How about a coal-fired version of the Ger/CB/1905?

I am getting into using coal-fired boilers for ships. I tried a version of the 2002 sketch design for the Ger/CB/1905, and could make the design work with coal-fired boilers by increasing the displacement by a good bit. I also lowered the freeboard by a foot and tweaked the steadiness to get a roll period greater than 14 seconds. I also increased topweight by giving 7in turret faces, barbettes, and conning tower. For a ship with a 4in armour basis and 2in deck armour, the result is pretty good. This is the Springsharp report:

Ger/CB/1905 2002 version, Germany Battlecruiser laid down 1905 (Engine 1907)

Displacement:
    20,460 t light; 21,145 t standard; 24,400 t normal; 27,004 t full load

Dimensions: Length overall / water x beam x draught
    700.00 ft / 700.00 ft x 80.00 ft x 24.40 ft (normal load)
    213.36 m / 213.36 m x 24.38 m  x 7.44 m

Armament:
      4 - 12.00" / 305 mm guns (2x2 guns), 864.00lbs / 391.90kg shells, 1905 Model
      Breech loading guns in turrets (on barbettes)
      on centreline ends, evenly spread
      12 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1905 Model
      Quick firing guns in casemate mounts
      on side, all amidships
    Weight of broadside 3,840 lbs / 1,742 kg
    Shells per gun, main battery: 90

Armour:
   - Belts:        Width (max)    Length (avg)        Height (avg)
    Main:    4.00" / 102 mm    350.00 ft / 106.68 m    16.00 ft / 4.88 m
    Ends:    Unarmoured
      Main Belt covers 77 % of normal length
      Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
        1.50" / 38 mm    350.00 ft / 106.68 m    24.00 ft / 7.32 m

   - Gun armour:    Face (max)    Other gunhouse (avg)    Barbette/hoist (max)
    Main:    7.00" / 178 mm    5.00" / 127 mm        7.00" / 178 mm
    2nd:    4.00" / 102 mm    4.00" / 102 mm        4.00" / 102 mm

   - Armour deck: 2.00" / 51 mm, Conning tower: 7.00" / 178 mm

Machinery:
    Coal fired boilers, steam turbines,
    Direct drive, 4 shafts, 130,023 shp / 96,997 Kw = 31.00 kts
    Range 5,400nm at 15.00 kts
    Bunker at max displacement = 5,860 tons (100% coal)

Complement:
    975 - 1,268

Cost:
    £2.257 million / $9.028 million

Distribution of weights at normal displacement:
    Armament: 480 tons, 2.0 %
    Armour: 3,870 tons, 15.9 %
       - Belts: 996 tons, 4.1 %
       - Torpedo bulkhead: 466 tons, 1.9 %
       - Armament: 730 tons, 3.0 %
       - Armour Deck: 1,551 tons, 6.4 %
       - Conning Tower: 127 tons, 0.5 %
    Machinery: 8,126 tons, 33.3 %
    Hull, fittings & equipment: 7,984 tons, 32.7 %
    Fuel, ammunition & stores: 3,940 tons, 16.1 %
    Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
    Survivability (Non-critical penetrating hits needed to sink ship):
      19,407 lbs / 8,803 Kg = 22.5 x 12.0 " / 305 mm shells or 2.3 torpedoes
    Stability (Unstable if below 1.00): 1.29
    Metacentric height 5.7 ft / 1.7 m
    Roll period: 14.1 seconds
    Steadiness    - As gun platform (Average = 50 %): 80 %
            - Recoil effect (Restricted arc if above 1.00): 0.34
    Seaboat quality  (Average = 1.00): 1.20

Hull form characteristics:
    Hull has rise forward of midbreak
    Block coefficient: 0.625
    Length to Beam Ratio: 8.75 : 1
    'Natural speed' for length: 26.46 kts
    Power going to wave formation at top speed: 56 %
    Trim (Max stability = 0, Max steadiness = 100): 67
    Bow angle (Positive = bow angles forward): -1.00 degrees
    Stern overhang: -1.00 ft / -0.30 m
    Freeboard (% = measuring location as a percentage of overall length):
       - Stem:        32.00 ft / 9.75 m
       - Forecastle (20 %):    27.00 ft / 8.23 m
       - Mid (50 %):        27.00 ft / 8.23 m (19.00 ft / 5.79 m aft of break)
       - Quarterdeck (15 %):    19.00 ft / 5.79 m
       - Stern:        19.00 ft / 5.79 m
       - Average freeboard:    23.40 ft / 7.13 m

Ship space, strength and comments:
    Space    - Hull below water (magazines/engines, low = better): 163.6 %
        - Above water (accommodation/working, high = better): 185.8 %
    Waterplane Area: 41,922 Square feet or 3,895 Square metres
    Displacement factor (Displacement / loading): 102 %
    Structure weight / hull surface area: 129 lbs/sq ft or 629 Kg/sq metre
    Hull strength (Relative):
        - Cross-sectional: 0.98
        - Longitudinal: 1.14
        - Overall: 1.00
    Hull space for machinery, storage, compartmentation is cramped
    Room for accommodation and workspaces is excellent
    Ship has slow, easy roll, a good, steady gun platform
    Good seaboat, rides out heavy weather easily