I had some unrealistic ideas in 1971 and 1972

I had been interested in very fast destroyer and cruiser minelayers, back in the early 1970's. The problem is that I had a very little idea about what power was required and what strength and hull volume were required for such performance. The high end of the spectrum was a cruiser minelayer, 625ft long. There were two gun mounts forward and a large number of mines, aft. The hull was flush-decked and there were two wide funnels, with pole masts. There were very few characteristics specified, so I experimented, in Springsharp, with one possibility. The results were pretty disappointing. With the lightest weight machinery possible, I was only able to obtain 37 knots:

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

Displacement:
 7,789 t light; 7,987 t standard; 8,450 t normal; 8,821 t full load

Dimensions: Length overall / water x beam x draught
 629.75 ft / 625.00 ft x 58.00 ft x 18.00 ft (normal load)
 191.95 m / 190.50 m x 17.68 m  x 5.49 m

Armament:
      4 - 6.00" / 152 mm guns (2x2 guns), 108.00lbs / 48.99kg shells, 1915 Model
   Breech loading guns in deck mounts with hoists
   on centreline, all forward, 1 raised mount - superfiring
 Weight of broadside 432 lbs / 196 kg
 Shells per gun, main battery: 120

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

   - Armour deck: 1.00" / 25 mm, Conning tower: 1.00" / 25 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 129,717 shp / 96,769 Kw = 37.00 kts
 Range 4,500nm at 15.00 kts
 Bunker at max displacement = 834 tons

Complement:
 439 - 572

Cost:
 £1.094 million / $4.378 million

Distribution of weights at normal displacement:
 Armament: 54 tons, 0.6 %
 Armour: 474 tons, 5.6 %
    - Belts: 0 tons, 0.0 %
    - Torpedo bulkhead: 0 tons, 0.0 %
    - Armament: 36 tons, 0.4 %
    - Armour Deck: 429 tons, 5.1 %
    - Conning Tower: 9 tons, 0.1 %
 Machinery: 3,103 tons, 36.7 %
 Hull, fittings & equipment: 3,677 tons, 43.5 %
 Fuel, ammunition & stores: 661 tons, 7.8 %
 Miscellaneous weights: 480 tons, 5.7 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   7,343 lbs / 3,331 Kg = 68.0 x 6.0 " / 152 mm shells or 1.1 torpedoes
 Stability (Unstable if below 1.00): 1.24
 Metacentric height 3.2 ft / 1.0 m
 Roll period: 13.5 seconds
 Steadiness - As gun platform (Average = 50 %): 57 %
   - Recoil effect (Restricted arc if above 1.00): 0.14
 Seaboat quality  (Average = 1.00): 1.13

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.453
 Length to Beam Ratio: 10.78 : 1
 'Natural speed' for length: 25.00 kts
 Power going to wave formation at top speed: 59 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 4.00 degrees
 Stern overhang: 3.00 ft / 0.91 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  25.00 ft / 7.62 m
    - Forecastle (20 %): 21.00 ft / 6.40 m
    - Mid (50 %):  21.00 ft / 6.40 m
    - Quarterdeck (15 %): 21.00 ft / 6.40 m
    - Stern:  21.00 ft / 6.40 m
    - Average freeboard: 21.32 ft / 6.50 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 130.1 %
  - Above water (accommodation/working, high = better): 211.2 %
 Waterplane Area: 23,185 Square feet or 2,154 Square metres
 Displacement factor (Displacement / loading): 111 %
 Structure weight / hull surface area: 93 lbs/sq ft or 456 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.95
  - Longitudinal: 1.59
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent