They were also short ranged for supposed commerce raiding. According to
Wikipedia, Scharnhorst's max range was 7,100 nmi 19 knots, and even less for Gneisenau at 6,200 nmi. This is not useful endurance for commerce raiding where you want to disappear into the Atlantic or Indian Oceans to prey on moderately-defended convoys. Only the MTO-focused
Littorio class has lower endurance. For comparison on endurance of other pre-war battleship designs: KGV class 15,600 nmi at 10 knots; North Carolina class 17,450 nmi at 15 knots.
The Scharnhorsts need
reliable diesel-powered cruising engines combined with turbines for speed and a sizable fuel load, hotel services (food, water production, etc.), and efficient displacement and hull form to give them >18,000 nmi range at >12 knots. It's approx 11k nmi (38 days at 12 knots) from Kiel to Ceylon via the Cape of Good Hope. German or cooperative neutral supply ships can meet her in the Indian Ocean to top up.
Problem 1: Diesel engines (the 30s MAN ones) burn diesel. The boilers burn fuel oil. Neither may use the other fuel. How much of each to do you load into your CODAS ship? What happens if you get it wrong?? e.g. cruiser Karlsruhe could travel 18,000nm@10kts if all 1,350 tons were diesel, but max speed would be 10.5kts versus 7,200nm@17kts if all fuel oil. But range drops to only 2,760nm@15kts under wartime conditions*
Problem 2: Feathering propellers of 30s have a maximum capacity of ~12k hp. So, your high speed turbine propellers must be disconnected when cruising or the 'cold' blades will destroy the turbine. Similarly, the diesels must be disconnected before high speed running or they will be over rev'd and engine will be spitting rods. And the disconnecting/reconnecting needs to be done at slow speed e.g. <10kn. It also takes >20 minutes to disconnect the diesels/connect and warm up the turbines. So, during the war, ships are running only on turbines. (Scharnhorst and Gneisenau actually disconnected the outer shafts when cruising to improve efficiency and basically stopped to reconnect them. With a lot of praying that nothing bad comes over the horizon while its taking place).
*RN figures show similar drops in range when prepared for combat. Range numbers in Wiki are for peacetime, clean hulls, not war conditions/6 months out of dock in tropical water.
Scharnhorst class has a terrible gestation. Raeder ordered the 2 D class ships, hulls were laid down in Feb. '34.
Now when we understand ship construction and the project planning of same, we know that the laying down ceremony is a formality.
There are already 100s (1,000s) of tons of steel assembled, ready to install the day after the dignitaries have left and real work commences (there are photos of the bow section ready to be installed waiting slip side).
For 2 ships * 2 turrets * 3 guns/turret, plus a couple proof barrels need to be ready for when the trial assembly of the turret is done, after which it is disassembled, transported to the fitting out dock and assembled into the hull. And you want this all ready by the time the hull is launched (Plan was ~15 month build time from laying down to launch based on historic Scharnhorst). Knowing the guns were actually ordered in Nov. 33, and assuming Krupp can manufacture 1/month, the 12 barrels would be ready by Nov. '34, assembled in turrets and tested by Mar' 35 then disassembled and delivered pier side for the May, '35. By the Jun, '35 launch, the initial reassembly would be complete and they could be installed into the awaiting hull. The plan comes together on schedule
For the D class, there were 2 options - using 8 - 12 cylinder 42/58 diesels as in previous Panzerschiffe, which would provide 80k hp versus medium temperature/pressure boilers/turbines which would provide 125k hp. The extra ~50% power makes the ship ~3kts faster (32 vs 29kts). And the steam/turbine team was offering cruising turbines which would provide the same range as diesels. So, steam power was selected.
At the time, it wasn't considered that the 2 -12k hp cruising turbines would put ~25k load on the main turbines (Vulcan clutches work equally driven as driving/ cruising turbines must be kept from over-speeding aka braked) making the power difference much smaller. And during cruising, the main turbines needed some steam to keep them warm, so they don't eat themselves, so the range wasn't as good as predicted. As a result the historic Scharnhorst class ditches the cruising turbines and take 25% range hit of using main engines all the time.
KM also doesn't know getting fuel oil in WWII is going to be as problematic as steaming coal was in WWI.
Now, Raeder has been
campaigning coaxing Uncle Adolf for more firepower i.e. either 33cm or a 3rd turret in Panzerschiffe D, finally selling it on KM ship will have 9 guns to Dunkerque's 8 (RN campaigning for 12" main guns for future capital ships has make 33cm guns undesirable). So, Uncle Adolf asks a couple simple questions:
What is distance between superimposed turrets - based on ugly twins its 19m.
How much longer does the hull need to be for the 12 cylinder engine...well actually as the beam has increased by 4m and the auxiliary engines are 6M32/44 vs 5M42/58, the port and starboard powerplants fit side by side, not one in front of the other, so with the juggling of the electrical generation engines, the engine compartment is shorter! And should steam be chosen instead, the same power or more could be accommodated in this space.
But KM wants turrets not mounts and additional HAA, in the extra space so you can't shorten hull around powerplant compartment.
So, 181m for AGS + 19m = 200m; plan for Panzerschiffe D is 207m; AGS is 11k tons, Panzerschiffe D is 18k tons for 50% additional main armament; displacement seems inline. Uncle Adolf doesn't see any issue with 3 turrets and approves. (OK, there's doing to be slight delay to rearrange forward barbette(s) but the naval architect gets paid to fix that PDQ). **
Based on the above Raeder stops construction on the D class in July, '35, with the hull for Panzerschiffe D >40% complete, with another 20+% material worked/on order. Krupp has finished 8+ 28cm barrels with another couple in process and Deschimag/Brown Boleri have boilers ~50% complete. Krupp/Deschimag/Brown Boleri as private firms (and in Brown Boleri foreign country) have airtight contracts in place that they will deliver and be paid for what was ordered.
And the Panzerschiffe redesigned into Schlachtschiff (not really what was authorized) needing to reused as much of the material as possible - specifically the 28cm guns and the boilers/turbines. Increasing armour from 220m belt/70 mm deck to 320mm/105mm respectively causes the weight to grow from 18k tons to 26k tons. To maintain speed, a 3rd boiler/turbines set is added. This increase length from 207m to 231m, which adds weight, but worse, it means the keel must be deeper so the hull doesn't fold in 2. Which raises the boiler and the armoured deck over them. As the whole process is rushed - the ships being a 18 months behind original schedule - no one notices this has put a gap in the armour until it is too late (an Achilles heal worse than Hood; sort of similar to the mismatch between barbettes and turrets for Iowa class where everyone one wasn't communicating.).
So, if you're going to build additional Scharnhorst class and/or up gunned versions i.e. 3 x 2 - 38cm, there is going to be huge push from the design office to clean up the mess. And as a result they will be entirely different class.
Aside: 12 - 42/58 diesels (120k hp) would give just over 28kts based on the speed/power curve I have for Scharnhorst in Whitley German Capital ships; range would be roughly double as diesels are that efficient at cruise.
**It would have been interesting to see what a 3 turret Panzerschiffe D would have turned out like...probably as messed up the historic Scharnhorst class.
My 64 Reichsmarks question: We know Raeder was planning Panzerschiffe F (at least) under Versailles to be a treaty cruiser (8" guns/10k tons). How is Panzerschiffe D, even in original form, not superior?