The Ger/CL/1915 design from September 2001

In my program to create new drawings for my German designs from the early 1970's, I drew one for the Ger/CL/1915 ship. This has three twin mounts with 2-6in guns. There is one forward and two aft, with one superfiring. Apparently, the 32 knot speed is the issue, along with the relatively small dimensions. I had to cut back on armor, increase draft and freeboard, and drastically increase displacement, as well as use very lightweight machinery. That indicates that the design was too ambitious. This is the Springsharp report:

Ger/CL/1915, Germany Light Cruiser laid down 1915 (Engine 1945)

Displacement:
 5,431 t light; 5,621 t standard; 6,250 t normal; 6,753 t full load

Dimensions: Length overall / water x beam x draught
 476.47 ft / 475.00 ft x 47.00 ft x 19.00 ft (normal load)
 145.23 m / 144.78 m x 14.33 m  x 5.79 m

Armament:
      6 - 6.00" / 152 mm guns (3x2 guns), 108.00lbs / 48.99kg shells, 1915 Model
   Quick firing guns in deck mounts with hoists
   on centreline ends, majority aft, 1 raised mount aft - superfiring
 Weight of broadside 648 lbs / 294 kg
 Shells per gun, main battery: 180
 4 - 23.6" / 599.44 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 3.00" / 76 mm 275.00 ft / 83.82 m 8.00 ft / 2.44 m
 Ends: 2.00" / 51 mm 200.00 ft / 60.96 m 8.00 ft / 2.44 m
 Upper: 4.00" / 102 mm 165.00 ft / 50.29 m 8.00 ft / 2.44 m
   Main Belt covers 89 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 3.00" / 76 mm 2.00" / 51 mm  4.00" / 102 mm

   - Armour deck: 2.00" / 51 mm, Conning tower: 4.00" / 102 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 70,082 shp / 52,281 Kw = 32.00 kts
 Range 4,750nm at 18.00 kts
 Bunker at max displacement = 1,132 tons

Complement:
 350 - 456

Cost:
 £0.736 million / $2.943 million

Distribution of weights at normal displacement:
 Armament: 81 tons, 1.3 %
 Armour: 1,297 tons, 20.7 %
    - Belts: 645 tons, 10.3 %
    - Torpedo bulkhead: 0 tons, 0.0 %
    - Armament: 65 tons, 1.0 %
    - Armour Deck: 558 tons, 8.9 %
    - Conning Tower: 29 tons, 0.5 %
 Machinery: 1,770 tons, 28.3 %
 Hull, fittings & equipment: 2,284 tons, 36.5 %
 Fuel, ammunition & stores: 819 tons, 13.1 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   7,118 lbs / 3,229 Kg = 65.9 x 6.0 " / 152 mm shells or 1.1 torpedoes
 Stability (Unstable if below 1.00): 1.16
 Metacentric height 2.1 ft / 0.7 m
 Roll period: 13.5 seconds
 Steadiness - As gun platform (Average = 50 %): 53 %
   - Recoil effect (Restricted arc if above 1.00): 0.36
 Seaboat quality  (Average = 1.00): 1.07

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.516
 Length to Beam Ratio: 10.11 : 1
 'Natural speed' for length: 21.79 kts
 Power going to wave formation at top speed: 62 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 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:  27.00 ft / 8.23 m
    - Forecastle (20 %): 24.00 ft / 7.32 m
    - Mid (33 %):  24.00 ft / 7.32 m (16.00 ft / 4.88 m aft of break)
    - Quarterdeck (15 %): 16.00 ft / 4.88 m
    - Stern:  16.00 ft / 4.88 m
    - Average freeboard: 18.88 ft / 5.75 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 102.4 %
  - Above water (accommodation/working, high = better): 122.0 %
 Waterplane Area: 15,090 Square feet or 1,402 Square metres
 Displacement factor (Displacement / loading): 114 %
 Structure weight / hull surface area: 80 lbs/sq ft or 393 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.92
  - Longitudinal: 2.15
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is adequate
 Room for accommodation and workspaces is excellent