Nimitz carrier doing a hard turn

Ender · Post by **Ender** » 2003-02-01 10:38pm

Ted wrote:Pure hull form will limit the carriers top speed.

There is no way the ship can do 45kts.

And yet they do, and faster. Funny that.

Frank Hipper · Post by **Frank Hipper** » 2003-02-01 10:38pm

Ted wrote:Pure hull form will limit the carriers top speed.

There is no way the ship can do 45kts.

How so? Propellor design would be a larger factor here. With their bulbous forefoot and fine lines, modern carriers have an admirable lack of underwater drag.

Ender · Post by **Ender** » 2003-02-01 10:39pm

phongn wrote:
Frank Hipper wrote:Although top speed's classified, I've heard that Enterprise could do 45kts, I wouldn't be suprised if Nimitz is doing 35-40 in that photo. I've got a book with a photo of a WWI British "R"class battleship doing a "helm hard over" manouver like that. But at one third the displacement, roughly 5/8 the length, and half the speed, it just doesn't compare.
No. Top speed of the US carriers top out around 30-33 kts depending one which on you're talking about.

Post your source, since every 1st class and Chief here give the official line of "over 45 knots", and frankly, since I have no idea what your experience level is, I'm inclinded to take their word over yours.

Ted · Post by **Ted** » 2003-02-01 10:42pm

Ender wrote:
phongn wrote:
Frank Hipper wrote:Although top speed's classified, I've heard that Enterprise could do 45kts, I wouldn't be suprised if Nimitz is doing 35-40 in that photo. I've got a book with a photo of a WWI British "R"class battleship doing a "helm hard over" manouver like that. But at one third the displacement, roughly 5/8 the length, and half the speed, it just doesn't compare.
No. Top speed of the US carriers top out around 30-33 kts depending one which on you're talking about.
Post your source, since every 1st class and Chief here give the official line of "over 45 knots", and frankly, since I have no idea what your experience level is, I'm inclinded to take their word over yours.

It is NOT official.

The OFFICIAL is 30kts +

Yours is heresay.

Ender · Post by **Ender** » 2003-02-01 10:44pm

phongn wrote:
Alyeska wrote:I find it interesting how many people not in the military say nothing more then 35 knots. Yet I have heard from multiple saliors now that the Nimitz class can hit the mid 40s.
I find it highly unlikely, still - they may be overexaggerating.

The official line on them is "90,000 tons of diplomacy at over 45 knots: Join the Nuclear Navy", and I have been told by every instructor that it is greater then 45, and Evans (a guy in my class) worked out 53 knots based on comparing the horsepower of the turbines on the Lexington to those on the Enterprise (though that is highly suspect and involved more assumptions then Crossover Maniac's calcs.)

Ender · Post by **Ender** » 2003-02-01 10:46pm

Ted wrote: It is NOT official.

The OFFICIAL is 30kts +

Yours is heresay.

*reads poster on the wall of his room*
"90,000 tons of diplomacy at over 45 knots: Join the Nuclear Navy"
*looks at corner*
"USN"

Post your source.

Ted · Post by **Ted** » 2003-02-01 10:50pm

Ender wrote:Post your source.

http://www.chinfo.navy.mil/navpalib/fac ... ip-cv.html

Speed: 30+ knots (34.5+ miles per hour)

Ender · Post by **Ender** » 2003-02-01 10:52pm

Alright then, contradictory sources. What now?

Ted · Post by **Ted** » 2003-02-01 10:55pm

Ender wrote:Alright then, contradictory sources. What now?

Poster is government propoganda used to get more into the navy, most likely gross exageration.

Max speed is most likely 35kts, definately not 45kts.

