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The_TrashMan

Iowa - incorrect data (speed, dispersion)

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Noticed two mistakes in regards to the Iowa.

 

It's top speed is listed as 31knots, yet every source I've seen (and I've seen a lot. I've got 2400+ books in my house and most of them are about ships) mentions 33 knots (with 35 achieved during tests).

 

Also, the dispersion for it's guns in tests made in 1945 was 220m, not 270m

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Weekend Tester
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Noticed two mistakes in regards to the Iowa.

 

It's top speed is listed as 31knots, yet every source I've seen (and I've seen a lot. I've got 2400+ books in my house and most of them are about ships) mentions 33 knots (with 35 achieved during tests).

 

Also, the dispersion for it's guns in tests made in 1945 was 220m, not 270m

 

It's a video game not an accurate historical simulation.  Iowa is slowed down for balance purpose. Otherwise you will start to add things her naverage to below average side Armor, her bad seakeeping in bad weather and extremely weak and prone to damage bow.  Not even to mention ythat at her top speed 34/35 knot she was subject to unacceptable vibrations causing machinery damage.

 

 

Edited by Harada_Taro

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There are other ships that don't have their historical stats. I guess devs want it that way.

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View PostThe_TrashMan, on 18 May 2015 - 06:33 AM, said:

Noticed two mistakes in regards to the Iowa.

 

It's top speed is listed as 31knots, yet every source I've seen (and I've seen a lot. I've got 2400+ books in my house and most of them are about ships) mentions 33 knots (with 35 achieved during tests).

 

Also, the dispersion for it's guns in tests made in 1945 was 220m, not 270m

 

It's a video game not an accurate historical simulation.  Iowa is slowed down for balance purpose. Otherwise you will start to add things her naverage to below average side Armor, her bad seakeeping in bad weather and extremely weak and prone to damage bow.  Not even to mention ythat at her top speed 34/35 knot she was subject to unacceptable vibrations causing machinery damage.

 

 

That was the New Mexico.. .or was it the New York? I keep confusing those two.

 

I know this isn't 100% accurate because muh balance, but personally, it irks me to see some of the most iconic features removed. Iowa was known for speed and accuracy.

 

Then again, I'm not that much concerned with US-Jap balance to begin with, since teams are mixed from all nations. Some ships simply were better, and Tiers are an artificial construct in the game.

If a ship is very strong for it's tier, it either doesn't belong there, or the MM can compensate by:

a) giving the other team more ships

b) giving the other team the same ship

c) putting you against higher tiers

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Individual MM weights you can forget about in the first place. WG has a policy against that now. Besides, it would cause the statpadders to choose the vessels with lowest MM weight, just so they could be at the top of the tier most of the time.

 

Regarding the missing speed: Is the 35 knots maximum speed or design speed? Because most vessels (even today), can achieve speeds that are above what's listed (maximum operational speed), but it will cause damage to the propellers (increased cavitation, will cause failure over time), hull vibrations, wear on the engines and horrendous fuel consumption. 

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Well this is from someone who served on the Iowa:

 

  It was one of the fastest ships of its size and mass ever built, capable of well over 30 knots; its top speed was long classified, but some have placed it at near 40 knots, or 46mph.

 

So on a perfect case 34-35 knots do not seem to be out of the ordinary.

 

Maximum speed was seldom used on ships as it had a very high fuel consumption, most of the time you would run in cruising speed, that is about 2/3rd of the full speed. Just to visualize how much more fuel is needed to reach that last 1/3. On a ship with 2 turbines you could reach cruising speed by running only one turbine at about full power, to reach the maximum speed you would need to run both at full power. So you need double the engine power to just get an additional 1/3 at max imum of speed.

 

And also from the same about accuracy of the Iowas gunsystem:

 

 “At one time, my office was asked to do a study regarding upgrading the Iowa-class battleship fire control systems from analog to digital computers,” Boslaugh replied. “We found that digitizing the computer would improve neither the reliability nor the accuracy of the system and recommended, ‘Don't bother.’” Even without digital computers, the Iowa could fire 2,700-pound “dumb” shells nearly 30 miles inland with deadly accuracy, within a circle of probable error of around 80 meters. Some of its shells had circles of destruction larger than that.

 

The guy that is quoted here is: Captain David Boslaugh (http://ethw.org/User:davidboslaugh), former director of the Navy Tactical Embedded Computer Program Office.

