: constant speed and course, and at the end of the day the CVN hasn't been
: left behind. If our CVN needs 30 knots over the deck and the group is
: transiting downwind at 20 knots, the CVN either makes 50 knots in the
: direction of transit, or turns around into the wind for a while, then runs
: to catch up. Either way somewhat more than 30 knots would be nice.
A carrier needs only 22mph airspeed, as a previous poster pointed out. If
the battlegroup was going northbound at 10mph and there was a 12mph wind
out of the north, the carrier could slingshot planes off all day long. A
carrier doesn't have to floor it into the wind anymore. Now, if there was
a 10mph north wind and the carrier was driving southbound, it would need
to go 32mph to get that 22mph airspeed. I somehow think that even that low
airspeed isn't even necessary, though useful. It wouldn't surprise me at
all if a carrier could be _parked_ with zero wind and still do flight ops.
A suitable slingshot and length avoids the need for driving into the wind
at full speed.
Bloody Viking
Eugene Griessel (eug...@dynagen.co.za) wrote:
: Jim Kelly <cats...@freewwweb.com> wrote:
: >A former CO in our ship told me that the "Big E" departed
: >Norfolk at night and arrived off Mayport the next morning at
: >0800. This must be a matter of record with deck logs
: >although I have never pursued the matter. Someone may know
: >the facts, the distances involved, I do not, but I am
: >intrigued by the possibilities.
: Distance is around 550 nautical miles. Depending on what "off Mayport"
: meant.
Don't forget that if it's near the winter solstice, the night is longer,
meaning a slower speed is needed to cover the distance. A 13-hour night
and 550 (sea) miles would mean a speed of 550/13 knots. I get the feeling
it's well below 55mph. Also, if "off mayport" means sighting land from the
top floor of the "island", you get to subtract miles. The speed needed is
less than 45mph. (40 knots) I'm assuming winter solstice and takeoff right
at sunset and landfall at 8 AM the next day.
Peter H. Granzeau
On Fri, 17 Apr 1998 21:20:22 GMT, eug...@dynagen.co.za (Eugene
Griessel) wrote:
>Go down into the stokehold and root out your chief. (That's the fellow
>constantly covered in oil and grease who curses even more than a standard
>sailor). Run the figure of 45 knots by him. Scrape him off the deck when
>his paroxysms of laughter have finally come to a halt.
Without my claiming any knowledge on the subject whatsoever, it would
seem to be a waste of money to overdesign any powerplant beyond what
is necessary for a ship to perform her mission. If a carrier needs 33
knots on tap to operate aircraft, I would assume, then, that the
engines (props, shafts, hull form) would be designed to deliver that
much, and maybe a "J" factor or two more, to account for hull fouling
etc. The nuclear plant probably can deliver a lot more steam than
that requires, but you have a hell of a lot of other things that need
power aboard, too, and the ship probably has molto generators, etc.,
to say nothing of catapults, etc.
Jrchilds
Seems to me that the real limitation is not steam generation, but
condensation, what is the limit of the main condenser before loosing
vacuum. I remember a few DD and FF's that could not hold vacuum at top
end, but the boilers still had a ways to go.
Eugene Griessel wrote:
>
> el...@WPI.EDU (Andrew Toppan) wrote:
>
> >I wouldn't doubt those figures. It's hard to imagine that shp in CV/CVN
> >designs has not gone up AT ALL in the 40+ years since FORRESTAL was
> >designed. FORRESTALs were at 260,000-280,000 hp; it's rather hard to
> >believe they couldn't manage to squeeze just a bit more out of a much more
> >modern nuclear plant.
>
> Firstly the turbine for a nuclear ship is of necessity physically a much
> larger device than that running on superheated steam. Rule of thumb in the
> nuclear industry says 3 times larger. Although that was in 1980 - but Nimitz
> was at sea already. Secondly the reactor is larger and heavier than a boiler
> of similar power output. I am talking total size including shielding, heat
> exchangers and pressurisers. Whatever you do you cannot change the amount of
> power needed to push a given hull at a certain speed. Whether that push is
> from nuclear or gas turbine or conventional steam. I have never, in 20 years,
> seen a figure other than 260 000 to 280 000 quoted for these vessels.