The Dark · Post by **The Dark** » 2003-02-01 11:00pm

the USN publicly released the speed of the nuclear carriers in June 1999:
Enterprise 33.6 knots after last refit
Nimitz 31.5 knots
Theodore Roosevelt 31.3 knots
Harry S Truman 30.9 knots

Of course, we all know how accurate official government figures are...I would say this is what they'll admit to, not necessarily what is real. However, given that they have only 280,000 horsepower, I would say closer to 35 than 45, and probably closer to 35 than 40. I may need to chat with a few friends who gave me propaganda rather than reality...

phongn · Post by **phongn** » 2003-02-01 11:20pm

warships1.com has a good article on this:

http://www.warships1.com/W-Tech/tech-028.htm

Post by **Sea Skimmer** » 2003-02-01 11:31pm

Anything over 40 knots is a load of total shit. Even destroyers with a light fuel load have a hard time reaching that speed; even WW2 jobs generally can't pass 36 if that, and no significant sized warship has ever past 42. There's no way in hell a Nimitz could even approach it with its hull form, and it doesn't matter how much power the thing can put into the shafts.

Anything over 35 is unlikely to be true either. Once again that's straining it for ships far better designed for speed. Speeds more then a two or three knots higher then the published figures really are impossible.

Post by **Sea Skimmer** » 2003-02-01 11:39pm

Ender wrote:
phongn wrote:
Alyeska wrote:I find it interesting how many people not in the military say nothing more then 35 knots. Yet I have heard from multiple saliors now that the Nimitz class can hit the mid 40s.
I find it highly unlikely, still - they may be overexaggerating.
The official line on them is "90,000 tons of diplomacy at over 45 knots: Join the Nuclear Navy", and I have been told by every instructor that it is greater then 45, and Evans (a guy in my class) worked out 53 knots based on comparing the horsepower of the turbines on the Lexington to those on the Enterprise (though that is highly suspect and involved more assumptions then Crossover Maniac's calcs.)

Load of shit. It's impossible for any conventional ship to reach those speeds, you cant just keep dumping HP into the shafts to go faster, you end up with heavy cavitations and becoming less and less efficient until the screws are no longer moving the ship at all.

How the fuck you could make a comparision of horsepower betwen those two ships and come out with 53 knots I dont know. Mabey by ignoring displacement and showing a total ignorance of the differing hull forms. You'd also need to have minimal if any knowledge of shaft loading limitations and think you could just keep adding power.

The Dark · Post by **The Dark** » 2003-02-02 12:23am

phongn wrote:warships1.com has a good article on this:

http://www.warships1.com/W-Tech/tech-028.htm

That was the article I quoted right above your post, but I lost the link before I could write where it was from (comp crashed).

Marcus · Post by **Marcus** » 2003-02-02 01:13am

I do not know of my own knowledge anything on this topic.

I have told by various people in the naval service that "If its top speed was 33 Knots, we'd by-god tell people it was 25. This is the Military."

Then again, I suppose its axiomatic that..
1.) Sailors like telling Sea-Stories and/or
2.) The Military likes creating FUD about its capabilities.

Hyperion · Post by **Hyperion** » 2003-02-02 03:16am

I had a friend on the Carl Vinson, a nuke tech, he knew the engines and what the ship could do, he did tell me that if they go for a "one-way ride" with everything at redline that the ship can do at least double or more the publicised speed, though he could not tell me precisely.

Tsyroc · Post by **Tsyroc** » 2003-02-02 12:51pm

Hyperion wrote:I had a friend on the Carl Vinson, a nuke tech, he knew the engines and what the ship could do, he did tell me that if they go for a "one-way ride" with everything at redline that the ship can do at least double or more the publicised speed, though he could not tell me precisely.

That seems theoretically feesible to me. If the posted top end is 33-35knots then redlining at 66-70 doesn't sound too far fetched. I've served on a Nimitz class carrier and I know they can go faster than posted because I've seen quite a bit of evidence for it. The main one is a computerized chart that displays the ships course. When you click on segments it will tell you how fast the ship must have been going to cover that distance in the amount of time it did. Some do seem a bit extreme but plenty of them are at least 35 knots.

