Armour 7+ for KGV, Nelson but not for Iowa?

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Armour 7+ for KGV, Nelson but not for Iowa?

Postby DSV1 » Tue Apr 21, 2020 7:38 pm

Hi all

I am no expert do will ask openly why the Iowa's which were considered the best overall battleship design I would like to ask what parameters led to this.

I have a few naval books and after looking at a couple for Stats I am a bit puzzled why the Iowa class are not 7+ too ?


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Re: Armour 7+ for KGV, Nelson but not for Iowa?

Postby Greg Smith » Sun Apr 26, 2020 12:19 pm

I'm not a naval expert, but I think the answer is simply that the Nelson and George V had thicker armour.

According to Conway's Fighting ships:

Nelson: Belt 14", Bulkheads 12"
George V: Belt 15" Bulkheads 12"
Iowa: Belt 12", Bulkheads 11" *

The Iowa had better armour on its turrets, though.

Now whether the Iowa's later construction made it better defended, I'll leave to more knowledgeable people to discuss. :)

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Re: Armour 7+ for KGV, Nelson but not for Iowa?

Postby rbax » Sun May 31, 2020 12:24 am

Hi, I was part of the team who developed statistics for the ships and as a result I believe that I am able to provide some answers, first on how we derived armor levels and second to voice my opinion on what battleship was best. So the question is "What are you defining as best?" Best armored, best armed, best equipped, best anti-aircraft platform, speed, best sea boat, best all around...because each will give you a different answer.

So let's look at the ships with +7 armor and the Iowa...I'll exclude the never built classes like the N-class, Montana and Lion. That leaves:

King George V-Class +7 Armor
Nelson-Class +7 Armor
Yamato-Class +7

and the Iowa +6 Armor

Best Armor...recognizing that this is a game based on d6's there is a limit to how much variability you can generate from unarmored to max armored. So we stuck with the simplest approach which was thickness of armor....mostly belt armor, but also deck armor to determine if the ship should be considered to have an armored deck versus its armor rating. So, belt armor

KGV: Mid Belt Armor of 14.7 inches (Note that during World War 2, England had the best really thick armor in the world in terms of material and construction)

Nelson: Mid Belt Armor 14.0 inches

Yamato: Mid Belt Armor 16.8 inches (Note that Japan had some of the worst thick armor and it was generally considered to be about 84% as effective as British Armor) Thus really...14.1 inches.

Iowa: Mid Belt: 13 inches (12 inch main belt and a 1 inch inner splinter belt). Interestingly, the 12-inch armor was essentially limit the US could produce and still maintain the properer face hardening, any thicker and the armor became to brittle (That's why the Colorado class with its 13.5 inch belt was really no better than the 12-inch armor of the Iowa class). In addition, the design requirement for highs speed to keep up with the fast carriers meant that something had to give, and that was armor.

Now 1-inch may not seem to be allot of difference but it is and it also happened to be at the cutoff between +6 and +7 armor rating and it was decided to leave the Iowa at +6.

So best armor...Yamato but only though shear thickness and not quality.

Best Guns...Again, within the limits of a d6 system there are going to be some broad brackets...but.

KGV: 14-inch, 1590 lb APCBC, penetrating 29.2 inches of vertical armor at range 0 and 11.2 inches of deck armor at 36,000 yards (it could penetrate more but we are way over the horizon at that point.)

Nelson: 16-inch, 2,048 lb APCBC, penetrating 32.6 inches of vertical armor at range 0 and 12 inches of deck armor at 36,000 yards. Its really not all that much better than the KGV for armor piercing.

Yamato: 18.1-inch, 3,219 lb APCBC, penetrating 32.8 inches of vertical armor at range 0 and get this 9.2 inches of deck armor at range at 36,000 yards. So its really not all that much better than a Nelson at point blank range and its actually worse at long range. Why? Well Japan fell in love with the concept of "submarining" shells. They designed the shell with a nose and a tail that would allow it to travel straight and stay intact under water if it landed short, allowing it to continue on to hit the ship below the waterline. In doing so they gave up above armor piercing performance to support a 1 in a million short shot. Never over estimate the ability of people to out think themselves.

