The Ger/CM/1915 design study

This is the middle member of the family of fast German minelayers. This ship now carries 360 mines at 38.5 knots. The ship has 3-5in guns with one superfiring, forward. The mines are carried on rails at the stern. This is the Springsharp report:

Ger/CM/1915, Germany Cruiser Minelayer laid down 1915 (Engine 1950)

Displacement:
 3,238 t light; 3,327 t standard; 3,606 t normal; 3,830 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
 (453.37 ft / 450.00 ft) x 44.00 ft x (17.00 / 17.63 ft)
 (138.19 m / 137.16 m) x 13.41 m  x (5.18 / 5.37 m)

Armament:
      3 - 5.00" / 127 mm 45.0 cal guns - 65.00lbs / 29.48kg shells, 150 per gun
   Quick firing guns in deck and hoist mounts, 1915 Model
   3 x Single mounts on centreline ends, majority forward
  1 raised mount - superfiring
      Weight of broadside 195 lbs / 88 kg

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

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 2 shafts, 84,825 shp / 63,279 Kw = 38.50 kts
 Range 4,200nm at 15.00 kts
 Bunker at max displacement = 503 tons

Complement:
 232 - 302

Cost:
 £0.578 million / $2.310 million

Distribution of weights at normal displacement:
 Armament: 51 tons, 1.4 %
 Armour: 45 tons, 1.3 %
    - Armament: 45 tons, 1.3 %
 Machinery: 1,898 tons, 52.6 %
 Hull, fittings & equipment: 933 tons, 25.9 %
 Fuel, ammunition & stores: 368 tons, 10.2 %
 Miscellaneous weights: 311 tons, 8.6 %
    - On freeboard deck: 311 tons

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   925 lbs / 420 Kg = 14.8 x 5.0 " / 127 mm shells or 0.4 torpedoes
 Stability (Unstable if below 1.00): 1.16
 Metacentric height 1.9 ft / 0.6 m
 Roll period: 13.3 seconds
 Steadiness - As gun platform (Average = 50 %): 58 %
   - Recoil effect (Restricted arc if above 1.00): 0.17
 Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
 Hull has a flush deck,
   a normal bow and large transom stern
 Block coefficient (normal/deep): 0.375 / 0.384
 Length to Beam Ratio: 10.23 : 1
 'Natural speed' for length: 24.59 kts
 Power going to wave formation at top speed: 67 %
 Trim (Max stability = 0, Max steadiness = 100): 57
 Bow angle (Positive = bow angles forward): 8.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = length of deck as a percentage of waterline length):
    Fore end,  Aft end
    - Forecastle: 25.00 %,  24.00 ft / 7.32 m,  21.00 ft / 6.40 m
    - Forward deck: 25.00 %,  21.00 ft / 6.40 m,  18.00 ft / 5.49 m
    - Aft deck: 35.00 %,  18.00 ft / 5.49 m,  16.00 ft / 4.88 m
    - Quarter deck: 15.00 %,  16.00 ft / 4.88 m,  16.00 ft / 4.88 m
    - Average freeboard:  18.78 ft / 5.72 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 174.6 %
  - Above water (accommodation/working, high = better): 184.4 %
 Waterplane Area: 12,450 Square feet or 1,157 Square metres
 Displacement factor (Displacement / loading): 79 %
 Structure weight / hull surface area: 40 lbs/sq ft or 193 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.46
  - Longitudinal: 1.75
  - Overall: 0.52
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent