Japanese Ship Designs 1918+

[Desertfox]

I believe you missed the news about the IJN standing up two cavalry divisions in Australia...

[Desertfox]

Looking towards the future, trying to figure out what to build next. The IJN currently has the following modern (1910+) fleet ships available:

4x 14" Battleships
2x 12" Battleships
4x 14" Battlecruisers
4x 12" Battlecruisers
1x 10" Heavy Cruiser
8x 5" Scout Cruisers
4x 6" Light Cruisers
3x Torpedo Cruisers
60x ~750t Destroyers
24x 1500t Destroyers

The capital ship force is reasonable for the Pacific and will have to wait till the new 16" guns are available before the next batch of fast battleships get started. No need there and there are plans in the works.

There is a distinct major hole as far as heavy cruisers. However, the Myoko class has begun construction, hole should be patched up as they begin entering service. Likely 8-12 planned.

There is another, less severe hole at light cruisers. The 5" cruisers are obsolete and will likely be refit and relegated to colonial gunboat duties. However, the Azula class will begin construction as well and should help patch that hole up, likely 12-20 planned, including aircraft carrying recon versions. An aircraft carrier design using the same hull is likely in the future as well.   

The destroyer force is in great shape as the Fubukis enter service with another batch of 24 likely to be built.

The current IJN is unbalanced but plans are underway to rectify those issues. No need for new designs at this time other than the 16" Amagi class in the near future. That frees up tonnage to build a variety of non-fleet combatants to replace the massive amount of old/foreign/obsolete ships currently in the IJN inventory. Near term that will include the following:
-A new minelayer to replace the slow Tokiwa and Suzuya classes and eventually the Yodos.
-A new liaison/training cruiser to replace the Chikumas and the Kongo.
-A batch of 48 Chidori class TBs to replace the Kamikaze/Umikaze/Sakura class DDs.
-A new fleet resupply auxiliary to support and eventually replace the Kobayashi Marus.
-A new class of oceangoing ASW frigates

[Desertfox]

New minelayer based on the Tenryu/Kuma hulls. Upgraded armament as found on the Fubukis. Japanese minelaying doctrine is primarily defensive and colonial in nature, so the slow speed is not an issue, and the guns allow it to serve as a colonial gunboat when not laying mines. Armor is splinter protection for the mines.

Nagara, Japan Minelayer laid down 1923

Displacement:
   1,501 t light; 1,565 t standard; 1,831 t normal; 2,044 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (342.64 ft / 340.00 ft) x 42.00 ft x (10.20 / 11.02 ft)
   (104.44 m / 103.63 m) x 12.80 m  x (3.11 / 3.36 m)

Armament:
      4 - 5.00" / 127 mm 50.0 cal guns - 66.16lbs / 30.01kg shells, 180 per gun
     Quick firing guns in deck and hoist mounts, 1923 Model
     2 x Single mounts on sides amidships
      8 - 1.00" / 25.4 mm 70.0 cal guns - 0.56lbs / 0.25kg shells, 300 per gun
     Machine guns in deck mounts, 1923 Model
     4 x Twin mounts on sides, evenly spread
      Weight of broadside 269 lbs / 122 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Ends:   Unarmoured
   Upper:   1.00" / 25 mm   100.00 ft / 30.48 m   5.00 ft / 1.52 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.00" / 25 mm         -         1.00" / 25 mm

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 11,664 shp / 8,701 Kw = 24.00 kts
   Range 6,200nm at 14.00 kts
   Bunker at max displacement = 479 tons

Complement:
   139 - 181

Cost:
   £0.395 million / $1.580 million

Distribution of weights at normal displacement:
   Armament: 81 tons, 4.4 %
      - Guns: 81 tons, 4.4 %
   Armour: 31 tons, 1.7 %
      - Belts: 25 tons, 1.4 %
      - Armament: 5 tons, 0.3 %
   Machinery: 390 tons, 21.3 %
   Hull, fittings & equipment: 621 tons, 33.9 %
   Fuel, ammunition & stores: 330 tons, 18.0 %
   Miscellaneous weights: 379 tons, 20.7 %
      - Hull above water: 300 tons
      - On freeboard deck: 44 tons
      - Above deck: 35 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     1,938 lbs / 879 Kg = 31.0 x 5.0 " / 127 mm shells or 0.8 torpedoes
   Stability (Unstable if below 1.00): 1.15
   Metacentric height 1.8 ft / 0.5 m
   Roll period: 13.2 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.17
   Seaboat quality  (Average = 1.00): 1.01