> (Although some of the later ones may be higher - I have not kept that good a
> track).
>
> >Further, your contention that 30 is a true top speed contradicts numerous
> >reports by "pepole who were there" of CVs doing considerably higher
> >speeds. Were they all liars?
>
> Where pray tell did I quote 30 as a true top speed? Please show me? I can
> recall using 34 knots in my calculation. That is the speed most reference
> works give. And it is a reasonable speed for that power and hull.
>
> How did the "people who were there" figure out the speed? How does anyone
> tell the speed of a ship? Measured mile is the only truly accurate figure.
> Don't quote the log at me - those thing have large errors when it comes to
> instaneous readings. Logs are only useful for speed measurement over a
> distance. And I have shared ships with excited seamen who have claimed speeds
> that I know we were incapable of if I had the entire engine room staff eating
> beans and facing backwards. Yes - I will call anyone who tells me Nimitz
> could do a true 40 knots a liar. And I have a very good reason for that.
>
> >And it's reliably known that the FORRESTALs could do just over 30 on
> >280,000 hp. If the NIMITZs were running at that HP rating, I'm quite sure
> >they couldn't even make 30 knots - a patently absurd idea.
>
> I'm not sure I follow your reasoning here Andrew. The Forrestal class have
> always had a published top speed of 34 knots except for Forrestal herself
> which was 33 knots. I imagine these were obtained in standard conditions over
> the measured mile. Forrestal had different machinery to her sisters and was
> 20 000 hp less than the rest of her class. The Kitty Hawk class also had a
> published figure of 280000 shp and a speed of 33 knots. The Enterprise had
> much the same figures.
>
> And so do the Nimitz class.
>
> So point me to any sources that differ on shp for the Nimitz class.
>
> Eugene L Griessel eug...@dynagen.co.za
>
> www.dynagen.co.za/eugene
> SAAF Crashboat Page - www.dynagen.co.za/eugene/eug3.htm
>
> Thought for the day .......
>
> I have a great faith in fools; self-confidence my friends call it.
--
Jack Childs
jrch...@pil.net
"A nation which despises its soldiers will all too soon
have a despicable army
--Jerry Pournelle
Windows-95 is a 32 bit extension and graphical shell for a 16 bit
patch to an 8 bit operating system originally coded for a 4 bit
microprocessor, written by a 2 bit company, that can't stand 1 bit of
competition.
Patrick Pemberton
Bloody Viking wrote in message
>
>Thanks. I bet they floored it to get that 22mph airspeed driving downwind.
>I was making the point that it's not mandatory to turn into the wind and
>floor it anymore, like it was in WW 2.0. :)
You missed what he said. _Near_ 0-0 wind = zero velocity. And ships still
turn into the wind most of the time - wind problems on a mo-board, anyone?
Each naval aircraft type has a chart on a maneuvering board showing the
necessary wind conditions (relative wind speed and direction) for them to be
brought aboard safely. Usually all it takes is a course change rather than
any engine orders.
Visit the USS Texas website at
http://www.ece.utexas.edu/~pemberto
John Weiss
Seldom does a Navy ship go across an ocean alone and at full speed. First,
they are seldom alone (though submarines are often alone, full speed
eliminates their main defense -- quiet). Second, they were not built for
the Guinness Book -- they were built for other purposes. I suppose if you
wanted to invest the money to pay for such a dedicated run, you might be
able to get some government official to allow it. You'd probably wince at
the total cost per mile, though...
---------------------
John R. Weiss
Seattle, WA
Remove *NOSPAM* from address for e-mail reply
Eugene Griessel wrote in message <3537e...@hawk.pix.za>...
>I notice also that nobody has claimed to have beaten the trans-Pacific
record
>that has stood since 1972 which was done at an average speed of 33.27
knots.
>The US Military has never been shy of claiming records - even the then
highly
>secret SR-71 was claiming published and ratified records way back in the
60's
>and early seventies. Why then is the USN so shy of claiming speed records
>with the Nimitz and her sisters?