The Navy does make some efforts to conceal the top speed. The ACDS system that nearly everyone in CDC uses to monitor radars won't display the ship's speed beyond the posted max. It just sits there pegging at the max. The cool thing is that you can click on other ships/planes on your screen and see how fast they are going. I heard from one of our escort cruisers that they had us doing 55 knots one time.

By the way, as for some of the escort ships I always heard that the limting factor for the Ticonderoga and Spruance ships is the sonar dome. Without it they are supposed to be able to do at least in the high 40 knot range but with it they can damage it if they go all out.

Post by **Sea Skimmer** » 2003-02-02 01:02pm

Tsyroc wrote:
Hyperion wrote:I had a friend on the Carl Vinson, a nuke tech, he knew the engines and what the ship could do, he did tell me that if they go for a "one-way ride" with everything at redline that the ship can do at least double or more the publicised speed, though he could not tell me precisely.

That seems theoretically feesible to me. If the posted top end is 33-35knots then redlining at 66-70 doesn't sound too far fetched. I've served on a Nimitz class carrier and I know they can go faster than posted because I've seen quite a bit of evidence for it. The main one is a computerized chart that displays the ships course. When you click on segments it will tell you how fast the ship must have been going to cover that distance in the amount of time it did. Some do seem a bit extreme but plenty of them are at least 35 knots.

The Navy does make some efforts to conceal the top speed. The ACDS system that nearly everyone in CDC uses to monitor radars won't display the ship's speed beyond the posted max. It just sits there pegging at the max. The cool thing is that you can click on other ships/planes on your screen and see how fast they are going. I heard from one of our escort cruisers that they had us doing 55 knots one time.

By the way, as for some of the escort ships I always heard that the limting factor for the Ticonderoga and Spruance ships is the sonar dome. Without it they are supposed to be able to do at least in the high 40 knot range but with it they can damage it if they go all out.

Its not. Running ever more power through a shaft and propeller won't give you more speed. It will give you less after a point as a propeller becomes less efficient the faster its spins and will eventually begin cavitating. At that point the propeller is churning through a bubble and not moving any water. The ship will then rapidly come to a halt. For various reasons, you can't utilize more then about 80,000 hp through a single shaft. More then that will just be wasted in massive inefficiencies. That of course assumes your turbines can take it.

Small guided missile armed hydrofoils can barely reach 70 knots. A mono hulled surface warship over 100 tons has never reached even 45 knots. Even the Italians with cruisers built purely for speed, running trials with minimal fuel, no guns or turrets, minimal installed armor and reduced stores could only get up into the mid to high 30's.

Read these, then decide if you want to belive hyperbole about speeds, which have never been achieved by anything but hydrofoils

http://www.warships1.com/W-Tech/tech-001.htm
http://www.warships1.com/W-Tech/tech-034.htm
http://www.warships1.com/W-Tech/tech-036.htm

Post by **Sea Skimmer** » 2003-02-02 01:08pm

Ender wrote:
Ted wrote:Pure hull form will limit the carriers top speed.

There is no way the ship can do 45kts.
And yet they do, and faster. Funny that.

When? Hell, name one significant warship ever that could reach 45 knots without using hydrofoils.

Tsyroc · Post by **Tsyroc** » 2003-02-02 01:09pm

The Dark wrote:
phongn wrote:warships1.com has a good article on this:

http://www.warships1.com/W-Tech/tech-028.htm
That was the article I quoted right above your post, but I lost the link before I could write where it was from (comp crashed).

After looking at the article I would say that his information is pretty close to accurate for the Forestal class. I think the Saratoga seemed to pretty much top out around 33ish for the most part while I was on her. I wouldn't argue with anyone if they said the top end was 32 that's for sure. I do know that she accelerated pretty well because we smoked the shit ouf of a little Greenpeace speed boat.

Also, the Enterprise in the past was supposed to be the fastest carrier mainly becuase it was designed more like a regular ship, with a more prominent keel than the Nimitz class which are pretty flat in the back. It the E is still the fastest since it's big overhaul I don't know.

