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Krakatoa
Post subject: Superfiring Nassau class battleships 1909-10Posted: June 18th, 2017, 12:54 am
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Following on from the cruisers and battlecruisers, comes the Nassau class battleships.

Following the American South Carolina innovation of superfiring turrets, the Germans hold an advantage in only requiring the four turrets to produce an eight gun broadside while the British ships need five turrets to have their eight gun broadside on Dreadnought to St Vincent class dreadnoughts. The advantage is lessened by the 11" main guns versus the 12" main guns being put aboard the dreadnoughts of the rest of the world.

The removal of the awkward wing turret design planned for these ships allows for more armour and greater speed over those ships fitted with 'wing' armaments. The only remaining disadvantage was the retention of the triple expansion engines for the first two ships of the class, the new turbine machinery not being ready. The later two ships were fitted with the new turbine installations. The first two ships could have been retroactively fitted with turbines but cost, time and production bottlenecks made this impractical.

[ img ]


Displacement: 19,500 tons normal, 22,750 full load displacement.
Dimensions: 534 x 90 x 29 feet
Machinery: 3 shaft, triple expansion, 26,000ihp or 3 shaft, steam turbine, 30,000shp
Speed: 22 knots (triple) 23.5 knots (turbine)
Endurance: 8,500 nmi at 12 knots
Armour: 330mm belt, 60mm deck, 280mm/210mm/105mm turrets
Armament:
8 x 11" (4x2)
12 x 5.9" (12x1)
8 x 3.4" (8x1)
Torpedoes: 6 x 18" (6x1 underwater)
Crew: 1000 (1090 as flagship)


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Imperialist
Post subject: Re: Superfiring Nassau class battleships 1909-10Posted: June 18th, 2017, 1:43 am
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Looks real pretty, good job there :)

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acelanceloet
Post subject: Re: Superfiring Nassau class battleships 1909-10Posted: June 18th, 2017, 11:12 am
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With your dimensions, I reached a ship of about 23000 tons standard displacement (seeing that the block coefficient would not vary much, it might even go up as you seem to have lengthened the bulky midship section). Instead of the 750 tons you added, I would thus see 4000 tons added. Indeed, enough free weight to increase armour, and the additional speed would, even with the same machinery, result from the longer hull. You did however add a full deck on the superstructure, a deck containing turrets and secondary guns and because of that armour, so I would think the center of gravity would go up. I am not familiar with these ships so I do not know much about their stability, but I do think most of the saved and additional weight would have to go low in the ship, as the centre of gravity went up but the beam was not increased. This might result in armour that is actually weaker above the waterline, as it needs to be spread over an larger area.

In short, the ship as you have drawn now, does not offer any significant advantages over the original design in my opinion. It could....... but you would have to remodel more to do so, I think. Or less, because lowering the secondary guns one deck again might offset the topweight significantly.

Btw, the germans might have an broadside of the same size, but what about this: the original, smaller, design had the same broadside but also had 6 guns or more available to fire in ANY direction, while this larger variant only has 4 or more available on part of their arcs. The Dreadnought also had 6 or more available on all arcs, when chasing or being hunted these ships might be at an disadvantage...... which was IIRC an common kind of battle on the North Sea?

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Krakatoa
Post subject: Re: Superfiring Nassau class battleships 1909-10Posted: June 19th, 2017, 10:53 am
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Thanks for the comments Ace, unfortunately you forgot to take the two 11" turrets and all handling equipment down to the magazines, that were completely removed into your calculations. That is where your missing 3.500 to 4,000 tons has gone to and why I only add 500 tons to the original tonnage.

Moving the 5.9" battery up a deck makes the guns useful. Leave them in the original battery deck and they remain useless in anything except a flat calm. It always surprised me that these battery decks remained for as long as they did since the first guns were mounted that way in the 1890's and must have come across bad weather during those years.

I actually took 15 feet out of the central citadel after removing the wing turrets, then added another 60 feet back in for the added superfiring turrets. Removing the wing turrets frees up a lot of space in the area where the larger propulsion system was to be fitted.

Being 1 or 2 knots faster than the RN ships does mean they might be chased but they are going to be tough to catch.


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acelanceloet
Post subject: Re: Superfiring Nassau class battleships 1909-10Posted: June 19th, 2017, 7:49 pm
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Actually, I did not forget to take those turrets and magazines into account, I did not need them for my calculations.

displacement of a ship is literally the weight of the water the ship 'displaces' by being there. Displacement can thus be measured from the weight of the ship or by the volume of the water that is not there because the ship is there. I used the second method: by taking the measurements you gave and the block coefficient of the real life Nassau ships (about 0,55), I reached 23000 tons. As you have drawn her, with hull shading which is mostly parallel in the midship section (the forward 'hump' and the start of the stern going up are almost exactly the same as on the original Nassau, so you lengthened her in the midship section only) means the block coefficient would be even higher, so the weight would be even higher as well.

moving the guns up one deck might make them useful, but there are reasons why they remained so low. stability and weight are very important ones, I think. Just heightening the armoured citadel deck, with no supporting structures or decks taken into account, would be about 500 tons if the armour would be 0,2 m thick and made of normal steel. I estimate that bringing that deck up would bring the center of gravity up with at least 10 cm, an let's assume the higher turrets do the same. On a metacentric height (one of the most important measurement tools for stability) of about 1.5 meters, this would be an significant loss of stability. This is generally enough to make the battery deck useless in anything but a flat calm again, because otherwise the ship is moving too much for them to be aimed properly!