Dave Welsh
Krztalizer wrote in message
<199804180443...@ladder01.news.aol.com>...
>>
>>Vessels travelling above "hull speed" have to plane in some manner or be
>>submerged, neither of which applies to a CVN.
(snip)
>NOW, you're talking! See, the reason I asked this question is that we were
>spotted during our under-Africa transit by the US tin can USS Hull. Guys
from
>that ship reported that we (Nimitz-twin USS Eisenhower) were dug in on the
>stern, and our bow was coming out of the water from wave to wave. The is a
>photograph of us passing, and at the moment of the shutter, we are going
from
>crest to crest on the waves, with ALL of the bow clear. Now, what kind of
>speed does THAT take?
>
>Plus, anyone serving on a Nimitz-class will agree that when all four screws
get
>cranking (a rare event), the stern digs down as much as 10 feet lower in
the
>water. During low speed transits, the stern deck is dry -- at much higher
>speeds, froth and splash drench anyone trying to fish from the fantail
(another
>rare event, but one our Skipper loved to do).
Planing so as to be able to make 55 knots would probably require the bow to
be out of the water for 1/3 to 1/2 the length of the ship.
I have no idea what the power required to achieve that would be, other than
enormous, but here are some other probable consequences:
1) The hull is subjected to a tremendous bending moment which would easily
break
the keel of any WWII battleship or carrier;
2) The stern would probably be at or below sea level;
3) The ship would be throwing a "rooster tail" maybe 100 feet high.
The "squatting down" behavior you described is exactly what would be
expected when
a ship with that hull form tries to travel above its hull speed. Because the
Nimitz class
has a squared off stern, hydrodynamically it acts like a longer ship,
reducing its wave
making resistance.
But from a static perspective, it still has to be supported by the water.
As the 2nd bow wave moves along the ship until it reaches the stern (which
occurs at
hull speed), the ship is sitting in a moving "hole in the water" which is
deepest amidships
and curves up to sea level at bow and stern. This is the wave caused by the
motion of
the ship, whose creation is now absorbing more power than skin friction. As
the ship's
speed increases beyond that point, the "hole in the water" caused by its
movement
becomes longer than the ship. Its stern settles into the hole and the bow
tilts up. If
speed continues to increase, eventually the ship will start to plane.
From your description I would guess that you were doing no more than 42 to
44 knots.
That is still pretty spectacular performance.
Dave Welsh
dwe...@deltanet.com
Matt Clonfero
Tom <zub...@shore.net> wrote:
>They would be built in the 40 to 60 ton range
Small ships.
Aetherem Vincere
Matt.
--
Matt Clonfero: Mat...@aetherem.demon.co.uk | To Err is Human
My employers and I have a deal - They don't | To forgive is not Air Force Policy
speak for me, and I don't speak for them. | -- Anon, ETPS
Brad Meyer
In message <35375E...@usa.nospam.net> - Brian Varine <Witch*D...@usa.nospam.n
et> writes:
>
>Steve Atkatz wrote:
>>
>> On 17 Apr 1998 08:49:23 GMT, krzta...@aol.com (Krztalizer) fumbled
>> with the keyboard & wrote:
>>
>> >Anyone know how fast a Nimitz can go at full speed on all four screws?
>>
>
>A CVN could whip the SSN chasing it. It's been stated many times that
>the Nuke carriers were designed to outrun any torpedo in the world
>(granted they were designed a while back but still).
If they were, they were misdesigned. I was precom engineering of the
Eisenhower and stood watches during sea trials. I also, earlier in my career,
rode the Scamp during a post yard trial. Ike couldn't outrun the Scamp, much
less one of her torpedos.
Brad Meyer
"It is history that teaches us to hope."
-- R E Lee
Brad Meyer
In message <6h84vr$98i$1...@usenet44.supernews.com> - "Thomas A. Beckley" <beckley
@sprintmail.com> writes:
>
(snip)
>
>It is commonly known that nuclear plants can go to maximum power ratings
>that would not be used except under emergency circumstances, such as when
>trying to outrun a torpedo.
