Logi's Design Studies

[KWorld]

At that speed, it will be hard to catch, yes.

[Logi]

The machinery space required is too large such that though I can save strength with the switch to 4"/25 I can't shrink the ship.
As a result, I thickened the armor instead.

Kaze, Japan Commerce Raider laid down 1880

Displacement:
   6,000 t light; 6,155 t standard; 7,066 t normal; 7,795 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (454.56 ft / 450.00 ft) x 50.00 ft x (22.00 / 23.70 ft)
   (138.55 m / 137.16 m) x 15.24 m  x (6.71 / 7.22 m)

Armament:
      5 - 4.00" / 102 mm 25.0 cal guns - 25.00lbs / 11.34kg shells, 200 per gun
     Breech loading guns in deck mounts, 1880 Model
     5 x Single mounts on centreline, evenly spread
      Weight of broadside 125 lbs / 57 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   3.00" / 76 mm   450.00 ft / 137.16 m   8.00 ft / 2.44 m
     Main Belt covers 154 % of normal length

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

   - Protected deck - single deck:
   For and Aft decks: 0.50" / 13 mm
   Forecastle: 0.50" / 13 mm  Quarter deck: 0.50" / 13 mm

   - Conning towers: Forward 1.55" / 39 mm, Aft 0.00" / 0 mm

Machinery:
   Coal fired boilers, simple reciprocating steam engines,
   Direct drive, 2 shafts, 16,091 ihp / 12,004 Kw = 21.00 kts
   Range 10,000nm at 7.00 kts
   Bunker at max displacement = 1,639 tons (100% coal)

Complement:
   384 - 500

Cost:
   £0.679 million / $2.716 million

Distribution of weights at normal displacement:
   Armament: 12 tons, 0.2 %
      - Guns: 12 tons, 0.2 %
   Armour: 563 tons, 8.0 %
      - Belts: 400 tons, 5.7 %
      - Armament: 12 tons, 0.2 %
      - Armour Deck: 140 tons, 2.0 %
      - Conning Tower: 12 tons, 0.2 %
   Machinery: 3,325 tons, 47.1 %
   Hull, fittings & equipment: 2,100 tons, 29.7 %
   Fuel, ammunition & stores: 1,066 tons, 15.1 %
   Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     2,819 lbs / 1,279 Kg = 103.6 x 4.0 " / 102 mm shells or 0.6 torpedoes
   Stability (Unstable if below 1.00): 1.60
   Metacentric height 3.9 ft / 1.2 m
   Roll period: 10.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 100 %
         - Recoil effect (Restricted arc if above 1.00): 0.02
   Seaboat quality  (Average = 1.00): 1.56

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.500 / 0.512
   Length to Beam Ratio: 9.00 : 1
   'Natural speed' for length: 21.21 kts
   Power going to wave formation at top speed: 42 %
   Trim (Max stability = 0, Max steadiness = 100): 66
   Bow angle (Positive = bow angles forward): 15.00 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 %,  17.00 ft / 5.18 m,  13.00 ft / 3.96 m
      - Forward deck:   30.00 %,  13.00 ft / 3.96 m,  12.00 ft / 3.66 m
      - Aft deck:   35.00 %,  12.00 ft / 3.66 m,  12.00 ft / 3.66 m
      - Quarter deck:   15.00 %,  12.00 ft / 3.66 m,  12.00 ft / 3.66 m
      - Average freeboard:      12.67 ft / 3.86 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 152.9 %
      - Above water (accommodation/working, high = better): 90.9 %
   Waterplane Area: 14,986 Square feet or 1,392 Square metres
   Displacement factor (Displacement / loading): 98 %
   Structure weight / hull surface area: 87 lbs/sq ft or 423 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.97
      - Longitudinal: 1.20
      - 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

[KWorld]

For sinking freighters, 4" guns are probably smaller than ideal, just as 8" guns are probably larger than ideal.  A gun firing around a 100 pound shell is probably about what you want.

[Logi]

Hm, how is this then? Replaced 4"/25s firing 25lb shells with 6"/25s firing 80lb shells.

