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Tuesday, August 02, 2005

The Ger/PG/1915 is more marginal in Springsharp than it should be

The Ger/PG/1915 design doesn't work as well in Springsharp as a real ship. The British S-class are a case in point. They were more heavily armed than this design, and were often faster. I imagine that they had a longer range, as well. The specifications were 900 tons (standard displacement, I believe), 280 tons of fuel oil, 36 knots, and 275ft long. In my wildest dreams, I hoped for 75,000 SHP, although the actual design was nominally 25,500 SHP. I think that I credited this ship with 3-5in QF guns, but this time, only 3-4in guns seemed reasonable. For 3-5in QF guns to work, I would have to reduce the speed to 35 knots. For the 3-5in QF and 36 knots to work, I would have to increase the displacement to 1,175 tons and the draft to a ridiculous 15ft. This is the Springsharp report for the 3-4in QF gun ship:
Ger/PG/1915, Germany Fast Gunboat laid down 1915 (Engine 1950)

Displacement:
 1,002 t light; 1,033 t standard; 1,090 t normal; 1,136 t full load

Dimensions: Length overall / water x beam x draught
 275.80 ft / 275.00 ft x 28.00 ft x 14.00 ft (normal load)
 84.06 m / 83.82 m x 8.53 m  x 4.27 m

Armament:
      3 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1915 Model
   Breech loading guns in deck mounts with hoists
   on centreline ends, majority forward, 1 raised mount
 Weight of broadside 96 lbs / 44 kg
 Shells per gun, main battery: 180

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 2 shafts, 48,176 shp / 35,939 Kw = 36.00 kts
 Range 1,800nm at 15.00 kts
 Bunker at max displacement = 103 tons

Complement:
 94 - 123

Cost:
 £0.192 million / $0.769 million

Distribution of weights at normal displacement:
 Armament: 12 tons, 1.1 %
 Machinery: 622 tons, 57.0 %
 Hull, fittings & equipment: 368 tons, 33.8 %
 Fuel, ammunition & stores: 88 tons, 8.1 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   236 lbs / 107 Kg = 7.4 x 4.0 " / 102 mm shells or 0.2 torpedoes
 Stability (Unstable if below 1.00): 1.26
 Metacentric height 1.1 ft / 0.3 m
 Roll period: 11.1 seconds
 Steadiness - As gun platform (Average = 50 %): 54 %
   - Recoil effect (Restricted arc if above 1.00): 0.36
 Seaboat quality  (Average = 1.00): 1.08

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.354
 Length to Beam Ratio: 9.82 : 1
 'Natural speed' for length: 16.58 kts
 Power going to wave formation at top speed: 73 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 2.00 degrees
 Stern overhang: 0.00 ft / 0.00 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  23.00 ft / 7.01 m
    - Forecastle (20 %): 21.00 ft / 6.40 m
    - Mid (36 %):  21.00 ft / 6.40 m (13.00 ft / 3.96 m aft of break)
    - Quarterdeck (15 %): 13.00 ft / 3.96 m
    - Stern:  13.00 ft / 3.96 m
    - Average freeboard: 16.04 ft / 4.89 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 192.5 %
  - Above water (accommodation/working, high = better): 141.7 %
 Waterplane Area: 4,673 Square feet or 434 Square metres
 Displacement factor (Displacement / loading): 45 %
 Structure weight / hull surface area: 28 lbs/sq ft or 138 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.38
  - Longitudinal: 6.24
  - Overall: 0.51
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent

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