I was a nuke for 7years and precom'ed the Eisenhower and such was not known
to me or any ohter nuke on board.
>I doubt that the true maximum speed capability
>has truly been tested of the modern nuclear carriers, because there has been
>no situation where a nuclear carrier's safety was in imminent danger and it
>needed to flee.
No, its because the only way to get the figure you want is by destructive
testing, i.e. what breaks first and when. FWIW reactor power is not the
limiting fact to max speed on those carriers. The trust bearings on the main
shatfs would fail before any primary plant capacities were reached.
Brad Meyer
In message <6h872h$o0a$1...@bigboote.WPI.EDU> - el...@WPI.EDU (Andrew Toppan) writ
es:>> I doubt that she can put out that sort of power. If I calculate the other
>
>I wouldn't doubt those figures. It's hard to imagine that shp in CV/CVN
>designs has not gone up AT ALL in the 40+ years since FORRESTAL was
>designed. FORRESTALs were at 260,000-280,000 hp; it's rather hard to
>believe they couldn't manage to squeeze just a bit more out of a much more
>modern nuclear plant.
You can out of the plant, but the shafting and thrustbearings are no newer in
design. The reactor power is there but you can't apply it to the shafting.
EJ Moncrieff
In article <35395...@news1.ibm.net>, br...@ibm.net says...
And, might I add, a most hearty Amen, brother.
--
"There is in human nature generally more of the fool
than the wise; and therefore those faculties by which
the foolish part of men's minds is taken are most potent."
LCDR1635
>You missed what he said. _Near_ 0-0 wind = zero velocity. And ships
Actually that's not what I meant. I meant that continuing upwind to recover
would have taken us into a weather system that the ceiling and visibility
conditions would have approached 0-0. While I still feel that discussing the
actual speed we had to make heading downwind to get 20 kts over deck would be
getting into classified information, lets just say it was notably over 30kts.
IIRC this occured during airwing (CVW-9) CQs in early 88 (about 3 years after
the most recent drydocking).
John H. Eckhardt
It's not my spelling or grammar that's so bad. It's my typing.
LCDR1635
Other than test speed runs, in two years onboard NIMITZ I only recall three.
One when we and SoCar detached from out battle group and headed around Iceland
to outrun the Krivak that was tattletaling us (actually it didn't take much to
leave him behind, but we did pore on the"neutrons" for a while).
The second time was to get within Helo range of Bermuda to MEDEVAC a sailor who
had been badly burned in a steam leak.
The third was that same dependent's cruise you mentioned in your earlier post.
I also recall making serious turns going around the Horn (don't recall the
actual speed, though) to make the passage between storm fronts (it was June).
As it was we had 70-80kt wind down the deck and lost the NTDS antenna.
Bloody Viking
Patrick Pemberton (patr...@ccwf.cc.utexas.edu) wrote:
: Each naval aircraft type has a chart on a maneuvering board showing the
: necessary wind conditions (relative wind speed and direction) for them to be
: brought aboard safely. Usually all it takes is a course change rather than
: any engine orders.
It's always easier to take off than to land. That's true with ships
themselves and even cars. In the case of a truck, it's easier to "blast
off" then to pull up to a loading dock. In the case of a carrier, you just
simply drive into the wind.
I recognise "speed over the deck" as "airspeed" like I do with cars. An
aircraft carrier driving northbound into a wind from the north will have a
40mph wind "on the deck" if wind is 20mph and the ship is doing 20mph.
That's the airspeed of the vehicle/vessel.
Guy Derdall
God!!
Now the Iowa's can do 35 knots, a few months ago they couldn't no way no
how. Man make up your minds.
If you really want to know something about the Iowa's hull design is that it
is not an altogether efficent hull form.
The Nimitz's hulls are actually a more standard hull form that was found
after the Iowa's were built to be better for high speeds.
The Iowa's get their high speeds from massive horsepower not hull form.
One gent e-mailed me with a little story I will put here. Take it as a sea
story or whatever you may. I don't know if it's true or what.
