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Tuesday, October 31, 2006

HMS Incomparable

I found a page with the specification for the HMS Incomparable design project on Bob Henneman's site. The basic concept was for a 1000ft-long ship with 6-20in guns and a good speed. I tried to implement that in Springsharp, but was not very successful for a number of reasons. One is that Springsharp would only give a speed of 29 knots for a little over 180,000 SHP. Another was the due to the shallow draft, I had to greatly increase the displacement, which only made the powering situation worse. This is the Springsharp report, for what it is worth:
HMS Incomparable, Great Britain Battlecruiser laid down 1916

Displacement:
 60,067 t light; 62,631 t standard; 66,500 t normal; 69,595 t full load

Dimensions: Length overall / water x beam x draught
 1,001.73 ft / 1,000.00 ft x 104.00 ft x 25.00 ft (normal load)
 305.33 m / 304.80 m x 31.70 m  x 7.62 m

Armament:
      6 - 20.00" / 508 mm guns (3x2 guns), 4,000.00lbs / 1,814.37kg shells, 1916 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, majority forward, 1 raised mount - superfiring
      9 - 4.00" / 102 mm guns (3x3 guns), 32.00lbs / 14.51kg shells, 1916 Model
   Quick firing guns in deck mounts with hoists
   on centreline ends, majority aft, 2 raised mounts - superfiring
      6 - 4.00" / 102 mm guns (2x3 guns), 32.00lbs / 14.51kg shells, 1916 Model
   Quick firing guns in deck mounts with hoists
   on centreline, all amidships, all raised mounts - superfiring
      4 - 3.00" / 76.2 mm guns in single mounts, 13.50lbs / 6.12kg shells, 1916 Model
   Anti-aircraft guns in deck mounts 
   on side, evenly spread, all raised mounts
 Weight of broadside 24,534 lbs / 11,128 kg
 Shells per gun, main battery: 90
 8 - 21.0" / 533.4 mm submerged torpedo tubes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 10.0" / 254 mm 620.00 ft / 188.98 m 8.00 ft / 2.44 m
 Ends: 5.00" / 127 mm 300.00 ft / 91.44 m 8.00 ft / 2.44 m
   80.00 ft / 24.38 m Unarmoured ends
 Upper: 7.00" / 178 mm 620.00 ft / 188.98 m 8.00 ft / 2.44 m
   Main Belt covers 95 % of normal length

   - Torpedo Bulkhead:
  2.00" / 51 mm 620.00 ft / 188.98 m 24.00 ft / 7.32 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 14.0" / 356 mm 9.00" / 229 mm  14.0" / 356 mm
 2nd: 4.00" / 102 mm 4.00" / 102 mm  4.00" / 102 mm
 3rd: 4.00" / 102 mm 4.00" / 102 mm  4.00" / 102 mm

   - Armour deck: 4.00" / 102 mm, Conning tower: 10.00" / 254 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 4 shafts, 183,292 shp / 136,736 Kw = 29.00 kts
 Range 6,500nm at 15.00 kts
 Bunker at max displacement = 6,965 tons

Complement:
 2,069 - 2,691

Cost:
 £9.220 million / $36.880 million

Distribution of weights at normal displacement:
 Armament: 3,067 tons, 4.6 %
 Armour: 16,804 tons, 25.3 %
    - Belts: 4,027 tons, 6.1 %
    - Torpedo bulkhead: 1,101 tons, 1.7 %
    - Armament: 4,058 tons, 6.1 %
    - Armour Deck: 7,264 tons, 10.9 %
    - Conning Tower: 354 tons, 0.5 %
 Machinery: 6,829 tons, 10.3 %
 Hull, fittings & equipment: 33,367 tons, 50.2 %
 Fuel, ammunition & stores: 6,433 tons, 9.7 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   108,217 lbs / 49,087 Kg = 27.1 x 20.0 " / 508 mm shells or 13.3 torpedoes
 Stability (Unstable if below 1.00): 1.16
 Metacentric height 7.0 ft / 2.1 m
 Roll period: 16.5 seconds
 Steadiness - As gun platform (Average = 50 %): 60 %
   - Recoil effect (Restricted arc if above 1.00): 0.93
 Seaboat quality  (Average = 1.00): 1.21

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.895
 Length to Beam Ratio: 9.62 : 1
 'Natural speed' for length: 31.62 kts
 Power going to wave formation at top speed: 45 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 3.00 degrees
 Stern overhang: -2.00 ft / -0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  33.00 ft / 10.06 m
    - Forecastle (20 %): 29.00 ft / 8.84 m
    - Mid (67 %):  29.00 ft / 8.84 m (21.00 ft / 6.40 m aft of break)
    - Quarterdeck (15 %): 21.00 ft / 6.40 m
    - Stern:  21.00 ft / 6.40 m
    - Average freeboard: 26.68 ft / 8.13 m
 Ship tends to be wet forward

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 87.4 %
  - Above water (accommodation/working, high = better): 242.1 %
 Waterplane Area: 98,168 Square feet or 9,120 Square metres
 Displacement factor (Displacement / loading): 121 %
 Structure weight / hull surface area: 260 lbs/sq ft or 1,271 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 1.33
  - Longitudinal: 0.91
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is adequate
 Room for accommodation and workspaces is excellent
 Good seaboat, rides out heavy weather easily

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