Kaze, Japan Commerce Raider laid down 1880

Displacement:
   6,000 t light; 6,177 t standard; 7,097 t normal; 7,833 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (454.29 ft / 450.00 ft) x 48.00 ft x (23.00 / 24.79 ft)
   (138.47 m / 137.16 m) x 14.63 m  x (7.01 / 7.56 m)

Armament:
      4 - 6.00" / 152 mm 25.0 cal guns - 80.00lbs / 36.29kg shells, 200 per gun
     Breech loading guns in deck mounts, 1880 Model
     4 x Single mounts on centreline, evenly spread
      Weight of broadside 320 lbs / 145 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   3.00" / 76 mm   450.00 ft / 137.16 m   8.00 ft / 2.44 m
     Main Belt covers 154 % of normal length

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

   - Protected deck - single deck:
   For and Aft decks: 0.50" / 13 mm
   Forecastle: 0.50" / 13 mm  Quarter deck: 0.50" / 13 mm

   - Conning towers: Forward 1.60" / 41 mm, Aft 0.00" / 0 mm

Machinery:
   Coal fired boilers, simple reciprocating steam engines,
   Direct drive, 2 shafts, 16,127 ihp / 12,031 Kw = 21.00 kts
   Range 10,000nm at 7.00 kts
   Bunker at max displacement = 1,656 tons (100% coal)

Complement:
   386 - 502

Cost:
   £0.686 million / $2.744 million

Distribution of weights at normal displacement:
   Armament: 30 tons, 0.4 %
      - Guns: 30 tons, 0.4 %
   Armour: 558 tons, 7.9 %
      - Belts: 400 tons, 5.6 %
      - Armament: 11 tons, 0.2 %
      - Armour Deck: 134 tons, 1.9 %
      - Conning Tower: 13 tons, 0.2 %
   Machinery: 3,332 tons, 47.0 %
   Hull, fittings & equipment: 2,080 tons, 29.3 %
   Fuel, ammunition & stores: 1,097 tons, 15.5 %
   Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     2,702 lbs / 1,226 Kg = 29.4 x 6.0 " / 152 mm shells or 0.6 torpedoes
   Stability (Unstable if below 1.00): 1.55
   Metacentric height 3.5 ft / 1.1 m
   Roll period: 10.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 100 %
         - Recoil effect (Restricted arc if above 1.00): 0.06
   Seaboat quality  (Average = 1.00): 1.53

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.500 / 0.512
   Length to Beam Ratio: 9.38 : 1
   'Natural speed' for length: 21.21 kts
   Power going to wave formation at top speed: 42 %
   Trim (Max stability = 0, Max steadiness = 100): 66
   Bow angle (Positive = bow angles forward): 15.00 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 %,  16.00 ft / 4.88 m,  13.00 ft / 3.96 m
      - Forward deck:   30.00 %,  13.00 ft / 3.96 m,  12.00 ft / 3.66 m
      - Aft deck:   35.00 %,  12.00 ft / 3.66 m,  12.00 ft / 3.66 m
      - Quarter deck:   15.00 %,  12.00 ft / 3.66 m,  12.00 ft / 3.66 m
      - Average freeboard:      12.59 ft / 3.84 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 153.6 %
      - Above water (accommodation/working, high = better): 86.9 %
   Waterplane Area: 14,391 Square feet or 1,337 Square metres
   Displacement factor (Displacement / loading): 97 %
   Structure weight / hull surface area: 87 lbs/sq ft or 424 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.97
      - Longitudinal: 1.25
      - Overall: 1.00
   Cramped machinery, storage, compartmentation space
   Cramped 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

[KWorld]

That's probably the best balanced of the bunch.  Of course, the danger for any vessel like this is the bad luck of running into an enemy in the darkness or bad weather, where she could find herself in enemy gun range before she can build up steam nad flee.

[Logi]

Yuri, IJN Troopship laid down 1870

Displacement:
   3,500 t light; 3,593 t standard; 4,460 t normal; 5,154 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (254.64 ft / 250.00 ft) x 40.00 ft x (23.00 / 26.12 ft)
   (77.62 m / 76.20 m) x 12.19 m  x (7.01 / 7.96 m)

Armament:
      4 - 3.00" / 76.2 mm 15.0 cal guns - 10.00lbs / 4.54kg shells, 150 per gun
     Muzzle loading guns in deck mounts, 1870 Model
     4 x Single mounts on centreline, evenly spread
      Weight of broadside 40 lbs / 18 kg