 

But then we know from World of tanks that Wargaming likes to modify some stats to fit their game and view.

Edited by Boomer7

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Weekend Tester
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  It was one of the fastest ships of its size and mass ever built, capable of well over 30 knots; its top speed was long classified, but some have placed it at near 40 knots, or 46mph.

 

Whoever said that is just a liar....   she has been pushed to her max, encountered vibrations, unacceptable to sustain her max speed for long time and she topped between 34 and 35...

To achieve such a speed 40knots  with her shape, length, beam and weight she would need, different propellers, more than 4 and a global shafthorsepower greater than 350K.  So claiming 40 is just purely [edited].  

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35 was max achieved, but 33 was standard.

Just because you CAN push the Iowa to 35 kn, doesn't mean you should.

 

I still think the value of 31 is too little, the Kongo can match that FFS!

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Guess she was nerfed so that WG have an excuse to put the Montana in... Ooooh, look how bad the Iowa is, it can't possibly face a Yamato, we should get a paper ship to take her place instead.

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Also, the dispersion for it's guns in tests made in 1945 was 220m, not 270m

 

Could you please cite the source for this value?

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Whoever said that is just a liar....   she has been pushed to her max, encountered vibrations, unacceptable to sustain her max speed for long time and she topped between 34 and 35...

To achieve such a speed 40knots  with her shape, length, beam and weight she would need, different propellers, more than 4 and a global shafthorsepower greater than 350K.  So claiming 40 is just purely [edited].  

 

Well as the quote says the sped was far exceeding 30 knots and some said to belief it was close to 40, close to can be anything from 36-39 knots.

And maybe they found a stretch of ocean sloping downwards for the speedtrials :D

 

But the fact remains that obviously the Iowa was capable of doing more then 31 knots.

 

 

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Now let's clear out the confusion here, Iowas top speed was for quite a long time classified and stated as "over 30knot", which have created alot of confusion.

Iowa had a maximum design speed of 32.5 knots, but could in theory cram out 20% higher SHP (Ship horsepower) from the engines without inflicting permanent damage to them which allowed it to reach 35.4 knots according to the models.

The highest credible known speed with an Iowa class Battleship was achieved by USS New Jersey just before deploying to Vietnam and recorded as 35.2 knots.

Source: http://www.navweaps.com/index_tech/tech-029.htm

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Well as the quote says the sped was far exceeding 30 knots and some said to belief it was close to 40, close to can be anything from 36-39 knots.

And maybe they found a stretch of ocean sloping downwards for the speedtrials :D

 

But the fact remains that obviously the Iowa was capable of doing more then 31 knots.

 

 

 

I have always read in all sources that in wartime service the Iowas could reach a top speed of 33 knots...

 

Just a thing, though: in some circumstances the place of the speed trials did matter in terms of the actual results. Somewhere I read that (before 1914) the British Admiralty was puzzled by the fact that either destroyers or torpedo-boats weren't as fast as it seemed during speed trials; they eventually got an answer in the fact that those took place in the estuary of rivers, where the shallow depth enabled them to reach speeds that out in the open couldn't be reached.

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Just a thing, though: in some circumstances the place of the speed trials did matter in terms of the actual results. Somewhere I read that (before 1914) the British Admiralty was puzzled by the fact that either destroyers or torpedo-boats weren't as fast as it seemed during speed trials; they eventually got an answer in the fact that those took place in the estuary of rivers, where the shallow depth enabled them to reach speeds that out in the open couldn't be reached.

 

Is it not the other way around? It's less salinity in rivers->the density of water are closer to 1000 kg/m³ instead of 1025 (sea water), meaning that they will have an increased draft in rivers. And in most cases more draft equals more hull resistance.

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Guess in the case of small ships like torpedoboats and small destroyers, the advantage of a riverbed without any significant waves outweighs the the little increased draft of saltwater.

 

Guess also that the instruments used for the various speed tests were not always calibrated probably leading to different results.

Also most armies, navies, airforces like to be a bit creative when giving away data to the public. Especially in times when there are conflicts or conflicts are near, as having the biggest, fastets,.... give you some bragging rights and maybe forcing the other side to scrap projects and rethink.

 

 

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Is it not the other way around? It's less salinity in rivers->the density of water are closer to 1000 kg/m³ instead of 1025 (sea water), meaning that they will have an increased draft in rivers. And in most cases more draft equals more hull resistance.