On the way to the Persian Gulf, this gent was on one of the Nimitz's ( can't
remember which one sorry)
On the crew television they had a speed indicator at the bottom of the
screen (Is this true anyone?) it was saying 40 knots, then went "classified"
and the ship was still picking up speed.
But almost every book you can see and every carrier sailor says 30+ with 40
knots easy.
--
*****************************************************
Guy Derdall
Battleships Carriers And All Other Warships
http://warships.4biz.net/index2.htm
"The Anchor Page For The World's Warships"
*****************************************************
e-mail battl...@sk.sympatico.ca
*****************************************************
Eugene Griessel wrote in message <35392...@hawk.pix.za>...
>el...@WPI.EDU (Andrew Toppan) wrote:
>
>>Eugene Griessel (eug...@dynagen.co.za) was seen to write:
>
>>> Not necessarily. Larger ships need more horsepower, certainly - but the
hull
>>> shape also plays a large role as do the propellors. And as Paul so
nicely
>>> pointed out - one cannot merely keep adding horsepower. There comes a
point
>>> were an infinite increase in horsepower will not bring an inch more in
speed -
>
>>Dammit, I'm quite aware of this, and quite aware that it's not relevant to
>>whether a CVN can do 40 knots. By your own statements it is possible to
>>reach this speed if enough power is applied.
>
>No - my calculations merely showed the power needed to reach this speed.
>Whether a drive train and propellors can deliver them is another question
>altogether. Theoretically, by the formula I used, we could apply enough
power
>and get the Nimitz up to the speed of sound - or light if we felt like it.
>The practicalities are however different. Those relate to the effective
>translation of the power into usable thrust.
>
>>> So why do we want the carriers to go so much faster then?
>
>>Lemme see...
>
>>So our CVN can make a high speed transit if we must, regardless of
escorts.
>
>>So our CVN can spend all day dashing about the ocean keeping the wind over
>>the deck while the rest of the battlegroup steams along at a more-or-less
>>constant speed and course, and at the end of the day the CVN hasn't been
>>left behind. If our CVN needs 30 knots over the deck and the group is
>>transiting downwind at 20 knots, the CVN either makes 50 knots in the
>>direction of transit, or turns around into the wind for a while, then runs
>>to catch up. Either way somewhat more than 30 knots would be nice.
>
>Funny these requirements were never needed before.
>
>>Please note I'm NOT saying CVN's are doing 50, 60 or 70 knots constantly,
>>or even for a short time. I'm just saying that something more than 30-34
>>knots is not too unreasonable. Hell, if an IOWA can do 35 (admittedly
>>under abnormal conditions), a CVN ought to be able to do the same, or
>>better.
>
>Lemme see. IOWA is slightly more than half the tonnage with 200 000 horses.
>Also has a better beam to length ratio. For it to reach 35 knots it would
>need an admiralty coefficient of 317 - far worse than the one I used for
the
>Nimitz. I used 300 for Nimitz, if you recall. All the numbers click for
>IOWA. I see no reason to question a 57000 ton ship with 200 000 horses and
a
>beam to length ratio of 8.2:1 doing 35 knots. The numbers do not click for
>Nimitz, however.
>
>I will gladly agree that Enterprise could do 35 knots. 300 000 shp (as
>claimed back in the sixties) 10 000 tons or so lighter than a Nimitz but
with
>a longer hull. I would not be surprised is Enterprise could actually boil
up
>a knot or so above 35 knots (or could in her heyday).
>
>>> thought the absurdity would become obvious - I also did not take part in
the
>>> ever-speedier Seawolf discussions for the same reasons. As to people
claiming
>
>>So who is the liar on Seawolf? Is the Navy a liar when they say she broke
>>the previous underwater speed record (44.7 knots)? Or is that 44.7 knot
>>record a lie?
>
>No - but if you recall that discussion we had the usual claims of 60 knots,
70
>knots and even higher speeds. One breathless poster even claimed an
>unprecedented 87 knots IIRC. If you also remember we had the standard
"that
>is what the navy admits to - it can actually go a lot faster ...." claims.
>
>Getting a submarine up to high speeds is actually easier than getting a
>surface vessel up those same speeds. However I have never been involved in
>submarine design - in fact it never came up during my training - so I will
>refrain from entering that argument as confidently as I will argue the
surface
>ship one.
