Japanese Ship Designs 1915+

[Desertfox]

Cheap colonial/littoral destroyer. Designed to fight in shallow and enclosed waters. Electric drive for maneuverability and a heavy torpedo armament.

Kawakaze class, Japan Littoral Destroyer laid down 1917

Displacement:
   500 t light; 527 t standard; 578 t normal; 619 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (302.12 ft / 300.00 ft) x 25.00 ft x (7.10 / 7.41 ft)
   (92.08 m / 91.44 m) x 7.62 m  x (2.16 / 2.26 m)

Armament:
      3 - 5.00" / 127 mm 45.0 cal guns - 63.03lbs / 28.59kg shells, 130 per gun
     Quick firing guns in deck mounts, 1917 Model
     2 x Single mounts on centreline ends, evenly spread
     1 x Single mount on centreline, aft deck centre
      6 - 2.00" / 50.8 mm 45.0 cal guns - 4.03lbs / 1.83kg shells, 150 per gun
     Quick firing guns in deck mounts, 1917 Model
     2 x Triple mounts on sides amidships
      Weight of broadside 213 lbs / 97 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.50" / 13 mm         -               -

   - Conning towers: Forward 0.50" / 13 mm, Aft 0.00" / 0 mm

Machinery:
   Oil fired boilers, steam turbines,
   Electric motors, 2 shafts, 8,841 shp / 6,595 Kw = 27.00 kts
   Range 2,000nm at 14.00 kts
   Bunker at max displacement = 91 tons

Complement:
   58 - 76

Cost:
   £0.110 million / $0.440 million

Distribution of weights at normal displacement:
   Armament: 37 tons, 6.4 %
      - Guns: 37 tons, 6.4 %
   Armour: 5 tons, 0.8 %
      - Armament: 4 tons, 0.7 %
      - Conning Tower: 1 tons, 0.1 %
   Machinery: 233 tons, 40.3 %
   Hull, fittings & equipment: 136 tons, 23.5 %
   Fuel, ammunition & stores: 78 tons, 13.5 %
   Miscellaneous weights: 89 tons, 15.4 %
      - Hull below water: 58 tons
      - On freeboard deck: 27 tons
      - Above deck: 4 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     196 lbs / 89 Kg = 3.1 x 5.0 " / 127 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.23
   Metacentric height 0.9 ft / 0.3 m
   Roll period: 11.0 seconds
   Steadiness   - As gun platform (Average = 50 %): 69 %
         - Recoil effect (Restricted arc if above 1.00): 0.43
   Seaboat quality  (Average = 1.00): 1.00

Hull form characteristics:
   Hull has low quarterdeck ,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.380 / 0.390
   Length to Beam Ratio: 12.00 : 1
   'Natural speed' for length: 17.32 kts
   Power going to wave formation at top speed: 55 %
   Trim (Max stability = 0, Max steadiness = 100): 69
   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 %,  12.00 ft / 3.66 m,  9.00 ft / 2.74 m
      - Forward deck:   30.00 %,  9.00 ft / 2.74 m,  9.00 ft / 2.74 m
      - Aft deck:   17.00 %,  9.00 ft / 2.74 m,  9.00 ft / 2.74 m
      - Quarter deck:   33.00 %,  7.00 ft / 2.13 m,  7.00 ft / 2.13 m
      - Average freeboard:      8.58 ft / 2.62 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 158.9 %
      - Above water (accommodation/working, high = better): 134.3 %
   Waterplane Area: 4,556 Square feet or 423 Square metres
   Displacement factor (Displacement / loading): 69 %
   Structure weight / hull surface area: 22 lbs/sq ft or 108 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.67
      - Overall: 0.51
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room

4t - 1908 FC
9t - Spare (for now)
18t - 6 x 21" Torpedoes
58t - Electric Drive

[Jefgte]

Machinery: 233 tons, 40.3 %

"Architecture

The Capital Ship Architecture tech applies to any ship carrying guns with a bore diameter of 210mm or more carrying its armament in turrets. If the weapons are less than 210mm or not turreted, the Cruiser Architecture tech applies.

Ships built to Destroyer Architecture must have at least 50% of the Distribution of weights at normal displacement section of their Springsharp allocated to Machinery...

For Destroyer, you need 50% for machinery.
=> Speed update to around 29.5kts.

[TacCovert4]

I think there's a bit of a question about electric drive as its misc weight but also machinery weight.   With the 58t of extra weight for the electric drives its well over the 50% threshold. 

[Desertfox]

Yes the ship has over 50% allocation to machinery, once you add the approximately 10% of misc weight that is part of the electric drive. Electric drive has to be 25% of machinery weight, so if the machinery weight is above 40% then the electric drive will be at least 10% and together they will add up to over 50%.

[snip]

If I recall this discussion the last time it came up: The additional weight added to accommodate Electric Drives or other engine modification does not count towards the 50% minimum. The Machinery weight must on its own be 50% or more.

[Kaiser Kirk]

If I recall this discussion the last time it came up: The additional weight added to accommodate Electric Drives or other engine modification does not count towards the 50% minimum. The Machinery weight must on its own be 50% or more.

If there's been a previous ruling, we'll stick with that.

[Desertfox]

There was a discussion but I don't see a ruling there. 50% machinery should be 50% machinery whether that is steam turbines or electric drives it's all the same.

