Japanese Ship Designs 1912+

[Desertfox]

Light cruiser with a heavier main battery in Furutaka-layout. Four planned: Furutaka, Kako, Aoba, Kinugasa.

Furutaka class, Japan Light Cruiser laid down 1913

Displacement:
   3,105 t light; 3,239 t standard; 3,683 t normal; 4,038 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (420.00 ft / 420.00 ft) x 45.00 ft x (15.50 / 16.54 ft)
   (128.02 m / 128.02 m) x 13.72 m  x (4.72 / 5.04 m)

Armament:
      6 - 6.00" / 152 mm 45.0 cal guns - 108.92lbs / 49.41kg shells, 150 per gun
     Quick firing guns in deck and hoist mounts, 1913 Model
     6 x Single mounts on centreline, evenly spread
      12 - 2.00" / 50.8 mm 45.0 cal guns - 4.03lbs / 1.83kg shells, 200 per gun
     Quick firing guns in deck mounts, 1913 Model
     4 x Triple mounts on sides, evenly spread
      Weight of broadside 702 lbs / 318 kg

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

   - Armoured deck - single deck:
   For and Aft decks: 0.50" / 13 mm

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 39,731 shp / 29,639 Kw = 30.00 kts
   Range 5,100nm at 14.00 kts
   Bunker at max displacement = 799 tons

Complement:
   236 - 307

Cost:
   £0.423 million / $1.694 million

Distribution of weights at normal displacement:
   Armament: 182 tons, 4.9 %
      - Guns: 182 tons, 4.9 %
   Armour: 88 tons, 2.4 %
      - Armament: 18 tons, 0.5 %
      - Armour Deck: 70 tons, 1.9 %
   Machinery: 1,536 tons, 41.7 %
   Hull, fittings & equipment: 1,234 tons, 33.5 %
   Fuel, ammunition & stores: 578 tons, 15.7 %
   Miscellaneous weights: 65 tons, 1.8 %
      - On freeboard deck: 45 tons
      - Above deck: 20 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     1,885 lbs / 855 Kg = 17.5 x 6.0 " / 152 mm shells or 0.6 torpedoes
   Stability (Unstable if below 1.00): 1.19
   Metacentric height 2.1 ft / 0.6 m
   Roll period: 13.1 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.45
   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): 0.440 / 0.452
   Length to Beam Ratio: 9.33 : 1
   'Natural speed' for length: 20.49 kts
   Power going to wave formation at top speed: 60 %
   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:   40.00 %,  17.00 ft / 5.18 m,  15.00 ft / 4.57 m
      - Forward deck:   30.00 %,  15.00 ft / 4.57 m,  15.00 ft / 4.57 m
      - Aft deck:   15.00 %,  15.00 ft / 4.57 m,  15.00 ft / 4.57 m
      - Quarter deck:   15.00 %,  15.00 ft / 4.57 m,  15.00 ft / 4.57 m
      - Average freeboard:      15.32 ft / 4.67 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 151.1 %
      - Above water (accommodation/working, high = better): 144.8 %
   Waterplane Area: 11,959 Square feet or 1,111 Square metres
   Displacement factor (Displacement / loading): 95 %
   Structure weight / hull surface area: 67 lbs/sq ft or 329 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.84
      - Longitudinal: 1.58
      - Overall: 0.90
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform

20t - 1908 Fire Control
25t - Long-range wireless
20t - 8 x 18" Torpedo Tubes

[Desertfox]

This replaces the "Mogami-class raider" previously seen in this thread. This is a multi-purpose littoral combatant. It can be deployed as a raider with enough supplies to self-deploy, used as a minelayer with up to 140 mines, can carry marines and landing craft as a fast transport, or fitted out with an observation balloon and used as a fleet scout. Primarily, these are to be used as colonial gunboats, with partial self-deploy (70t), a small marine contingent (40t), a small minelaying capability (20t), and a stationary-only observation balloon (10t). 

Tenryu, Japan Littoral Combatant  laid down 1912

Displacement:
   1,400 t light; 1,460 t standard; 1,795 t normal; 2,063 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (342.64 ft / 340.00 ft) x 42.00 ft x (10.00 / 11.04 ft)
   (104.44 m / 103.63 m) x 12.80 m  x (3.05 / 3.36 m)

Armament:
      5 - 5.00" / 127 mm 45.0 cal guns - 63.03lbs / 28.59kg shells, 140 per gun
     Quick firing guns in deck and hoist mounts, 1912 Model
     3 x Single mounts on centreline ends, majority aft
      1 raised mount aft - superfiring
     2 x Single mounts on sides amidships
      Weight of broadside 315 lbs / 143 kg

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

Machinery:
   Coal and oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 11,530 shp / 8,601 Kw = 24.00 kts
   Range 5,000nm at 14.00 kts
   Bunker at max displacement = 603 tons (40% coal)

