If you're going to build a light capital ship that can't stand the line of battle with real battleships, all you're going to be able to do with it is fight off cruisers. Because you then have to optimize for the cruiser-killer role, you will have to accept less protection and torpedo defense in exchange for the speed you will need to hunt down cruisers. What else do you think these ships would be doing, and what makes do you think would pay for these instead of real battleships or more versatile cruisers, unless you create an arbitrary class of shops that basically don't exist outside of the British I-class cruisers.
You're looking too far in the past. The ships that would be canceled by a TTL Washington Treaty would be a generation or two after the Bayerns and Mackensens. We know that the Bayern follow-on was a fast superdreadnought comprable to Nagato and that the Mackensen follow-on was only a few knots faster. We don't know what would have come after that.
Why do you think that the Twins are a design to be replicated? All indications are that they're under performance, setting aside the more general problems with large German warships, was largely attributable to the small size of the guns. They may have been able to land hits at long range, but those hits couldn't reasonably put the hurt on anything bigger than a heavy cruiser. They would have had to get in close to hurt anything with heavy armor, and that was just too risky compared to other options.
It's easy to mission kill a warship without going through the armor. The float bubble only protects floatation. The action at Lofoten was fought in enormous weather, and the problems that the Twins encountered attempting to engage Renown, along with the damage inflicted by Renown's early hits to the superstructures, would have reasonably forced any battleship, regardless of size, to break off the action. It would have been foolhardy for Lutjens to risk his battleships in the face of the British destroyers in an attempt to come to grips with Renown.
Yes, they probably could have closed the range and taken down Renown, but what condition would they be in after that? A ship with bigger guns operating under similarly cautious orders could have engaged with effect from even farther out, which would have made withdrawal even easier if things got spicy. The Twins didn't have enough deck penetration to get to the good parts of Renown at any range (for an optically guided gunfight), and they could only get through her belt within about 20 kiloyards, or even closer if Renown was anything other than broadside to them
Ok, they close to close range of Renown and sink her. At least one of the ships is going to be in bad condition after that, assuming that they don't golden bb Renown. You now have one of your two capital ships badly damaged and easily within reach of the much larger RN, which knows you're going to return south and can pave those routes with every available submarine, not to mention aircraft and possibly it's own BB's and BC's. If one of the twins is sunk, that's 1/2 of your capital ships for 1/14 of the RN's capital ships. If I were the RN, I'd make that trade anytime.
Didn't exist at the time of the WNT, and it proves my point about small-gun capital ships.
They would have easily outgunned any of the Big Cats (Lion, Tiger, Kongos) between their superior fire control and super-heavy shells that put armor penetration on par with older 14-inch class guns. They were bigger and faster than the Cats and somewhat more heavily armored.
Alas they cost way too much for their capabilities and didn't have a TDS worthy of the name(which was done to cut down costs and construction time.) and whoever thought giving them a single rudder should have been shot.Still I'm sure Beatty would have given his right arm to replace his ships with them
Post-Jutland, 14-inch is the minimum size possibly acceptable, 15-inch is workable if you are compromising firepower for speed, and 16-inch is optimum.
The cats didn't have much of a TDS to their name, either. It only really became a big deal with American and French treaty battleships.
They were also four knots faster and had twice the installed horsepower.
The British battle scouts had trouble stopping German 11-inch and 12-inch. Nobody should expect them to stand up under that kind of fire for very long.
Belt armor had the same maximum thickness and higher average thickness, and the deck was more heavily armored.
This kind of ship is, at best, a second-line capital ship incapable of standing in the line of battle and, at worst, the kind of cruiser killer you claim you're trying to get away from. These stats match the Dunkerque, a ship designed expressly to counter German cruising raiders, which was 29.5 kts, 9 inch belt, 4.5 inch deck, 8 x 13 inch guns. Obviously, we can see how Dunkerque handled 15-inch shell fire at Mers-el-Kebir.
