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Friday, October 06, 2006

The HMS Unapproachable with coal-fired boilers

This is my attempt at the HMS Unapproachable design with 4-9.2in, 12-7.5in, and 12-4in QF guns, with coal-fired boilers. To make this work requires pretty lightweight machinery. The speed is agressive at 25.5 knots. The armour basis is 6in with a 2in deck. This is the photo of one of these ships:

This is the Springsharp report:
HMS Unapproachable, Great Britain Armoured Cruiser laid down 1905 (Engine 1910)

Displacement:
 14,696 t light; 15,454 t standard; 17,700 t normal; 19,497 t full load

Dimensions: Length overall / water x beam x draught
 554.00 ft / 554.00 ft x 75.00 ft x 26.50 ft (normal load)
 168.86 m / 168.86 m x 22.86 m  x 8.08 m

Armament:
      8 - 7.50" / 191 mm guns (4x2 guns), 210.94lbs / 95.68kg shells, 1905 Model
   Breech loading guns in turrets (on barbettes)
   on side ends, evenly spread
      4 - 9.20" / 234 mm guns (2x2 guns), 389.34lbs / 176.60kg shells, 1905 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread, all raised mounts
      4 - 7.50" / 191 mm guns in single mounts, 210.94lbs / 95.68kg shells, 1905 Model
   Breech loading guns in turrets (on barbettes)
   on side, evenly spread, all raised mounts
      12 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1905 Model
   Quick firing guns in deck mounts with hoists
   on side, evenly spread, all raised mounts
 Weight of broadside 4,473 lbs / 2,029 kg
 Shells per gun, main battery: 150

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 6.00" / 152 mm 390.00 ft / 118.87 m 16.00 ft / 4.88 m
 Ends: Unarmoured
   Main Belt covers 108 % of normal length

   - Torpedo Bulkhead:
  1.50" / 38 mm 390.00 ft / 118.87 m 26.00 ft / 7.92 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 8.00" / 203 mm 5.00" / 127 mm  8.00" / 203 mm
 2nd: 8.00" / 203 mm 5.00" / 127 mm  8.00" / 203 mm
 3rd: 8.00" / 203 mm 5.00" / 127 mm  8.00" / 203 mm
 4th: 4.00" / 102 mm 4.00" / 102 mm  4.00" / 102 mm

   - Armour deck: 2.00" / 51 mm, Conning tower: 8.00" / 203 mm

Machinery:
 Coal fired boilers, steam turbines, 
 Direct drive, 4 shafts, 52,957 shp / 39,506 Kw = 25.50 kts
 Range 5,400nm at 15.00 kts
 Bunker at max displacement = 4,043 tons (100% coal)

Complement:
 766 - 997

Cost:
 £1.321 million / $5.284 million

Distribution of weights at normal displacement:
 Armament: 559 tons, 3.2 %
 Armour: 5,258 tons, 29.7 %
    - Belts: 1,584 tons, 8.9 %
    - Torpedo bulkhead: 563 tons, 3.2 %
    - Armament: 1,908 tons, 10.8 %
    - Armour Deck: 1,086 tons, 6.1 %
    - Conning Tower: 117 tons, 0.7 %
 Machinery: 2,407 tons, 13.6 %
 Hull, fittings & equipment: 6,472 tons, 36.6 %
 Fuel, ammunition & stores: 3,004 tons, 17.0 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   25,021 lbs / 11,349 Kg = 118.6 x 7.5 " / 191 mm shells or 4.2 torpedoes
 Stability (Unstable if below 1.00): 1.02
 Metacentric height 3.4 ft / 1.0 m
 Roll period: 17.2 seconds
 Steadiness - As gun platform (Average = 50 %): 59 %
   - Recoil effect (Restricted arc if above 1.00): 0.64
 Seaboat quality  (Average = 1.00): 1.19

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.563
 Length to Beam Ratio: 7.39 : 1
 'Natural speed' for length: 23.54 kts
 Power going to wave formation at top speed: 53 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): -2.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  22.00 ft / 6.71 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: 20.16 ft / 6.14 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 94.7 %
  - Above water (accommodation/working, high = better): 145.9 %
 Waterplane Area: 29,343 Square feet or 2,726 Square metres
 Displacement factor (Displacement / loading): 122 %
 Structure weight / hull surface area: 145 lbs/sq ft or 708 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.97
  - Longitudinal: 1.62
  - Overall: 1.02
 Hull space for machinery, storage, compartmentation is adequate
 Room for accommodation and workspaces is excellent

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