AHC/WI: Faster Nelson class?

[CaptainCalvert]

The French one also has what looks suspiciously like a wine cask (and a half barrel) in front of the turret.
I like the idea of a full weight 16" shell but presume it would be fired slower to give similar total muzzle energy? I was thinking about how much extra damage would be caused to the NelRods when firing a full weight shell at the same speed.

 

[steamboy]

The muzzle velocity would be lower yes, but you've still got the kinetic impact of the heavier if slower round and a larger bursting charge. So six of one half a doze of the other really if it was a heavier shell vs a higher velocity one. But if you could cut down on reducing the barrel life of the guns that would save money and refit time.

 

[fastmongrel]

I read somewhere that the light 16" shell was designed for penetrating vertical armour at relatively short range up to about 15,000 yards. With better optics and spotting aircraft battle ranges increased and penetrating horizontal armour became the requirement. A new heavier deck piercing shell was designed but there was magazines full of the light shell and wartime is not a good time to mess about with new untested things especially in the 1939 to 1942 period.

 

[BobTheBarbarian]

Sure is a KGV? The bridge tower looks too frenchy for my taste, May it be Jean Bart damaged turret in Casablanca?

It's supposed to be a French battleship; the question was whether the Richelieus had single or double gun cradles.

 

[Paul_Sussex]

The reconstructed Conte di Cavours managed 27 knots on two shafts and 75,000shp. If the Nelrods had been designed without the conning tower and torpedo tubes, with a transom stern and the machinery from an Amphion or Leander, would that get them close to 27/28 knots? Would there be space within the existing hull volume? I imagine something like this -

(Original drawing by Jabba on Shipbucket)

 

[ArtosStark]

The reconstructed Conte di Cavours managed 27 knots on two shafts and 75,000shp. If the Nelrods had been designed without the conning tower and torpedo tubes, with a transom stern and the machinery from an Amphion or Leander, would that get them close to 27/28 knots? Would there be space within the existing hull volume? I imagine something like this -
View attachment 742204

(Original drawing by Jabba on Shipbucket)

Well, they were 10,000 tons lighter than the Nelson class. That would certainly help.

The conning tower certainly could have been done without but it adds up to 222 tons. Not decisive on its own. Not sure how much weight the torpedoes cost. Another weight saving could be in secondaries. The 6” turrets were overweight. They were originally supposed to be 48 tons. This got pushed to 60, and they eventually came in at 77. 6” secondaries was, IMO, a mistake from Iron Duke to Nelson. A gun in the 4.5-5.5” range would likely have been better (the later 4.7” was 25 tons).

Based on the information that the British had at the time a transom stern was only useful above 25 knots. It actually had a slight detrimental effect in midrange speeds. So if they had been going for 27 knots + then they probably would have gone for a transom.

 

[Schlock]

The NelRods machinery apparently made 23.4 shp/ton, which allowed them to make 23 knots on 45,000 shp. If you built them up to the 35k std limit, you'd probably give them about 60,000 shp going by the rule of thumb that you'd use around half of that extra displacement in protection. The other rule of thumb is that you need to double your installed power for every four knots of speed, so likely a NelRod built with 60,000 shp would be capable of about 24.5 knots or so.

The fun bit happens if you suddenly allocate that 'extra' 3000 std tons of modernisation allowance ala the Lexingtons on top of that. Suddenly we're looking at a 38,000 std displacement Fast Battleship with 95,000 shp installed power, which has doubled your installed power and would likely have been built with a transom stern. I'd give it a conservative estimate of 27 knots and could probably be pushed to 28.5 if overloaded hard like historically was done.

 

[USS_Ward]

The 6” turrets were overweight. They were originally supposed to be 48 tons. This got pushed to 60, and they eventually came in at 77. 6” secondaries was, IMO, a mistake from Iron Duke to Nelson. A gun in the 4.5-5.5” range would likely have been better (the later 4.7” was 25 tons).

I’m honestly surprised they weren’t ditched in a refit and replaced w/ 4.5 inch, 4.7 inch or the 5.25.

The fun bit happens if you suddenly allocate that 'extra' 3000 std tons of modernisation allowance ala the Lexingtons on top of that. Suddenly we're looking at a 38,000 std displacement Fast Battleship with 95,000 shp installed power, which has doubled your installed power and would likely have been built with a transom stern. I'd give it a conservative estimate of 27 knots and could probably be pushed to 28.5 if overloaded hard like historically was done.

A ship capable of chasing down the Bis, Tirpitz or the Twins. Probably would have put the Admiralty at ease especially in that tenuous time period of early-mid 1942 when the only fast battleship capable of going toe to toe and possibly standing a chance against Tirpitz was the KGV. Two extra fast battleships that are even more powerful then the KGV’s would be real helpful.

 

[CV12Hornet]

I’m honestly surprised they weren’t ditched in a refit and replaced w/ 4.5 inch, 4.7 inch or the 5.25.