One thing I always heard mentioned as a reason why carriers were limited to the posted speeds was because of the screw design and not the amount of power. Supposedly when first commissioned the Enterprise could really hall ass but it's acceleration wasn't that good. So, supposedly she was refited with screws with a different pitch that would allow her to accelerate more quickly and aid in dodging things. Besides, having a high top end is pretty much useless if your escorts (cruisers, subs) can't keep up. No point in getting somewhere only to be spanked because you left your protection behind.

I have never heard anyone say that the speed on a Nimitz was limited because of power. I have had engineering personel tell me they could apply more power to the shaft than the ship could really handle. It would risk damaging the shaft and after a certain point you get diminishing returns, possibly even slowing the ship even though the screws are going faster (once again I think this is a limitation based on the pitch of the blades but I'm not certain).

Post by **Sea Skimmer** » 2003-02-02 01:10pm

Ender wrote:
Ted wrote: It is NOT official.

The OFFICIAL is 30kts +

Yours is heresay.
*reads poster on the wall of his room*
"90,000 tons of diplomacy at over 45 knots: Join the Nuclear Navy"
*looks at corner*
"USN"

Post your source.

So a recruitment poster is your source? Recruiters lie directly to peoples faces, and your using a poster as your source? When the publish figures and everything else say otherwise?

Right...

Post by **Sea Skimmer** » 2003-02-02 01:15pm

Tsyroc wrote:
The Dark wrote:
phongn wrote:warships1.com has a good article on this:

http://www.warships1.com/W-Tech/tech-028.htm
That was the article I quoted right above your post, but I lost the link before I could write where it was from (comp crashed).
After looking at the article I would say that his information is pretty close to accurate for the Forestal class. I think the Saratoga seemed to pretty much top out around 33ish for the most part while I was on her. I wouldn't argue with anyone if they said the top end was 32 that's for sure. I do know that she accelerated pretty well because we smoked the shit ouf of a little Greenpeace speed boat.

Also, the Enterprise in the past was supposed to be the fastest carrier mainly becuase it was designed more like a regular ship, with a more prominent keel than the Nimitz class which are pretty flat in the back. It the E is still the fastest since it's big overhaul I don't know.

One thing I always heard mentioned as a reason why carriers were limited to the posted speeds was because of the screw design and not the amount of power. Supposedly when first commissioned the Enterprise could really hall ass but it's acceleration wasn't that good. So, supposedly she was refited with screws with a different pitch that would allow her to accelerate more quickly and aid in dodging things. Besides, having a high top end is pretty much useless if your escorts (cruisers, subs) can't keep up. No point in getting somewhere only to be spanked because you left your protection behind.

I have never heard anyone say that the speed on a Nimitz was limited because of power. I have had engineering personel tell me they could apply more power to the shaft than the ship could really handle. It would risk damaging the shaft and after a certain point you get diminishing returns, possibly even slowing the ship even though the screws are going faster (once again I think this is a limitation based on the pitch of the blades but I'm not certain).

That's part of it. Its also limited by shear propeller size as well. The bigger the prop is the slower it can spin on the same power. The slower you spin the more efficient you are and further away you remain from heavy cavitations which makes the thing useless.

Tsyroc · Post by **Tsyroc** » 2003-02-02 01:17pm

Sea Skimmer wrote: Its not. Running ever more power through a shaft and propeller won't give you more speed. It will give you less after a point as a propeller becomes less efficient the faster its spins and will eventually begin cavitating. At that point the propeller is churning through a bubble and not moving any water. The ship will then rapidly come to a halt. For various reasons, you can't utilize more then about 80,000 hp through a single shaft. More then that will just be wasted in massive inefficiencies. That of course assumes your turbines can take it.

Small guided missile armed hydrofoils can barely reach 70 knots. A mono hulled surface warship over 100 tons has never reached even 45 knots. Even the Italians with cruisers built purely for speed, running trials with minimal fuel, no guns or turrets, minimal installed armor and reduced stores could only get up into the mid to high 30's.

