1939 Battleship Forces: US Navy vs Royal Navy

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby Djoser » Wed May 13, 2015 11:50 am

In an alternative world history pitting the US vs the British, I doubt very much that there would be the identical German, Russian, & Japanese states. I suspect that a lot more would change than just this one particular conflict. Say the Germans were not humiliated and saddled with such enormous indemnities post WW I? So no Nazi takeover, and probably not the enormous resurgence in militarism in Germany.

Interesting about the deck armor weakness in the US BBs, I was not aware of that. So at longer ranges definitely a near even fight--presuming the USN has improved its gunnery substantially from the abysmal standards of 1917. If 'Ching' Lee had his way, the USN gunnery might well be better than the Brits. Assuming identical gunnery skill, at closer ranges I suspect the three British BCs would not hold up well, and once they were out of the fight, the already fairly substantial edge in broadside weight possessed by the USN would mean victory. Albeit at a probable high cost.

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby Garyt » Thu May 14, 2015 12:23 am

From what I have read, British armor was about 15-20% more effective than US armor - which would mean there would be an advantage for the Brits.

Also, IIRC when the US battleships were modernized they did not replace their existing armor, they added to it. So we would have better quality armor layered over lesser quality armor.

Of course I think the Brits did the same, not replacing but adding to armor when they modernized the vessels.

A study of the types of armor on the battleships in addition to thickness would probably be helpful here.

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby alecsandros » Thu May 14, 2015 9:28 am

... 1939, British had 12 old battleships and 3 old battlecruisers, mounting 100 x 15" guns, and 18 x 16" guns or 105 tons broadside weight

while the Americans had 16 old battleships, mounting 12 x 12", 112 x 14", 24 x 16" guns, or 110 tons broadside weight.

Given the fact that the USN had considerably more battleship gunnery training in concentrated fire, my guess is the first chance goes to them.

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby Dave Saxton » Thu May 14, 2015 3:36 pm

Garyt wrote:From what I have read, British armor was about 15-20% more effective than US armor - which would mean there would be an advantage for the Brits.

Also, IIRC when the US battleships were modernized they did not replace their existing armor, they added to it. So we would have better quality armor layered over lesser quality armor.

Of course I think the Brits did the same, not replacing but adding to armor when they modernized the vessels.

A study of the types of armor on the battleships in addition to thickness would probably be helpful here.


In terms of WWII era armour US face hardened armour was less effective than British face hardened armour. When US began producing face hardened armour once again after the hiatus, its quality was found sub par.

Nonetheless homogenous rather than face hardened armour is what concerns us in terms of deck protection. How should we quantify the various types of homogenous armour, and protective deck plating, and high tensile steels, and low tensile steels? Tensile strength, hardness, ductility, composition? For our purposes, effective thickness is the best way to quantify these. For example, if it takes 10% more kenetic energy to penetrate a given thickness of 1 type of armour than it does to penetrate the same thickness of a 2nd type of armour using the same shell type; it is the same as if the first type is 10% thicker. What should the standard be though? WWII era homogenous armour should probably be the standard, but should it be STS, NCA, Wh, MNC? It took about 8% more energy to penetrate German Wh than it did British NCA with non-capped projectiles in post war tests. But what about capped projectiles? The Germans had evidence that indicated that homogenous armour containing molybdenum performed better during oblique impact than a similar armour with no Mo. The British WWII NCA had Mo and USN STS did not. Yet most charts will assume these two as of equal quality. What about the French homogenous armour that at 155mm effective was defeated by a US 16" shell at only 24,000 yards? Does this indicate exceptionally poor quality or are there other factors at play here?