[snip]

There was a discussion but I don't see a ruling there. 50% machinery should be 50% machinery whether that is steam turbines or electric drives it's all the same.

The important part is "Machinery: xyz tons, xy.z % needs the % to be at least 50.0000000000000000000001 %

Seems definitive to me.

[Desertfox]

But that doesn't say if the electric drive % is included in that or not, which is the question.

[snip]

Its clear to me that whatever the % value listed in the output of the report is the value that needs to be met to be in compliance with the rule. The posted design only has 40.3% and is therefor invalid.

[Desertfox]

The electric drive additional misc weight is mandatory and is absolutely part of the machinery. I don't see any good argument for why we shouldn't be counting it. Note this also applies to hydraulic and diesel engines. Are you saying that destroyers with turbo-electric drives need to have 62.5% of their weight dedicated to machinery alone?

[Kaiser Kirk]

You do not need to use the destroyer architecture, that is a choice you are making.
You are perfectly free to make the choice to use the cruiser rules to make your ship.

If you wish to make the choice to use the Destroyer Architecture standard you are choosing to meet is :
"Ships built to Destroyer Architecture must have at least 50% of the Distribution of weights at normal displacement section of their Springsharp allocated to Machinery."

It's a simple, consistent metric, and compliance can easily be determined and replicated in the springsharp.

Since your choice to use turbo-electric gear is something that we add under miscellaneous weight, it will not be reflected under the Machinery section.

[Desertfox]

Add some inefficiency and coal and it works

Kawakaze class, Japan Littoral Destroyer laid down 1917

Displacement:
   504 t light; 531 t standard; 606 t normal; 666 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (292.29 ft / 290.00 ft) x 25.00 ft x (7.70 / 8.17 ft)
   (89.09 m / 88.39 m) x 7.62 m  x (2.35 / 2.49 m)

Armament:
      3 - 5.00" / 127 mm 45.0 cal guns - 63.03lbs / 28.59kg shells, 130 per gun
     Quick firing guns in deck mounts, 1917 Model
     2 x Single mounts on centreline ends, evenly spread
     1 x Single mount on centreline, aft deck centre
      6 - 2.00" / 50.8 mm 45.0 cal guns - 4.03lbs / 1.83kg shells, 150 per gun
     Quick firing guns in deck mounts, 1917 Model
     2 x Triple mounts on sides amidships
      Weight of broadside 213 lbs / 97 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.10" / 3 mm         -               -

Machinery:
   Coal and oil fired boilers, complex reciprocating steam engines,
   Direct drive, 2 shafts, 9,853 ihp / 7,350 Kw = 27.40 kts
   Range 2,100nm at 14.00 kts
   Bunker at max displacement = 134 tons (40% coal)

Complement:
   60 - 79

Cost:
   £0.128 million / $0.512 million

Distribution of weights at normal displacement:
   Armament: 37 tons, 6.1 %
      - Guns: 37 tons, 6.1 %
   Armour: 1 tons, 0.1 %
      - Armament: 1 tons, 0.1 %
   Machinery: 303 tons, 50.0 %
   Hull, fittings & equipment: 140 tons, 23.1 %
   Fuel, ammunition & stores: 102 tons, 16.9 %
   Miscellaneous weights: 23 tons, 3.8 %
      - On freeboard deck: 18 tons
      - Above deck: 5 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     161 lbs / 73 Kg = 2.6 x 5.0 " / 127 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.27
   Metacentric height 1.0 ft / 0.3 m
   Roll period: 10.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.42
   Seaboat quality  (Average = 1.00): 1.00

Hull form characteristics:
   Hull has low quarterdeck ,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.380 / 0.393
   Length to Beam Ratio: 11.60 : 1
   'Natural speed' for length: 17.03 kts
   Power going to wave formation at top speed: 58 %
   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:   20.00 %,  13.00 ft / 3.96 m,  9.00 ft / 2.74 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:   25.00 %,  7.00 ft / 2.13 m,  7.00 ft / 2.13 m
      - Average freeboard:      8.82 ft / 2.69 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 178.2 %
      - Above water (accommodation/working, high = better): 125.5 %
   Waterplane Area: 4,404 Square feet or 409 Square metres
   Displacement factor (Displacement / loading): 45 %
   Structure weight / hull surface area: 23 lbs/sq ft or 110 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.80
      - Overall: 0.52
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform

5t - 1908 FC
18t - 6 x 21" Torpedoes

[Jefgte]

Well done, VTE are the solution.
Coal is a good option because it allows boilers to run with wood, which is available almost everywhere on the coasts.

[Kaiser Kirk]

I've been toying with similar designs.
I go back and forth on coal.
While Parthia has lot of oil, one of her operating presumptions is that in a war, distant colonies may have to fend for themselves for a while,
so being able to use local coal/wood , or purchase/capture mecantile coal would be advantageous.

Here, you've discovered what I have, that allocating enough machinery to meet the 50% threshold drives the speed too high for seakeeping,
and that machinery seems to have more of an effect on comp hull than simple misc weight.
While since coal has lower thermal efficiency, you need more boilers - hence machinery weight - per shp.
The VTE aspect is a cute workaround to the problems of "too much speed". Technically it's sidestepping the intent of the rules, but it does follow the letter.