>
>>> addressing my questions as to horsepower needed to push this hull to the
>>> speeds you are claiming it capable of. My second set of calculations
did not
>>> rely on any previously published horsepower. You did not challenge them
at
>>> all?
>
>>It's Saturday, I have no interest in figuring out math. I do enough of
>>that during the week.
>
>Good idea! Go out and get pissed instead. That's what weekends are for.
>
Eugene Griessel
"Guy Derdall" <battl...@sk.sympatico.ca> wrote:
>God!!
>Now the Iowa's can do 35 knots, a few months ago they couldn't no way no
>how. Man make up your minds.
The difference between physical possibility and reality still seems to elude
you.
>If you really want to know something about the Iowa's hull design is that it
>is not an altogether efficent hull form.
>The Nimitz's hulls are actually a more standard hull form that was found
>after the Iowa's were built to be better for high speeds.
>The Iowa's get their high speeds from massive horsepower not hull form.
>One gent e-mailed me with a little story I will put here. Take it as a sea
>story or whatever you may. I don't know if it's true or what.
>On the way to the Persian Gulf, this gent was on one of the Nimitz's ( can't
>remember which one sorry)
>On the crew television they had a speed indicator at the bottom of the
>screen (Is this true anyone?) it was saying 40 knots, then went "classified"
>and the ship was still picking up speed.
Was this before or after they picked up mail from the Flying Dutchman? Or
maybe the sea serpent was chasing them. Or even more likely what most of them
are measuring is wind over the deck speed.
>But almost every book you can see and every carrier sailor says 30+ with 40
>knots easy.
What every carrier sailor seems to lack is a basic knowledge of naval
architecture and powering. It is very special pleading to imagine a 34 knot
ship can go "40 knots" easy. As one other poster here pointed out the thrust
blocks would not stand for it - just as starters.
Guy Derdall
Eugene Griessel wrote in message <3539b...@hawk.pix.za>...
>"Guy Derdall" <battl...@sk.sympatico.ca> wrote:
>
>>God!!
>>Now the Iowa's can do 35 knots, a few months ago they couldn't no way no
>>how. Man make up your minds.
>
elude
>you.
??? You said it was conceivable that the Iowa's could go 35 knots.
Changing your tune now perhaps?
>
>>If you really want to know something about the Iowa's hull design is that
it
>>is not an altogether efficent hull form.
>>The Nimitz's hulls are actually a more standard hull form that was found
>>after the Iowa's were built to be better for high speeds.
>>The Iowa's get their high speeds from massive horsepower not hull form.
>>One gent e-mailed me with a little story I will put here. Take it as a sea
>>story or whatever you may. I don't know if it's true or what.
>>On the way to the Persian Gulf, this gent was on one of the Nimitz's
can't
>>remember which one sorry)
>>On the crew television they had a speed indicator at the bottom of the
>>screen (Is this true anyone?) it was saying 40 knots, then went
"classified"
>>and the ship was still picking up speed.
>
>Was this before or after they picked up mail from the Flying Dutchman? Or
>maybe the sea serpent was chasing them. Or even more likely what most of
them
>are measuring is wind over the deck speed.
>
I have no idea, but you know as much as me.
>>But almost every book you can see and every carrier sailor says 30+ with
40
>>knots easy.
>
>What every carrier sailor seems to lack is a basic knowledge of naval
>architecture and powering. It is very special pleading to imagine a 34
knot
>ship can go "40 knots" easy. As one other poster here pointed out the
thrust
>blocks would not stand for it - just as starters.
>
>
Of course, that's it, the sailors on board the ships have no understanding
of a ships speed, they have never asked the captain"say Cap how fast are we
going?" They have never asked the engineers or bridge crew, "how fast can
this thing really go?"
They just make up stories like this, so we can have something to argue about
on SMN.
Are you sure that all the propulsion system behind the turbines are the same
in the Forrestals as they are in the Nimitz's? I find this hard to believe.
Any "real" engineers here? Or builder's?