Complement:
   137 - 179

Cost:
   £0.146 million / $0.583 million

Distribution of weights at normal displacement:
   Armament: 85 tons, 4.7 %
      - Guns: 85 tons, 4.7 %
   Armour: 13 tons, 0.7 %
      - Armament: 13 tons, 0.7 %
   Machinery: 477 tons, 26.6 %
   Hull, fittings & equipment: 629 tons, 35.0 %
   Fuel, ammunition & stores: 396 tons, 22.0 %
   Miscellaneous weights: 195 tons, 10.9 %
      - Hull above water: 140 tons
      - On freeboard deck: 20 tons
      - Above deck: 35 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     1,687 lbs / 765 Kg = 27.0 x 5.0 " / 127 mm shells or 0.7 torpedoes
   Stability (Unstable if below 1.00): 1.24
   Metacentric height 2.0 ft / 0.6 m
   Roll period: 12.5 seconds
   Steadiness   - As gun platform (Average = 50 %): 71 %
         - Recoil effect (Restricted arc if above 1.00): 0.22
   Seaboat quality  (Average = 1.00): 1.05

Hull form characteristics:
   Hull has raised forecastle,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.440 / 0.458
   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): 68
   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:   40.00 %,  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:   15.00 %,  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:      11.40 ft / 3.47 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 110.2 %
      - Above water (accommodation/working, high = better): 113.1 %
   Waterplane Area: 9,036 Square feet or 839 Square metres
   Displacement factor (Displacement / loading): 124 %
   Structure weight / hull surface area: 53 lbs/sq ft or 257 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.87
      - Longitudinal: 1.18
      - Overall: 0.90
   Adequate machinery, storage, compartmentation space
   Adequate accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform

10t - 1908 Fire Control
25t - LR Wireless
10t - 4 x 18" Torpedo Tubes
10t - Mine-sweeping Gear
140t - Mines/Supplies/Marines/Observation Balloon etc

[snip]

No waterline protection at all on the Furutaka and with an armored deck is a interesting design choice. Cant say I'm a fan of the armament layout, your fire arcs severely limit how many guns you can use in a case or pursuit. I like the hull and how quick it is. What about reducing the guns on her and adding some additional protection?

[Desertfox]

Armor is useless if you can't hurt the enemy (Sumas vs Chinese cruisers). Looking at my 2 year plan, the first two might get delayed to 1914, and the next two could get the Aoba gun layout, fixing the guns available for chase issue.

[Desertfox]

The Japanese two-year plan:

2 x Kawachi class Battleships
2 x Maya class Battlecruisers
2 x Furutaka class Protected Cruisers*
4 x Tenryu class Colonial Cruisers
2 x Surabaya class Colonial Gunboats*
4-8 x Kaibokan class Scouts
6-18 x Misc Destroyers
10-20 x No1 Class Minesweepers
25-50 x 1905 MTBs
5 x 1900 Submarines

*The protected cruisers and colonial gunboats are most at risk for being delayed by the war.

[Kaiser Kirk]

Armor is useless if you can't hurt the enemy (Sumas vs Chinese cruisers). Looking at my 2 year plan, the first two might get delayed to 1914, and the next two could get the Aoba gun layout, fixing the guns available for chase issue.

As a technical note, "armor decks" are generally fitted a deck level above the waterline, and meet the top of the belt.
A "armor deck" without a belt simply meets the side of the hull, and  shells can pass between the waterline and deck.
A "protective deck" would be fitted at or just above the waterline, with sides descending below it.

Also, 13mm is so thin it - according to the numbers in the Gun Research- would only stop splinters from 78mm and below.
So I think that deck is a waste of tonnage.

as another observation, while a destroyer-sized hull may have good seakeeping and habitability, that is relative to other destroyer sized hulls.

[Desertfox]

Yeah that should be a protected deck mainly for splinters. I'm still not in love with the Furutakas, so thats another reason they might be pushed back.

The Tenryus are light but not exactly small, their hulls are about the same size as the Parthian sailing frigates. They just have a very low draft to allow them to operate in shallow coastal waters that other ships can't.

[Kaiser Kirk]

you can keep it as a protective deck vs. splinters, just be advised that shells over ~78mm will send splinters right through it. Which means the 90mm Chinese Destroyers.

As for ship size.
Lx B is indeed similar.. though yours at 0.44 BC and mine at 0.636 are different.
But beyond that -
It's actually quite a lot smaller internally than my frigates.

If you consider BC is the proportion of a LxB rectangle,
Then the height would be draft to weather deck. 

So BC x L x B x draft+Weather deck

Parthia : 0.636x100x13x (4+3.86) =6498
Japan : 0.440 x103x12.8 x (2.7+3.05) = 3358

So while your LxB is indeed similar, your BC is smaller, and what in Mercantile would be GRT is smaller... by close to half.

So the original observation- that it's roomy for a destroyer sized vessel - stands.

[eltf177]

   Hull strength (Relative):
      - Cross-sectional: 0.84
      - Longitudinal: 1.58
      - Overall: 0.90

I'm surprised the "hull strained in all but light seas" warning isn't on.