Most WWII armours are probably pretty close for our purposes to just use an effective thickness estimate. How should such an estimate be made? What about in the case of old USN BBs where there is a mixture of armour grade steels laid over top of non armour grade steels? In this case there is a huge disparity in terms of tensile strength but not of ductility. Mild steel has about 1/2 the tensile strength of STS and normal levels of hardness, of 225 bn for the STS and 150 bn for the MS (tensile strength increases with hardness but ductility decreases, and this is what makes armour grade steel special because it can provide significantly higher tensile strength at acceptable levels of ductility. And German Wh was clearly the best in terms of these parameters). Tensile strength is a primary factor in resistance to perforation, because for the material to be perforated it must be stretched and torn apart (Yield strength being the force exerted to begin to stretch the material and ultimate tensile strength being the amount of force to finally cause it to tear apart, and % elongation the amount it stretches between these two.) We can safely assume that a given thickness of MS is about 1/2 the effective thickness of the same thickness of STS. In the case of the West Virginia we have 1.5" of STS laid over top of 1.5" of MS. The British found that two plates in direct contact had less effective thickness than if the two plates were spaced. And the Germans found that most multiple plates systems can be estimated for effective thickness by using this formula: Square root (p1^ +p2^ +p3^...). In the West Virginia case: sq root ((.5 x 1.5)^ + 1.5^ + splinter deck^)
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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby Garyt » Thu May 14, 2015 6:50 pm

And the Germans found that most multiple plates systems can be estimated for effective thickness by using this formula: Square root (p1^ +p2^ +p3^...). In the West Virginia case: sq root ((.5 x 1.5)^ + 1.5^ + splinter deck^)


This is a very important issue IMO. This was my biggest point when in modernization of battleships, armor was almost always added instead of replaced. And the added layer + existing layer certainly did not perform as effectively as if it would have been 1 layer.

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby alecsandros » Fri May 15, 2015 6:42 am

Garyt wrote:
And the Germans found that most multiple plates systems can be estimated for effective thickness by using this formula: Square root (p1^ +p2^ +p3^...). In the West Virginia case: sq root ((.5 x 1.5)^ + 1.5^ + splinter deck^)


This is a very important issue IMO. This was my biggest point when in modernization of battleships, armor was almost always added instead of replaced. And the added layer + existing layer certainly did not perform as effectively as if it would have been 1 layer.

... A 1939 battleship encounter would be fought at 15-17km range, owing to limitations in rangefinding and ballistic accuracy.
This was the range-band at which both RN and USN performed vast majority of gunnery training (up to 19000y)

At 17km, the most probable hits would be on vertical surfaces, thus the importance of belt , turret and barbette armor.

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby Steve Crandell » Fri May 15, 2015 7:42 pm

As opposed to the Sinking of HMS Glorious in 1940 with a hit at 27,000 yds?

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby Garyt » Sat May 16, 2015 4:30 pm

... A 1939 battleship encounter would be fought at 15-17km range, owing to limitations in rangefinding and ballistic accuracy.
This was the range-band at which both RN and USN performed vast majority of gunnery training (up to 19000y)


If Steve Lorenz has his ballistics right, which I'm pretty sure he does as his work is well researched, a hit at 15-17km should still fall against the horizontal armor around 30-40% based on the ballistics of most battleship guns.

And there were certainly hits, even early war beyond the 15-17 range. even at Denmark straight, Hood opened up fire at 24km.

I don't think battleship battles were fought at a particular "range", I think they opened fire when they felt they had any chance of hitting something (seems to be in the 20k-30k range), and continued to close the range until at point blank (point blank for a naval cannon that is) as long as they survived. Any substantial damage or loss of one's own forces to the point of being outnumbered may result in the "losing" side seeking to disengage.

Unless you had a running battle, where one sde was seeking to disengage.

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby alecsandros » Sat May 16, 2015 4:45 pm

Steve Crandell wrote:As opposed to the Sinking of HMS Glorious in 1940 with a hit at 27,000 yds?

... That was by radar-directed fire, which would not be the case for a 1939 full gunnery battle between USN and RN...

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby alecsandros » Sat May 16, 2015 4:48 pm

Garyt wrote:
... A 1939 battleship encounter would be fought at 15-17km range, owing to limitations in rangefinding and ballistic accuracy.
This was the range-band at which both RN and USN performed vast majority of gunnery training (up to 19000y)


If Steve Lorenz has his ballistics right, which I'm pretty sure he does as his work is well researched, a hit at 15-17km should still fall against the horizontal armor around 30-40% based on the ballistics of most battleship guns.

And there were certainly hits, even early war beyond the 15-17 range. even at Denmark straight, Hood opened up fire at 24km.

