The Ger/BB/1915 CDV Design

In the early 1970's, I was interested in coast defense battleships. I was familiar with what had been done in the pre-Dreadnought age, and thought that something good could be done, circa 1915. I have implemented a Springsharp design that is trying to be as faithful to my original intent, as possible. In particular, I wanted the weights to be close to what I had originally specified. I found, though, that I had underestimated the required hull weight to achieve adequate strength. The armor had to be reduced, accordingly, to stay close to the desired displacement. The ship has 4-1in BLR and 20-5in QF guns in twin mounts. The hull is flush-decked and there is a single funnel. The desired speed is modest, being just 20 knots. This is the Sprinsharp report:

Ger/BB/1915 CDV, Germany Coast Defense Battleship laid down 1915 (Engine 1937)

Displacement:
 26,621 t light; 28,308 t standard; 29,500 t normal; 30,453 t full load

Dimensions: Length overall / water x beam x draught
 585.40 ft / 585.00 ft x 100.00 ft x 24.10 ft (normal load)
 178.43 m / 178.31 m x 30.48 m  x 7.35 m

Armament:
      4 - 18.00" / 457 mm guns (2x2 guns), 2,916.00lbs / 1,322.68kg shells, 1915 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread
      20 - 5.00" / 127 mm guns (10x2 guns), 62.50lbs / 28.35kg shells, 1915 Model
   Quick firing guns in turrets (on barbettes)
   on side, all amidships, 4 raised mounts - superfiring
 Weight of broadside 12,914 lbs / 5,858 kg
 Shells per gun, main battery: 150

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 14.0" / 356 mm 360.00 ft / 109.73 m 8.00 ft / 2.44 m
 Ends: Unarmoured
 Upper: 10.0" / 254 mm 360.00 ft / 109.73 m 8.00 ft / 2.44 m
   Main Belt covers 95 % of normal length

   - Torpedo Bulkhead:
  5.00" / 127 mm 360.00 ft / 109.73 m 23.00 ft / 7.01 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 14.0" / 356 mm 9.00" / 229 mm  14.0" / 356 mm
 2nd: 5.00" / 127 mm 5.00" / 127 mm  5.00" / 127 mm

   - Armour deck: 6.00" / 152 mm, Conning tower: 14.00" / 356 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 31,015 shp / 23,137 Kw = 20.00 kts
 Range 4,500nm at 15.00 kts
 Bunker at max displacement = 2,145 tons

Complement:
 1,125 - 1,463

Cost:
 £3.503 million / $14.011 million

Distribution of weights at normal displacement:
 Armament: 1,614 tons, 5.5 %
 Armour: 12,926 tons, 43.8 %
    - Belts: 3,126 tons, 10.6 %
    - Torpedo bulkhead: 1,532 tons, 5.2 %
    - Armament: 2,625 tons, 8.9 %
    - Armour Deck: 5,356 tons, 18.2 %
    - Conning Tower: 288 tons, 1.0 %
 Machinery: 860 tons, 2.9 %
 Hull, fittings & equipment: 11,222 tons, 38.0 %
 Fuel, ammunition & stores: 2,879 tons, 9.8 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   59,120 lbs / 26,817 Kg = 20.3 x 18.0 " / 457 mm shells or 13.0 torpedoes
 Stability (Unstable if below 1.00): 1.19
 Metacentric height 6.9 ft / 2.1 m
 Roll period: 16.0 seconds
 Steadiness - As gun platform (Average = 50 %): 77 %
   - Recoil effect (Restricted arc if above 1.00): 0.55
 Seaboat quality  (Average = 1.00): 1.53

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.732
 Length to Beam Ratio: 5.85 : 1
 'Natural speed' for length: 24.19 kts
 Power going to wave formation at top speed: 44 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 1.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  23.00 ft / 7.01 m
    - Forecastle (20 %): 20.00 ft / 6.10 m
    - Mid (50 %):  20.00 ft / 6.10 m
    - Quarterdeck (15 %): 20.00 ft / 6.10 m
    - Stern:  20.00 ft / 6.10 m
    - Average freeboard: 20.24 ft / 6.17 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 65.8 %
  - Above water (accommodation/working, high = better): 163.4 %
 Waterplane Area: 48,248 Square feet or 4,482 Square metres
 Displacement factor (Displacement / loading): 107 %
 Structure weight / hull surface area: 181 lbs/sq ft or 885 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.55
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is excellent
 Room for accommodation and workspaces is excellent
 Ship has slow, easy roll, a good, steady gun platform
 Excellent seaboat, comfortable, can fire her guns in the heaviest weather