 

It wasn't in the rivers, it was at the estuary of some, on shallow dephts; anyway, it was something I've read some time ago, and I'm now trying to find it again, so I can give a proper source.

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Well, shallow depths will do the same, increasing draft proportional with speed (Squat effect). So I still think the DDs must have been slower in the trials when compared to calm, open sea. But thanks for taking the effort, as now I'm curious if I'm right or wrong :honoring:

 

Edited by Vogel

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Shallow water increases speed according to the link I provided in my last post:

 

http://www.navweaps.com/index_tech/tech-029.htm

 

"Are there other ways to get these ships to go faster? If you want to "cheat" even further, you can imagine that you give the bathers along the Delaware coast a real thrill and operate the speed trials much closer to shore than is customary in order to get a bottom effect advantage"

 

I'm speculating it may be something similar to ground effect for airplanes, lift increases when flying low because you the air pushes against the solid ground, so in a similar fashion if the ship can't push the water down it may cause the ship to sit slightly higher in the water thus reducing water resistance.

 

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As a nautical engineer ( a bit prematurely, as I'm working on my master thesis), I think that statement is wrong. You will actually get added resistance in shallows in comparison to deep water. much due to squat. Additionally, the ship will generate more waves (due to the water cannot simply "escape" under the vessel anymore) in the bow area, hence more resistance. Over the surface on the the other hand, you'll get ground effects. The difference being that water is nearly incompressible, whereas air is not. So since you cannot force the water under the keel of the vessel, it has to go somewhere else->more waves.

 

I'm just curious if that's the conclusion the British discovered during their speed-trials

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I am still looking for the reference which I've seen (sorry, I have so much stuff I can't remember where it was exactly).

 

But I found this that, although a different situation, I believe is compatible with what I've described: it details the speed trials of HMS Cossack, and while it admits that in shallow waters the initial power output needed is greater, the ship actually went faster than in deep waters because it later "rode the hump" (whatever that means, I'm no water physics expert).

 

http://www.navweaps.com/index_tech/tech-091.htm

Edited by Historynerd

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Interesting. I've only coma cross that shallows increase resistance in shallow water, but it would seem that enough speed will decrease resistance. Anyhow, thank you for the effort.

 

EDIT: If I understand it correctly, then the maximum wave resistance peak is lower in shallow water. And if he vessel is able to overcome this resistance, it will generate a different wave system. This new system will induce a lower resistance on the hull in comparison to infinite water depth. In deep water, this hump does not exist, so the total resistance will always be higher until the vessel starts to semi-plane :P.

 

 

Edited by Vogel

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I am still looking for the reference which I've seen (sorry, I have so much stuff I can't remember where it was exactly).

 

But I found this that, although a different situation, I believe is compatible with what I've described: it details the speed trials of HMS Cossack, and while it admits that in shallow waters the initial power output needed is greater, the ship actually went faster than in deep waters because it later "rode the hump" (whatever that means, I'm no water physics expert).

 

http://www.navweaps.com/index_tech/tech-091.htm

 

No, what that graph tells you is that for shallow waters speeds:

 

16-21 knots there is a large increase in power needed to gain speed ( more power needed then same speed in deep water ).

21-28 knots there is almost no increase in power needed to gain speed ( gaining back and surpassing deep water ).

28 knots+ similar increase in power needed to gain speed, but speed will always be around 1.5 knots higher in shallow water then in deep for the same power.

 

 

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No, what that graph tells you is that for shallow waters speeds:

 

16-21 knots there is a large increase in power needed to gain speed ( more power needed then same speed in deep water ).

21-28 knots there is almost no increase in power needed to gain speed ( gaining back and surpassing deep water ).

28 knots+ similar increase in power needed to gain speed, but speed will always be around 1.5 knots higher in shallow water then in deep for the same power.

 

 

 

As I said, no expert. Thanks for correcting me. :hiding:

Edited by Historynerd

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As I said, no expert. Thanks for correcting me. :hiding:

 

No I'm sorry. I misread the first time and thought you wrote that ships at deep water would reach higher top speeds :(

 

Thanks for the link, it was a very interesting read!

 

I think we all agree now at least that faster warships at shallow water will reach higher maximum speeds then they would at deeper water.

 

I found a comment describing the effects of shallow water further:

 

"It is believed that this event occurred due to the shallow water depth and the deep draft of the vessel resulting in the ship being partially lifted by the displacement of the water from the ship's passing creating a pressure wave beneath the hull."

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