Machinery:
   Coal fired boilers, simple reciprocating steam engines,
   Direct drive, 1 shaft, 319 ihp / 238 Kw = 7.00 kts
   Range 10,000nm at 7.00 kts
   Bunker at max displacement = 1,561 tons (100% coal)

Complement:
   272 - 354

Cost:
   £0.134 million / $0.537 million

Distribution of weights at normal displacement:
   Armament: 2 tons, 0.0 %
      - Guns: 2 tons, 0.0 %
   Machinery: 78 tons, 1.8 %
   Hull, fittings & equipment: 1,420 tons, 31.8 %
   Fuel, ammunition & stores: 960 tons, 21.5 %
   Miscellaneous weights: 2,000 tons, 44.8 %
      - Hull below water: 1,000 tons
      - Hull above water: 1,000 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     6,464 lbs / 2,932 Kg = 684.0 x 3.0 " / 76 mm shells or 1.8 torpedoes
   Stability (Unstable if below 1.00): 1.16
   Metacentric height 1.7 ft / 0.5 m
   Roll period: 13.0 seconds
   Steadiness   - As gun platform (Average = 50 %): 80 %
         - Recoil effect (Restricted arc if above 1.00): 0.03
   Seaboat quality  (Average = 1.00): 2.00

Hull form characteristics:
   Hull has low forecastle, low quarterdeck ,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.679 / 0.691
   Length to Beam Ratio: 6.25 : 1
   'Natural speed' for length: 15.81 kts
   Power going to wave formation at top speed: 17 %
   Trim (Max stability = 0, Max steadiness = 100): 40
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 2.00 ft / 0.61 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  15.00 ft / 4.57 m,  15.00 ft / 4.57 m
      - Forward deck:   30.00 %,  23.00 ft / 7.01 m,  23.00 ft / 7.01 m
      - Aft deck:   35.00 %,  23.00 ft / 7.01 m,  23.00 ft / 7.01 m
      - Quarter deck:   15.00 %,  15.00 ft / 4.57 m,  15.00 ft / 4.57 m
      - Average freeboard:      20.20 ft / 6.16 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 55.6 %
      - Above water (accommodation/working, high = better): 125.4 %
   Waterplane Area: 7,787 Square feet or 723 Square metres
   Displacement factor (Displacement / loading): 206 %
   Structure weight / hull surface area: 80 lbs/sq ft or 392 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.78
      - Longitudinal: 8.71
      - Overall: 1.00
   Excellent machinery, storage, compartmentation space
   Excellent 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

2,000 tons for 1,000 troops

[KWorld]

I seems OK by the rules, but why would a Japanese troopship have a) no sails, and b) 10,000 miles of range under steam?  The engine is all but certain to have several failures within that period of use, and the ship has no other means of propulsion.

[Logi]

a) I didn't want to bother adding the misc. weight. It's a hassle to calculate.
b) For range since the ship has no sails.

I'm not sure what system we're using for sail speed anymore.

[Jefgte]

You have 1561 tons of coal for a 3500 tons ship.

Use sails are certainly economical

Jef

[KWorld]

My point on the question about a 10,000 nm range is where is Japan, in 1870, thinking of going that needs 10,000 miles of unrefueled range?  It's only 9294 nm to Valparaiso from Tokyo, after all......

[Logi]

Some ports do not have capacity to support a fleet train.The ship carries enough coal to loiter in the area and to top off other ship's bunkers in foreign ports.

[KWorld]

I'd think the job of refueling the fleet would fall to a collier, unloading from your bunkers isn't going to be an easy task (collecting the coal, bagging it, getting it up to the main deck, then across to the other ship).  On a collier, it wouldn't be unbagged and it would be stored in a hold, so just a matter of swinging the coal across to the other ship.

[Logi]

A tiny, inexpensive commerce raider. The intention is to use sails to navigate in general and use steam only to catch merchants or run away.

The virtue of the ship is the small amount of resources they drain, in materials and fuel, while greatly increasing the risk to enemy shipping. A few operating out of Okinawa, for example, could potentially paralyze the East China Sea trade. The lost of a few by enemy fire or other situations, at the same time, is no great blow to Japan.