Hull form characteristics:
   Hull has raised forecastle,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.440 / 0.454
   Length to Beam Ratio: 8.10 : 1
   'Natural speed' for length: 18.44 kts
   Power going to wave formation at top speed: 54 %
   Trim (Max stability = 0, Max steadiness = 100): 70
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   30.00 %,  15.00 ft / 4.57 m,  15.00 ft / 4.57 m
      - Forward deck:   30.00 %,  9.00 ft / 2.74 m,  9.00 ft / 2.74 m
      - Aft deck:   25.00 %,  9.00 ft / 2.74 m,  9.00 ft / 2.74 m
      - Quarter deck:   15.00 %,  9.00 ft / 2.74 m,  9.00 ft / 2.74 m
      - Average freeboard:      10.80 ft / 3.29 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 101.8 %
      - Above water (accommodation/working, high = better): 111.4 %
   Waterplane Area: 9,036 Square feet or 839 Square metres
   Displacement factor (Displacement / loading): 125 %
   Structure weight / hull surface area: 52 lbs/sq ft or 256 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.88
      - Longitudinal: 1.13
      - Overall: 0.90
   Adequate machinery, storage, compartmentation space
   Adequate accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform

10t - Fire Control
25t - LR Wireless
24t - 6 x 21" Torpedo Tubes
20t - Observation balloon
300t - Mines

[Desertfox]

New liaison cruiser design to replace the Chikumas. Extensive accommodations and sensor suites. A couple will be built as training cruisers with a different misc weight loadout. Secondary mission of escort group flagships and colonial gunboats.

Zuko/Katori, Japan Liason Cruiser laid down 1923

Displacement:
   2,005 t light; 2,097 t standard; 2,650 t normal; 3,092 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (340.00 ft / 340.00 ft) x 44.00 ft x (12.40 / 13.95 ft)
   (103.63 m / 103.63 m) x 13.41 m  x (3.78 / 4.25 m)

Armament:
      4 - 6.00" / 152 mm 50.0 cal guns - 114.33lbs / 51.86kg shells, 150 per gun
     Quick firing guns in deck and hoist mounts, 1923 Model
     2 x Twin mounts on centreline, evenly spread
      1 - 3.00" / 76.2 mm 45.0 cal gun - 13.62lbs / 6.18kg shells, 150 per gun
     Anti-air gun in deck mount, 1923 Model
     1 x Single mount on centreline forward
      1 raised mount
      8 - 1.00" / 25.4 mm 45.0 cal guns - 0.50lbs / 0.23kg shells, 150 per gun
     Machine guns in deck mounts, 1923 Model
     4 x Twin mounts on sides, evenly spread
      Weight of broadside 475 lbs / 215 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   2.00" / 51 mm   1.00" / 25 mm      2.00" / 51 mm
   2nd:   1.00" / 25 mm         -               -

   - Protected deck - single deck:
   For and Aft decks: 1.00" / 25 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 15,185 shp / 11,328 Kw = 24.00 kts
   Range 10,400nm at 14.00 kts
   Bunker at max displacement = 995 tons

Complement:
   184 - 240

Cost:
   £0.554 million / $2.214 million

Distribution of weights at normal displacement:
   Armament: 112 tons, 4.2 %
      - Guns: 112 tons, 4.2 %
   Armour: 156 tons, 5.9 %
      - Armament: 20 tons, 0.7 %
      - Armour Deck: 137 tons, 5.2 %
   Machinery: 508 tons, 19.2 %
   Hull, fittings & equipment: 899 tons, 33.9 %
   Fuel, ammunition & stores: 646 tons, 24.4 %
   Miscellaneous weights: 330 tons, 12.5 %
      - On freeboard deck: 280 tons
      - Above deck: 50 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     4,046 lbs / 1,835 Kg = 37.5 x 6.0 " / 152 mm shells or 1.2 torpedoes
   Stability (Unstable if below 1.00): 1.16
   Metacentric height 1.9 ft / 0.6 m
   Roll period: 13.3 seconds
   Steadiness   - As gun platform (Average = 50 %): 72 %
         - Recoil effect (Restricted arc if above 1.00): 0.35
   Seaboat quality  (Average = 1.00): 1.21