Read these, then decide if you want to belive hyperbole about speeds, which have never been achieved by anything but hydrofoils

http://www.warships1.com/W-Tech/tech-001.htm
http://www.warships1.com/W-Tech/tech-034.htm
http://www.warships1.com/W-Tech/tech-036.htm

It's not hyperbole if you've seen it.

Now what I have seen might not be the whole picture. Certainly I don't know the accuracy of the systems I was mentioning as sources. There's also the possibility of misinterpretation on my part.

As for the hydrofoils, the USN's PHMs were still active when I was stationed in Florida and I've talked to people who say they clocked them doing over 100knots. Talk about hyperbole.

Seems a bit much if they are supposed to top out at 48knots, which is still damn fast on the water.

Post by **Sea Skimmer** » 2003-02-02 01:29pm

Tsyroc wrote:
Sea Skimmer wrote: Its not. Running ever more power through a shaft and propeller won't give you more speed. It will give you less after a point as a propeller becomes less efficient the faster its spins and will eventually begin cavitating. At that point the propeller is churning through a bubble and not moving any water. The ship will then rapidly come to a halt. For various reasons, you can't utilize more then about 80,000 hp through a single shaft. More then that will just be wasted in massive inefficiencies. That of course assumes your turbines can take it.

Small guided missile armed hydrofoils can barely reach 70 knots. A mono hulled surface warship over 100 tons has never reached even 45 knots. Even the Italians with cruisers built purely for speed, running trials with minimal fuel, no guns or turrets, minimal installed armor and reduced stores could only get up into the mid to high 30's.

Read these, then decide if you want to belive hyperbole about speeds, which have never been achieved by anything but hydrofoils

http://www.warships1.com/W-Tech/tech-001.htm
http://www.warships1.com/W-Tech/tech-034.htm
http://www.warships1.com/W-Tech/tech-036.htm
It's not hyperbole if you've seen it. Now what I have seen might not be the whole picture. Certainly I don't know the accuracy of the systems I was mentioning as sources. There's also the possibility of misinterpretation on my part.

As for the hydrofoils, the USN's PHMs were still active when I was stationed in Florida and I've talked to people who say they clocked them doing over 100knots. Talk about hyperbole. Seems a bit much if they are supposed to top out at 48knots, which is still damn fast on the water.

Considering the USN found the PHM's a total faliure, I doubt they where twice as fast as a high end torpedo.

As for your method of measuring speed, just what exactly where you using and what speed where you getting? I cant recall if you said so.

Tsyroc · Post by **Tsyroc** » 2003-02-02 01:58pm

Sea Skimmer wrote: Considering the USN found the PHM's a total faliure, I doubt they where twice as fast as a high end torpedo.

As for your method of measuring speed, just what exactly where you using and what speed where you getting? I cant recall if you said so.

Yeah, I didn't think the PHMs where that fast either. From what I heard they were a maintenance nightmare because of the foils and the water jet. I also heard that they only worked well on relatively calm seas. At one time there was supposedly a plan for a ship to carry the PHMs so they could be deployed in places like the Persion Gulf but I've never seen anything other than a sketch.

I can't remember the name of the system I was looking at but it did a lot of things. It had a nice color map display which could be zoomed in and out and the TAO usually had a large projection screen version of it in front of him. On that system what I did was to display a history of our course. The course was broken down into legs. Because the two end points of the legs were documented at specific times this system would give you speed reading based on the time it took to cover the specific distance in the leg.

I didn't say any specific speeds from that system. I just said that I saw a lot that were well over the posted top end of the Nimitz class. I should also say that there were a couple that we so far over that I wasn't buying them which is why I am willing to sugest that what I feel a Nimitz class is capable of may be because I misinterpreted data or don't know the limitations of the system. Heck, I don't know if we were going with the wind, with the current etc... IIRC this system tracked everything by sattelite so it's going to be looking purely at the distance covered and what amount of time.

Still, I feel fairly confident that despite what that article says the Nimtz class is faster than the Forrestal class.