That's not major ship surgery, but it's significantly more work than with the old-school casemates. The Brits couldn't even find the time to keep Rodney's machinery in decent condition. Replacing the secondaries was assuredly very low down their list of priorities.

 

[Peg Leg Pom]

I’m honestly surprised they weren’t ditched in a refit and replaced w/ 4.5 inch, 4.7 inch or the 5.25.

The Nelrods were comparatively new ships, well down the que for the sort of refit or rebuild that involves changing the secondary armament.

 

[Marquis]

My solution to a better RodNol would have included starting off with a 15" gun (Vickers-Armstrong 15-inch 45-calibre Mark B being my preference). Then no torpedo tubes, no 6" guns, no conning tower. I think there was also a clause somewhere allowing was it 2500 tons for refits (bulging and AA basically). So completely dump the AA and add it in a refit. Also the French could get 10,000shp worth of steam out of a boiler at this time, so why couldn't the RN get 80k shp from 8?

Also on the subject of the French, they had the quadruple turret designed for the Normandies. I would have bought a couple of those from them for testing, potentially with a view to designing a British variant. Potentially delay the Rodnols a couple of years while actually hammering out design decisions (and allowing propulsion technology to evolve).

 

[CV12Hornet]

My solution to a better RodNol would have included starting off with a 15" gun (Vickers-Armstrong 15-inch 45-calibre Mark B being my preference). Then no torpedo tubes, no 6" guns, no conning tower. I think there was also a clause somewhere allowing was it 2500 tons for refits (bulging and AA basically). So completely dump the AA and add it in a refit. Also the French could get 10,000shp worth of steam out of a boiler at this time, so why couldn't the RN get 80k shp from 8?

They could. And did on the County-class cruisers being built at the same time. And just chose not to for the Nelsons.

 

[1Big Rich]

The 6” turrets were overweight. They were originally supposed to be 48 tons. This got pushed to 60, and they eventually came in at 77. 6” secondaries was, IMO, a mistake from Iron Duke to Nelson. A gun in the 4.5-5.5” range would likely have been better (the later 4.7” was 25 tons).

I think the 6in was carried because it was the armament of the last dreadnoughts, and was to provide stopping-power against light cruises (and destroyers). The AA doctrine of the time was barrage fires, so a uniform secondary battery of a lighter caliber could have provided a good barrage for AA work as well as a volume of fire for fending off light forces.

I've often wondered of the seeming schizophrenia of the largest navy in the world worried about its capital ships being without escort. "A turret must be able to fire at zero degrees elevation dead ahead" the heavier secondaries like the 5.25in for 'anti-cruiser' work. I can think of only two occasions where an allied battleship was alone without escort in hostile waters with a chance of meeting enemy light forces (cruiser or smaller); King George V during the Bismarck chase, when the rest of the fleet departed for Iceland to refuel and Washington during Second Guadalcanal. We could throw in Hood and Prince of Wales at Denmark Straight as well, but that was a conscious choice by Holland to send all his escorting destroyers north to search for the enemy.

I’m honestly surprised they weren’t ditched in a refit and replaced w/ 4.5 inch, 4.7 inch or the 5.25.

As I recall, the proposed rebuild of Rodney was to include a cross-deck catapult and changing the 6in and 4.7in for eight 5.25in. There was also a plan to rearm Nelson with 5in/38s before the US entry into the war ended the project.

That's not major ship surgery, but it's significantly more work than with the old-school casemates. The Brits couldn't even find the time to keep Rodney's machinery in decent condition. Replacing the secondaries was assuredly very low down their list of priorities.

Overtaken by events. The second half of the '30s saw Europe lurch from one crisis to another, the Spanish Civil War, the Abyssinian Crisis, the annexation of Austria, the Sudetenland, etc. The largest and most powerful ships in the RN, Hood, Nelson and Rodney were very much in demand. And Nelson and Rodney were actually ahead of Hood in the rebuild schedule because of the pathetic state of their electrical systems.

My thoughts,

 

[Paul_Sussex]

My solution to a better RodNol would have included starting off with a 15" gun (Vickers-Armstrong 15-inch 45-calibre Mark B being my preference). Then no torpedo tubes, no 6" guns, no conning tower. I think there was also a clause somewhere allowing was it 2500 tons for refits (bulging and AA basically). So completely dump the AA and add it in a refit. Also the French could get 10,000shp worth of steam out of a boiler at this time, so why couldn't the RN get 80k shp from 8?

They could. And did on the County-class cruisers being built at the same time. And just chose not to for the Nelsons.

My query is more to do with volume than weight. How much space does doing away with the conning tower and torpedo room buy in terms of rearranging internals and allowing more boiler room and engine room space? If...

...the Rodney apparently hit 25 knots during the Bismarck chase by forcing the ever loving crap out of her engines, so if the engineers of a 25 knot capable version did the same, they could probably wring a knot or two out of the engines if needed...

...and you could get something like the 80000shp of the Counties into the same hull form, what might be a possible speed? As much as 27 or 28 knots?