H-18 Scheme 2,  Commerce Raider laid down 1870
Corvette (Unarmoured)

Displacement:
   1,000 t light; 1,040 t standard; 1,083 t normal; 1,118 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (200.00 ft / 196.00 ft) x 23.00 ft x (15.00 / 15.39 ft)
   (60.96 m / 59.74 m) x 7.01 m  x (4.57 / 4.69 m)

Armament:
      2 - 6.00" / 152 mm 25.0 cal guns - 80.00lbs / 36.29kg shells, 200 per gun
     Muzzle loading guns in deck mounts, 1870 Model
     2 x Single mounts on centreline, evenly spread
      Weight of broadside 160 lbs / 73 kg

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

Machinery:
   Coal fired boilers, simple reciprocating steam engines,
   Direct drive, 1 shaft, 4,197 ihp / 3,131 Kw = 18.00 kts
   Range 1,000nm at 7.00 kts
   Bunker at max displacement = 78 tons (100% coal)

Complement:
   93 - 122

Cost:
   £0.123 million / $0.493 million

Distribution of weights at normal displacement:
   Armament: 13 tons, 1.2 %
      - Guns: 13 tons, 1.2 %
   Armour: 3 tons, 0.3 %
      - Armament: 3 tons, 0.3 %
   Machinery: 600 tons, 55.4 %
   Hull, fittings & equipment: 330 tons, 30.5 %
   Fuel, ammunition & stores: 83 tons, 7.6 %
   Miscellaneous weights: 54 tons, 5.0 %
      - Above deck: 54 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     198 lbs / 90 Kg = 2.6 x 6.0 " / 152 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.16
   Metacentric height 0.7 ft / 0.2 m
   Roll period: 11.3 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.28
   Seaboat quality  (Average = 1.00): 1.03

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.561 / 0.564
   Length to Beam Ratio: 8.52 : 1
   'Natural speed' for length: 14.00 kts
   Power going to wave formation at top speed: 58 %
   Trim (Max stability = 0, Max steadiness = 100): 48
   Bow angle (Positive = bow angles forward): 20.00 degrees
   Stern overhang: 0.36 ft / 0.11 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  10.00 ft / 3.05 m,  8.00 ft / 2.44 m
      - Forward deck:   30.00 %,  8.00 ft / 2.44 m,  8.00 ft / 2.44 m
      - Aft deck:   30.00 %,  8.00 ft / 2.44 m,  8.00 ft / 2.44 m
      - Quarter deck:   20.00 %,  8.00 ft / 2.44 m,  8.00 ft / 2.44 m
      - Average freeboard:      8.16 ft / 2.49 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 183.9 %
      - Above water (accommodation/working, high = better): 50.6 %
   Waterplane Area: 3,087 Square feet or 287 Square metres
   Displacement factor (Displacement / loading): 50 %
   Structure weight / hull surface area: 54 lbs/sq ft or 264 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.89
      - Longitudinal: 2.71
      - Overall: 1.00
   Cramped machinery, storage, compartmentation space
   Cramped accommodation and workspace room

Sail speed       =        7.0 knots

[KWorld]

How far can it run at full speed?


2 80 pounders might be a bit marginal for armament, for a commerce raider, merchantmen in China Sea area are commonly armed at this period because of the risk of piracy.  They'll be lighter smoothbore weapons, almpst certainly, but  2 guns may not be enough to overawe them into a surrender.

[Logi]

That's simply not true. But your logic, the Chinese merchants would have been armed for over a millennium since the plague of piracy along Chinese coasts has been a long-standing thing. Yet the fact that the pirates continued their business without having as many weapons as you claim to need, means merchant ships, despite the threat were not armed to repel them. (In fact many just paid tribute or gave away part of their cargo to avoid trouble)

Another point is that an armed merchant is far different than a warship in that merchants are not well trained in gunnery and other tactics. When push comes to shove, most of them will panic. The warship has the advantage in both superior construction material, training, and experience. We had this discussion in N3.

Also add that most shipping in the region are still junks, an all black iron-hulled ship will still scare many a merchant.

If we look at the Battle of Tonkin River for the example of the armament of the typical pirates of the period, we see they had 10-6 long 18-lbers guns for each junk. That means a broadside of 5-3 18-lbers, ie 90-54lb broadside weight. The 6" gun fires a 80 lb shell and the centerline mounting means a a broadside weight of 160lb. (Not to mention the 6" gun fires further, is more "awe"-inspiring, and is more accurate at the ranges they duel).