Heavy Cruisers / Battlecruisers (重巡洋艦/巡洋戦艦)

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Asama Class (淺間型) Heavy Cruiser
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These were initially designed in late 1900 but were not laid down because the General Staff had determined auxiliary and smaller ships were more necessary. By the time resources had become available for laying down, several design revisions had come and gone. It was initially intended to be a direct counter to the American Brandywine class and the French Castillon and Beaugency classes cruisers.

However as revisions progressed, the design adopted the distinct Japanese tint of being slightly slower but much more heavier armored. The mission for the ships had evolved too; they were now regarded more as the fast wing of the main battle-line than a direct super-cruiser counter.

01 - Asama (淺間), laid down 1902
02 - Tokiwa (常盤), laid down 1902

Asama, Japan Heavy Cruiser laid down 1902 (Engine 1900)

Displacement:
   10,000 t light; 10,488 t standard; 11,150 t normal; 11,680 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (439.63 ft / 439.63 ft) x 57.74 ft x (27.89 / 28.93 ft)
   (134.00 m / 134.00 m) x 17.60 m  x (8.50 / 8.82 m)

Armament:
      6 - 9.84" / 250 mm 45.0 cal guns - 440.92lbs / 200.00kg shells, 100 per gun
     Breech loading guns in turret on barbette mounts, 1902 Model
     3 x Twin mounts on centreline, evenly spread
      12 - 5.98" / 152 mm 45.0 cal guns - 108.07lbs / 49.02kg shells, 150 per gun
     Quick firing guns in casemate mounts, 1902 Model
     12 x Single mounts on sides, evenly spread
      6 hull mounts in casemates- Limited use in heavy seas
      8 - 2.24" / 57.0 mm 40.0 cal guns - 5.42lbs / 2.46kg shells, 200 per gun
     Quick firing guns in deck mounts, 1902 Model
     8 x Single mounts on sides, evenly spread
      40 - 1.00" / 25.4 mm 35.0 cal guns - 0.46lbs / 0.21kg shells, 400 per gun
     Machine guns in deck mounts, 1902 Model
     10 x Quad mounts on sides, evenly spread
      40 - 0.43" / 11.0 mm 35.0 cal guns - 0.04lbs / 0.02kg shells, 800 per gun
     Breech loading guns in deck mounts, 1902 Model
     4 x 2 row decuple mounts on sides, evenly spread
      Weight of broadside 4,006 lbs / 1,817 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   9.06" / 230 mm   337.93 ft / 103.00 m   9.84 ft / 3.00 m
   Ends:   3.94" / 100 mm   101.71 ft / 31.00 m   9.02 ft / 2.75 m
   Upper:   3.94" / 100 mm   337.93 ft / 103.00 m   9.02 ft / 2.75 m
     Main Belt covers 118 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   9.84" / 250 mm   3.94" / 100 mm      4.92" / 125 mm
   2nd:   2.95" / 75 mm   1.97" / 50 mm      1.97" / 50 mm
   3rd:   0.39" / 10 mm         -               -
   4th:   0.20" / 5 mm         -               -

   - Protected deck - single deck:
   For and Aft decks: 1.97" / 50 mm
   Forecastle: 1.97" / 50 mm  Quarter deck: 1.97" / 50 mm

   - Conning towers: Forward 9.84" / 250 mm, Aft 0.00" / 0 mm

Machinery:
   Coal and oil fired boilers, complex reciprocating steam engines,
   Direct drive, 3 shafts, 20,017 ihp / 14,933 Kw = 21.00 kts
   Range 4,500nm at 10.00 kts
   Bunker at max displacement = 1,192 tons (90% coal)

Complement:
   542 - 705

Cost:
   £1.118 million / $4.474 million

Distribution of weights at normal displacement:
   Armament: 874 tons, 7.8 %
      - Guns: 874 tons, 7.8 %
   Armour: 3,153 tons, 28.3 %
      - Belts: 1,863 tons, 16.7 %
      - Armament: 533 tons, 4.8 %
      - Armour Deck: 651 tons, 5.8 %
      - Conning Tower: 106 tons, 0.9 %
   Machinery: 3,097 tons, 27.8 %
   Hull, fittings & equipment: 2,775 tons, 24.9 %
   Fuel, ammunition & stores: 1,150 tons, 10.3 %
   Miscellaneous weights: 102 tons, 0.9 %
      - Hull above water: 52 tons
      - On freeboard deck: 25 tons
      - Above deck: 25 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     7,453 lbs / 3,380 Kg = 15.6 x 9.8 " / 250 mm shells or 1.1 torpedoes
   Stability (Unstable if below 1.00): 1.15
   Metacentric height 2.9 ft / 0.9 m
   Roll period: 14.3 seconds
   Steadiness   - As gun platform (Average = 50 %): 71 %
         - Recoil effect (Restricted arc if above 1.00): 0.82
   Seaboat quality  (Average = 1.00): 1.51

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.551 / 0.557
   Length to Beam Ratio: 7.61 : 1
   'Natural speed' for length: 20.97 kts
   Power going to wave formation at top speed: 48 %
   Trim (Max stability = 0, Max steadiness = 100): 47
   Bow angle (Positive = bow angles forward): 0.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  17.39 ft / 5.30 m,  16.40 ft / 5.00 m
      - Forward deck:   30.00 %,  16.40 ft / 5.00 m,  16.40 ft / 5.00 m
      - Aft deck:   30.00 %,  16.40 ft / 5.00 m,  16.40 ft / 5.00 m
      - Quarter deck:   20.00 %,  16.40 ft / 5.00 m,  16.40 ft / 5.00 m
      - Average freeboard:      16.48 ft / 5.02 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 118.1 %
      - Above water (accommodation/working, high = better): 102.3 %
   Waterplane Area: 17,737 Square feet or 1,648 Square metres
   Displacement factor (Displacement / loading): 88 %
   Structure weight / hull surface area: 109 lbs/sq ft or 530 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.92
      - Longitudinal: 2.10
      - Overall: 1.00
   Cramped machinery, storage, compartmentation space
   Adequate accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform
   Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Hull above water: 52 tons
20t Flag facilities
32t Reserve
On freeboard deck: 25 tons
25t Reserve
Above Deck: 25 tons
25t Reserve