I am not convinced about the bigger propulsion system, the funnels and the machinery length remains much the same. I am not familiar enough with their machinery arrangement to say much about that though.

1 or 2 knots faster then they were would already be reached with the longer hull I think, but hindsight learns us that they already were quite hard to catch. I am not certain though, if that really offsets the loss of the end-on guns........

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Krakatoa
Post subject: Re: Superfiring Nassau class battleships 1909-10Posted: June 19th, 2017, 9:30 pm
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Ace, you have to take the removal of a third of the main armament into your calculations. The block coefficient you are going on about is for the Nassau class as they were at normal conditions. You take a third of the main armament off that ship and its block coefficient is going to change too.

Removing the wing turrets is going to free up a lot of space. My approximate working figure was 250 cubic metres that could be used for extra propulsion and other bits and pieces in the central citadel.

If the wing turrets were so good, why was every country in such a hurry to get rid of them?


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acelanceloet
Post subject: Re: Superfiring Nassau class battleships 1909-10Posted: June 19th, 2017, 10:02 pm
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I took the time to do some more thorough calculations of both the block coefficient of the nassau class and of your ship. I got to a slightly lower number for both. as you can see below, no differences in conditions for both ships: I took the same kind of measurements for both.

Nassau class displacement in normal conditions: 18,873t / (146.1 m * 26.9 m * 8.76 m) = 0,548

Superfiring Nassau class displacement in normal conditions:
162.76m * 27.4m * 8.83m * 0,548 = 21579t

Also, if I use block coefficient and draft in normal conditions of the nassau, and I use that same standard for your ship, I have your ship in normal conditions as well.

The additional space, was it actually usable? what did you change in the boiler arrangements and machinery that you could actually use that additional space? boilers require uptakes, and you mostly win beam space, which is hardly usable for machinery (as the engines require inline length, and you cannot overlap them next to each other as there need to be transverse watertight bulkheads)

and hey, I have no idea why they first used beam turrets and later superfiring, I would have to look into that. however, I do know that when you have a bigger ship with less guns and about the same in every other respect, something is going not exactly right.

btw, don't get me wrong. I am not saying your idea is impossible. I am just saying that this drawing and specs are not what this concept represents, as they mismatch. Building an german dreadnought with superfiring turrets should be possible, but as I said, this design has topweight issues, is quite a bit bigger in all dimensions and has drawbacks in certain areas which were important in the doctrine and tactics of the time, IIRC. You should do some thinking on this design and make it work, my purpose is not bashing it in, my purpose is improving it.

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Krakatoa
Post subject: Re: Superfiring Nassau class battleships 1909-10Posted: June 20th, 2017, 1:58 am
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Nassau class displacement in normal conditions: 18,873t / (146.1 m * 26.9 m * 8.76 m) = 0,548

The 8.76m is the depth of the hull with ALL the armament aboard. Take away a third of the armament, then that is going to reduce the draught, and therefore the block coefficient is going to be different. Surely that makes sense?


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acelanceloet
Post subject: Re: Superfiring Nassau class battleships 1909-10Posted: June 20th, 2017, 6:48 am
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Well........

It is very much possible for a ship with a longer hull and no beam turrets to have an lower block coefficient. the midships cross section could be rounder and the bow and stern could be a lot finer. This has very little to do with the armamement (as that is only between 5 and 10% of the displacement normally, IIRC) but with the hull shape. You currently have not drawn a finer ship though: the hull shading and the location of propellers has not changed from the original Nassau.

If I assume your numbers are correct, you reach an block coefficient of 0.5, which I think is a bit on the low side for an battleship.

And again, I did not look at all at what you placed on board or removed for this calculation, I just took your ships dimensions and the hull shape you drew.

But I would not be surprised if she ended up being heavier, removing the turrets means losing 400 tons each, so 800 tons..... but you moving 2 turrets up would be more then 300 tons too, and moving the battery deck up would be 500 at least, bigger machinery, longer hull ( so more longitudinal reinforcements) and of course the higher topweight requires more weight low in the hull....... and you list a longer range with more powerfull machinery, so that would require a significant update in fuel storage as well.

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Tempest
Post subject: Re: Superfiring Nassau class battleships 1909-10Posted: June 20th, 2017, 10:58 pm
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Great drawing Krakatoa, I'm not sure though, it seems 'too modern' for the time frame.
acelanceloet wrote: *
I have no idea why they first used beam turrets and later superfiring, I would have to look into that.
The Germans were worried at the time the the superfiring turrets would somehow damage the other turret below, also (I think) there was the worry of the turret crew becoming incapacitated. The other concern was one direct hit could put both turrets out of action.

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