[The Rock Doctor]

I thought Furutaka had two raised mounts?

[Desertfox]

That it did... I ran the numbers and I can't afford them anyways until 1915. So both the Furutakas and the Surabayas are being shelved for the time being.

[Desertfox]

So this is the ship that sparked the Petrol Motor-Electric Drive question, until I realized it was a moot point since you can't increase bunkerage in a refurbishment, so going with an electric drive is the best option.

Basically, Japan is looking into buying the Magallanes class gunboats from Iberia and refurbishing them for colonial use. Changes would be improved engines, Japanese armament, and adding wireless, fire control, and mine-sweeping gear. Cost would be 0.1 BP and $0.25 per ship. No savings in $ (especially with having to pay Iberia for the ships) but savings in BP which Japan is short off, and in time getting these ships into service.


Magallanes class, Iberia/Japan Gunboat laid down 1894 (Engine 1913)

Displacement:
   251 t light; 274 t standard; 281 t normal; 287 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (176.77 ft / 175.20 ft) x 23.62 ft x (6.24 / 6.32 ft)
   (53.88 m / 53.40 m) x 7.20 m  x (1.90 / 1.93 m)

Armament:
      2 - 5.00" / 127 mm 45.0 cal guns - 63.03lbs / 28.59kg shells, 170 per gun
     Quick firing guns in deck mounts, 1894 Model
     2 x Single mounts on centreline ends, evenly spread
      12 - 2.00" / 50.8 mm 45.0 cal guns - 4.03lbs / 1.83kg shells, 200 per gun
     Breech loading guns in deck mounts, 1894 Model
     4 x Single mounts on centreline ends, evenly spread
      Weight of broadside 174 lbs / 79 kg

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

Machinery:
   Petrol Internal combustion generators,
   Electric motors, 1 shaft, 1,169 ihp / 872 Kw = 17.00 kts
   Range 610nm at 10.00 kts
   Bunker at max displacement = 13 tons

Complement:
   33 - 44

Cost:
   £0.025 million / $0.101 million

Distribution of weights at normal displacement:
   Armament: 31 tons, 11.1 %
      - Guns: 31 tons, 11.1 %
   Armour: 5 tons, 1.8 %
      - Armament: 5 tons, 1.8 %
   Machinery: 55 tons, 19.7 %
   Hull, fittings & equipment: 123 tons, 43.6 %
   Fuel, ammunition & stores: 30 tons, 10.6 %
   Miscellaneous weights: 37 tons, 13.2 %
      - Hull below water: 14 tons
      - On freeboard deck: 20 tons
      - Above deck: 3 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     410 lbs / 186 Kg = 6.6 x 5.0 " / 127 mm shells or 0.4 torpedoes
   Stability (Unstable if below 1.00): 1.24
   Metacentric height 0.8 ft / 0.3 m
   Roll period: 10.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.43
   Seaboat quality  (Average = 1.00): 1.33

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.381 / 0.384
   Length to Beam Ratio: 7.42 : 1
   'Natural speed' for length: 13.24 kts
   Power going to wave formation at top speed: 52 %
   Trim (Max stability = 0, Max steadiness = 100): 53
   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:   20.00 %,  8.90 ft / 2.71 m,  7.20 ft / 2.19 m
      - Forward deck:   30.00 %,  7.20 ft / 2.19 m,  7.20 ft / 2.19 m
      - Aft deck:   35.00 %,  7.20 ft / 2.19 m,  7.20 ft / 2.19 m
      - Quarter deck:   15.00 %,  7.20 ft / 2.19 m,  7.20 ft / 2.19 m
      - Average freeboard:      7.34 ft / 2.24 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 102.0 %
      - Above water (accommodation/working, high = better): 98.8 %
   Waterplane Area: 2,377 Square feet or 221 Square metres
   Displacement factor (Displacement / loading): 119 %
   Structure weight / hull surface area: 38 lbs/sq ft or 187 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.90
      - Longitudinal: 2.45
      - Overall: 1.00
   Adequate 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

3t - 1905 FC
10t - SR Wireless
10t - Minesweeping Gear
14t - Electric Drive

Range: 700nm at 10kts

[Kaiser Kirk]

So this is the ship that sparked the Petrol Motor-Electric Drive question, until I realized it was a moot point since you can't increase bunkerage in a refurbishment, so going with an electric drive is the best option.

I've found that simply putting in new Reciprocating engines works pretty well.  I don't necessarily need Turbines + Electric.

[Desertfox]

The main problem is that these ships are quite short-legged, and you can't increase bunkerage with a refurbishment, so the only way to increase range is by using petrol-electric. Oil-fired reciprocating also works as well but without the range boost.

[snip]

Honestly for the price I would just consider building some new hulls and giving these a more basic refit with wireless, etc. The range they have is still good enough to coastal work and they could free up newer, longer ranged hulls for the duties that require them.