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Tsukaba Class (筑波) Battlecruiser
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By late 1904, it had become clear to the General Staff that foreign capital ships and cruisers outpaced almost every ship in the Japanese Navy. In the wake of the Anglo-American conflict, the General Staff had determined that as least a small portion of the battleline should be much speedier than it's opponents in order to force the enemy to slow down via maneuvering so the rest of the battleline could catch up.

The pursuit of speed lead to design schemes ranging from 18,000 tons and 25,000 tons with ABXY and ABQXY arrangements of the main battery. These were rejected due to cost and so the General Staff reluctantly reduced the armor of the ships to resist only up to cruiser caliber shells and dropped the X turret. The resulting design was only 12,500 tons and was finalized as the Tsukaba class battlecruisers.

The class was not considered entirely satisfactory as the IJN estimated that development of 356mm/40 and 305mm/45 guns would soon be completed. However, the lower cost of the ships would allow it to serve well as a stopgap.

01 - Tsukaba (筑波), laid down 1904
02 - Ikoma (生駒 ), laid down 1904

Tsukaba, Japanese Battlecruiser laid down 1904 (Engine 1905)

Displacement:
   12,500 t light; 13,126 t standard; 13,614 t normal; 14,005 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (475.72 ft / 475.72 ft) x 67.91 ft x (27.89 / 28.51 ft)
   (145.00 m / 145.00 m) x 20.70 m  x (8.50 / 8.69 m)

Armament:
      6 - 12.01" / 305 mm 40.0 cal guns - 850.98lbs / 386.00kg shells, 80 per gun
     Breech loading guns in turret on barbette mounts, 1904 Model
     3 x Twin mounts on centreline ends, majority forward
      1 raised mount - superfiring
      14 - 5.98" / 152 mm 45.0 cal guns - 108.07lbs / 49.02kg shells, 150 per gun
     Breech loading guns in casemate mounts, 1902 Model
     14 x Single mounts on sides, evenly spread
      6 hull mounts in casemates- Limited use in all but light seas
      Weight of broadside 6,619 lbs / 3,002 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   7.09" / 180 mm   475.72 ft / 145.00 m   9.84 ft / 3.00 m
     Main Belt covers 154 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   7.09" / 180 mm   2.56" / 65 mm      7.09" / 180 mm
   2nd:   3.94" / 100 mm         -               -

   - Armoured deck - multiple decks:
   For and Aft decks: 1.57" / 40 mm
   Forecastle: 1.57" / 40 mm  Quarter deck: 1.57" / 40 mm

   - Conning towers: Forward 7.09" / 180 mm, Aft 0.00" / 0 mm

Machinery:
   Coal and oil fired boilers, complex reciprocating steam engines,
   Direct drive, 4 shafts, 31,414 ihp / 23,435 Kw = 23.00 kts
   Range 3,000nm at 10.00 kts
   Bunker at max displacement = 879 tons (90% coal)

Complement:
   629 - 819

Cost:
   £1.553 million / $6.212 million

Distribution of weights at normal displacement:
   Armament: 1,012 tons, 7.4 %
      - Guns: 1,012 tons, 7.4 %
   Armour: 2,610 tons, 19.2 %
      - Belts: 1,228 tons, 9.0 %
      - Armament: 646 tons, 4.7 %
      - Armour Deck: 649 tons, 4.8 %
      - Conning Tower: 87 tons, 0.6 %
   Machinery: 4,508 tons, 33.1 %
   Hull, fittings & equipment: 4,070 tons, 29.9 %
   Fuel, ammunition & stores: 1,114 tons, 8.2 %
   Miscellaneous weights: 300 tons, 2.2 %
      - On freeboard deck: 300 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     5,850 lbs / 2,653 Kg = 6.8 x 12.0 " / 305 mm shells or 1.0 torpedoes
   Stability (Unstable if below 1.00): 1.09
   Metacentric height 3.3 ft / 1.0 m
   Roll period: 15.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.80
   Seaboat quality  (Average = 1.00): 1.01

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.529 / 0.532
   Length to Beam Ratio: 7.00 : 1
   'Natural speed' for length: 21.81 kts
   Power going to wave formation at top speed: 51 %
   Trim (Max stability = 0, Max steadiness = 100): 69
   Bow angle (Positive = bow angles forward): 0.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  13.12 ft / 4.00 m,  13.12 ft / 4.00 m
      - Forward deck:   30.00 %,  13.12 ft / 4.00 m,  13.12 ft / 4.00 m
      - Aft deck:   35.00 %,  13.12 ft / 4.00 m,  13.12 ft / 4.00 m
      - Quarter deck:   15.00 %,  13.12 ft / 4.00 m,  13.12 ft / 4.00 m
      - Average freeboard:      13.12 ft / 4.00 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 139.4 %
      - Above water (accommodation/working, high = better): 87.9 %
   Waterplane Area: 22,106 Square feet or 2,054 Square metres
   Displacement factor (Displacement / loading): 82 %
   Structure weight / hull surface area: 136 lbs/sq ft or 664 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.94
      - Longitudinal: 1.65
      - Overall: 1.00
   Cramped machinery, storage, compartmentation space
   Cramped accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform

On freeboard deck: 300 tons
275t Reserve
  25t Long-Range Wireless