 

[ArtosStark]

I think the 6in was carried because it was the armament of the last dreadnoughts, and was to provide stopping-power against light cruises (and destroyers)

Probably. The original switch to 6” in Iron Duke was justified due to the increase in the size and survivability of enemy destroyers, as the previous jump to 4” secondaries had been. However, there was a significant amount of the old pre-dreadnought “hail of fire” thinking in there. They would have been better to have kept smaller guns in turrets or on deck IMO. And with Nelson they probably would have been better served by 10 or 12 twin 4.7” at 25 tons each (250 or 300 tons, not including shell rooms) than 6 twin 6” at 77 tons each (462 tons).

 

[ArtosStark]

and you could get something like the 80000shp of the Counties into the same hull form, what might be a possible speed? As much as 27 or 28 knots?

It should make 27, or almost 28.
Rule of thumb for the same hull is take the difference in speed (28/23 = 1.22), cube it (1.22^3 = 1.80) and multiply it by current power (45,000 * 1.80 = 81,190).

So 80,000 shp should just about get the Nelsons to 28 knots. I am not sure what the relative dimensions of the plants in question were, so I can’t say if it would fit. The Counties may have had larger machinery, even if they had the same number of boilers. Even admiralty boilers could come in different sizes and the rest of the machinery makes a difference as well.

 

[alspug]

The single biggest problem is the hull shape. The British knew how to design hulls to get the speed they wanted and minimise the horsepower needed. If for example Nelson and Rodney had a hull with a transome stern and 140,000hp maybe just maybe they could have achieved 28 knots.

BTW
I do not pretend to be an expert on the required SHP to achieve certain speeds, however I am aware of the relationship between SHP, Hull design and Tonnage to move.
I am also aware that the Royal Navy consistently needed less SHP to achieve the performance desired when compared to other nations. This is best illustrated by the "Treaty Battleships".

 

[Tangles2]

Here's a take for your general consideration. The scenario is that the RN is forced to revisit R & N designs after the initial poor results of the 16-inch trial. Under severe austerity guidelines Treasury forces a standardization of main armament calibers retaining well-tried 15" and 7.5" armament for the new BB and CA designs (no 14", 8", or 5.25" development costs. The revisit to design eventually produces a more traditional R & N design with nine 15-inch in three triple turrets. Trade-off in a slight reduction in armor belt but 26-27 knot speed with four screws. Here's my take for your collective raspberries. and amusement. Enjoy T

 

[SealTheRealDeal]

Here's a take for your general consideration. The scenario is that the RN is forced to revisit R & N designs after the initial poor results of the 16-inch trial. Under severe austerity guidelines Treasury forces a standardization of main armament calibers retaining well-tried 15" and 7.5" armament for the new BB and CA designs (no 14", 8", or 5.25" development costs. The revisit to design eventually produces a more traditional R & N design with nine 15-inch in three triple turrets. Trade-off in a slight reduction in armor belt but 26-27 knot speed with four screws. Here's my take for your collective raspberries. and amusement. Enjoy T

But the 8" gun and mount was MUCH better than the 7.5", why ya gotta screw the Counties like that?

 

[Tangles2]

But the 8" gun and mount was MUCH better than the 7.5", why ya gotta screw the Counties like that?

The god of the bottom line, is money. Remember it's an austerity-driven push from the treasury in a postwar environment where there is little incentive or public support for military spending and when political imperatives prioritize social welfare and support measures. Also, the 8-inch was still not yet a common caliber, it was the WNT that led to its widespread adoption. At this time the 7.5 and 9.2 inch were both proven guns with reliable designs and track records, whilst the 8" was in its development phase and much of its promise (70-degree elevation?) was just speculation without practical support. Also with the scrapping of many of the WW1 armored cruisers also a great number of low-usage barrels were available and once refurbished available to be reused as a cost-saving. It wasn't a bad weapon of its type and being lighter offered the ability for installing increased numbers at less weight than the newer design. Just look at the resulting development costs that the 14" had and problems, as well as the twin 8" turret initially and later the 5.25-inch cost. All of these involved both a great deal of development time and money and an argument can be made about whether could it have been better spent. Remember the 15-inch Mk1 was an excellent weapon in both terms of range and excellent ballistic performance, and the 50-caliber Mk2 had been designed and was probably just as good or better (proven heritage and lighter) before the 14" was forced as a politically expedient option by the treaty pundits. Also I think you are underselling the 7.5" consideration. It was proven, reliable, and with a large shell available with good ballistic capabilities even with only the 42-caliber version, and the larger gun only offered marginal improvement in size and range. it's easy to be a little bit blinkered by hindsight but I honestly can't say that early on the 8 and 14-inch choices weren't necessarily standout considerations, particularly if some penny-pinching bureaucrat from Whitehall is calling the shots (pardon the pun). My gut feeling using that hindsight is that the 14" was a poorer choice to the existing 15" options, whilst less certain on the call 7.5 vs 8-inch. For the R & N, I feel that it would have been far better with the earlier guns and savings (Commonality of ammo and weight savings) to supplement other design aspects like armor or speed.