I don't think battleship battles were fought at a particular "range", I think they opened fire when they felt they had any chance of hitting something (seems to be in the 20k-30k range), and continued to close the range until at point blank (point blank for a naval cannon that is) as long as they survived. Any substantial damage or loss of one's own forces to the point of being outnumbered may result in the "losing" side seeking to disengage.

Unless you had a running battle, where one sde was seeking to disengage.


... British doctrine emphasized the 12 - 18km band range for capital ships engagements. USN doctrine presumed initial long-range shooting.

In 1939 most, if not all available battleships were not fitted with radars for gunnery, or capable of supporting gunnery.
Thus the rangefinding would be almost entirely by visual rangefinding, which gave it's best results (for the 1915-1927 ships involved) below 20.000yards.

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby Garyt » Sat May 16, 2015 7:23 pm

Thus the rangefinding would be almost entirely by visual rangefinding, which gave it's best results (for the 1915-1927 ships involved) below 20.000yards.


Yamato, working on visual, was able to obtain a hit on White Plains at 30k + Yards, and hit a destroyer at about 30k yards.

I know Japanese optics were good, but I don't think they were head and shoulders above British or US optics.

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby Steve Crandell » Sun May 17, 2015 12:03 am

Garyt wrote:
Thus the rangefinding would be almost entirely by visual rangefinding, which gave it's best results (for the 1915-1927 ships involved) below 20.000yards.


Yamato, working on visual, was able to obtain a hit on White Plains at 30k + Yards, and hit a destroyer at about 30k yards.

I know Japanese optics were good, but I don't think they were head and shoulders above British or US optics.


I believe Yamato's optics actually were head and shoulders above anyone else's, just based on the main director's height above water and the fact that it had a long base rangefinder found in other navies only in turrets, much closer to the water and therefore useless at extreme ranges.

The whole idea of the USN pre war emphasis on long range gunnery involved aircraft spotting for battleship gunnery. They weren't planning to depend on the ship's optics at that range except for bearings.

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby Dave Saxton » Sun May 17, 2015 1:00 am

Garyt wrote:
Yamato, working on visual, was able to obtain a hit on White Plains at 30k + Yards, and hit a destroyer at about 30k yards.


Yamato could have used radar ranging. Although it did not have a firecontrol radar capable of blind fire, its surface search sets had a range accuracy of 100 meters. Ranging is the most important thing. It is an equalizer. Once one can accurately range one can hopefully combine it with optics. Even those that possessed more advanced firecontrol radars preferred to combine radar ranging with optics if at all possible, even late war.

The whole idea of the USN pre war emphasis on long range gunnery involved aircraft spotting for battleship gunnery.


At River Plate, which was fought during late 39, The British utilized both aircraft spotting and concentrated fire. I would expect both sides to attempt this and to be fairly proficient.

British doctrine was to attemp to close to 12,000 yards and to force a quick decision one way or the other, though. The British will have a speed advantage.
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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby alecsandros » Sun May 17, 2015 11:58 am

Garyt wrote:
Thus the rangefinding would be almost entirely by visual rangefinding, which gave it's best results (for the 1915-1927 ships involved) below 20.000yards.


Yamato, working on visual, was able to obtain a hit on White Plains at 30k + Yards, and hit a destroyer at about 30k yards.

I know Japanese optics were good, but I don't think they were head and shoulders above British or US optics.

... Yamato was comissioned in 1942,
and in the 1939 RN and USN battlelines there wasn't any rangefinder remotely similar in performance to the mammoth 15meters baselength installed on the Japanese battleship.

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Re: 1939 Battleship Forces: US Navy vs Royal Navy

Postby Thorsten Wahl » Mon May 18, 2015 6:57 pm

for comparison Graf Spee ranges for optical detection
during its south atlantic journey 1939
Graf Spee is acounted for ranging on clouds of smoke from stacks at distances greater then 40 km
on 10.10.1939 44 km (steamer Huntsman)
ships wth modern fire facilites at lower distances
typical detection range on the day against merchant ships 35 km (clear horizont provided)

Yamato could have used radar ranging. Although it did not have a firecontrol radar capable of blind fire,

this appears as questionable, when the US CVEs entered the rain squall cease fire was observed.
USS Heerman used the rain squall for several succesful surprise attacks this seems to be impossible if the Japanese used radar for tactical purposes.
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