Iowa: 16-inch, 2,700 lb APCBC, penetrating 33.3 inches of vertical armor at range 0 and 11.5 inches of deck armor at 36,000 yards. So the Iowa is the best but not by much.

Winner: Iowa by a hair.

Best Equipped. The Iowa was equipped with armor class steel on all her interior steel structures. We're not talking armor just metal walling (1/8", 1/4" thick stuff). But the US used armor steel and everyone else used mild steel. Why? Cost...and availability, only the US was willing to spend the money and the resources on the added interior strength. Also, by 1945 the US had the best fire control system going, capable of firing at night while maneuvering and still having a chance of hitting something. The British were right there as well. The US had radar fire control on every single weapon except 20mm guns. The British had it on their secondary, octouple and quadruple pom-poms but they weren't quite as good as the US version. The Yamato had basic radar detectors and by 1945 a rudimentary ability to use their Type 22 as a main battery fire control but only for ranging and not night fighting. No secondary or anti-aircraft guns.

Winner: Iowa

"Anti-Aircraft" For comparison we'll use 1944, when everyone is cranking up their anti-aircraft guns.

King George V-Class: 16x5.25-inch (not a very good Dual Purpose weapon due to cramp turrets and slow traversing). 64x2pdr (Nice gun but getting long in the tooth with a shorter range then the 40mm boffers), and 38x20mm (the best light AA gun of the war) and 8x40mm boffers (the best medium AA gun of the war)

Nelson-Class: 6 x 4.7-inch (a somewhat antiquated weapon, in equally antiquated single open mounts), 48x2pdr and 41x20mm.

Yamato: 24x5-inch (a descent gun, a little slow firing but serviceable). 149 x 25mm (probably the worst primary AA gun of any fleet, low fire rate, light shell, lots of vibration, slow tracking, the list goes on) and 4 x 13.2mm machine-guns (when no one used MG any more because they lacked hitting power).

Iowa: 20x5-inch (best DP gun of the war, fact tracking, fast firing...the Japanese called it the 5-inch machine-gun) and with VT fuses was absolutely lethal to aircraft. 76 x 40mm boffers (the best medium AA gun of the war) and 68 x 20mm (the best light AA gun of the war)....see a theme?

Winner: Iowa

"Speed" For getting into and out of trouble.

King George V-Class 27.5 kts (casualty of Washington Treaty, to get the armor required lighter guns and less speed)
Nelson-Class 23 kts. (casualty of the Washington Treaty, to get the armor and the guns, meant even less speed)
Yamato: 27 kts (something that big only goes so fast and the Yamato was consider a masterpiece of hydrodynamic design)
Iowa: 32.5 kts (No treaty limit, advanced steam system delivering 212,000 shp and very long slender design to produce less drag)

Winner: Iowa. She pick the range at which combat can occur, get away if things go badly and maintain contact if the enemy tries to get away.

Best Sea Boat. This is a bit of opinion driven more by anecdotal evidence than raw statistics. But the answer is none of them. The Yamato actually had a fairly shallow draft for a ship that size and while she turned quite nimbly, she gave up a lot of speed doing it, and the wind could blow her around given her massive size, but she did handle rough seas well. The KGV shipped water constantly, as a result of the admiralty wanting her lower front turret to be able to fire directly over the bow. That's why there is no rise on her bow. The Iowa shipped a ton of water as well and had less than stellar turning radius that was affected by her long slender design mentioned earlier. The Nelson lacked power to maneuver, turned poorly, and had a huge conning tower that acted like a sail that kept blowing her off her line, and she shipped plenty of water due to the firing over the bow retirements, but at least she handled well in rough water.

Winner: HMS Vanguard....had so slip in a ringer. Great sea boat with modern secondary, modern anti-aircraft, modern radars, good speed, great sea keeping, world war one era guns and finished at a point when the age of battleships was clearly over.

So....lot of worlds and lots of numbers...long story short (I late). The Iowa is the best all around battleship. But like heavy weight boxers, whoever lands the first big blow is probably going to win, or at least force the other guy to run away. The Iowa had the advantage of being able to pick when the battle would be fought, had a better chance of landing the first blow and the best change of getting away if things went poorly.

--- Rich

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