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.500 / 0.519
   Length to Beam Ratio: 7.73 : 1
   'Natural speed' for length: 18.44 kts
   Power going to wave formation at top speed: 58 %
   Trim (Max stability = 0, Max steadiness = 100): 59
   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:   30.00 %,  20.00 ft / 6.10 m,  14.00 ft / 4.27 m
      - Forward deck:   30.00 %,  14.00 ft / 4.27 m,  14.00 ft / 4.27 m
      - Aft deck:   25.00 %,  14.00 ft / 4.27 m,  14.00 ft / 4.27 m
      - Quarter deck:   15.00 %,  14.00 ft / 4.27 m,  14.00 ft / 4.27 m
      - Average freeboard:      14.72 ft / 4.49 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 79.8 %
      - Above water (accommodation/working, high = better): 144.5 %
   Waterplane Area: 9,967 Square feet or 926 Square metres
   Displacement factor (Displacement / loading): 135 %
   Structure weight / hull surface area: 62 lbs/sq ft or 301 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.83
      - Longitudinal: 1.87
      - Overall: 0.90
   Excellent machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform
   Good seaboat, rides out heavy weather easily

50t - 2 x LR Wireless
15t - FC
25t - 6x21" TT
20t - Observation balloon
50t - Flagship/SIGINT Facilities
50t - Liaison Officer Accommodations
80t - 2x20t boats
25t - Radar
15t - ASW Gear

[Desertfox]

Mercantile-hull, multi-purpose, patrol boats.

Shimushu, Japan Oceanic Patrol Vessel laid down 1923

Displacement:
   798 t light; 820 t standard; 937 t normal; 1,030 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (242.47 ft / 240.00 ft) x 32.00 ft x (9.70 / 10.37 ft)
   (73.90 m / 73.15 m) x 9.75 m  x (2.96 / 3.16 m)

Armament:
      1 - 5.00" / 127 mm 45.0 cal gun - 63.03lbs / 28.59kg shells, 100 per gun
     Quick firing gun in deck mount, 1923 Model
     1 x Single mount on centreline forward
      2 - 1.00" / 25.4 mm 45.0 cal guns - 0.50lbs / 0.23kg shells, 300 per gun
     Machine guns in deck mount, 1923 Model
     1 x Twin mount on centreline, aft deck forward
      1 raised mount
      Weight of broadside 64 lbs / 29 kg

Machinery:
   Diesel Internal combustion generators,
   Electric motors, 2 shafts, 5,220 shp / 3,894 Kw = 21.00 kts
   Range 3,900nm (7,410nm) at 14.00 kts
   Bunker at max displacement = 209 tons

Complement:
   84 - 110

Cost:
   £0.161 million / $0.645 million

Distribution of weights at normal displacement:
   Armament: 11 tons, 1.2 %
      - Guns: 11 tons, 1.2 %
   Machinery: 174 tons, 18.6 %
   Hull, fittings & equipment: 318 tons, 34.0 %
   Fuel, ammunition & stores: 139 tons, 14.8 %
   Miscellaneous weights: 294 tons, 31.4 %
      - Hull below water: 94 tons
      - On freeboard deck: 175 tons
      - Above deck: 25 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     1,648 lbs / 748 Kg = 26.4 x 5.0 " / 127 mm shells or 0.9 torpedoes
   Stability (Unstable if below 1.00): 1.13
   Metacentric height 1.1 ft / 0.3 m
   Roll period: 12.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.07
   Seaboat quality  (Average = 1.00): 1.21

Hull form characteristics:
   Hull has rise forward of midbreak,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.440 / 0.452
   Length to Beam Ratio: 7.50 : 1
   'Natural speed' for length: 15.49 kts
   Power going to wave formation at top speed: 58 %
   Trim (Max stability = 0, Max steadiness = 100): 58
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   31.00 %,  14.00 ft / 4.27 m,  12.00 ft / 3.66 m
      - Forward deck:   35.00 %,  12.00 ft / 3.66 m,  12.00 ft / 3.66 m
      - Aft deck:   22.00 %,  7.00 ft / 2.13 m,  7.00 ft / 2.13 m
      - Quarter deck:   12.00 %,  7.00 ft / 2.13 m,  7.00 ft / 2.13 m
      - Average freeboard:      10.55 ft / 3.22 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 75.4 %
      - Above water (accommodation/working, high = better): 111.0 %
   Waterplane Area: 4,860 Square feet or 451 Square metres
   Displacement factor (Displacement / loading): 139 %
   Structure weight / hull surface area: 42 lbs/sq ft or 206 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.93
      - Longitudinal: 2.10
      - Overall: 1.01
   Excellent machinery, storage, compartmentation space
   Adequate accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform
   Good seaboat, rides out heavy weather easily

25t - LR Wireless
2t - FC
25t - Experimental Radar
25t - Enhanced Hydophone Kit
25t- Observation Balloon
25t - Extra facilities
25t - Minesweeping gear
8t - ASW Weapons
40t - 2 x 10t boats
94t - Diesel/Electric Drive