Japan 1870 Start

[Walter]

*looks at freeboard*
Hmmm... perhaps replacing the guns with 2x2 12" guns in the near future during a rebuild to get something like HMS Captain.  ;D

[Logi]

SS was being quite strange, I had it at 12' flush with a bow height of 13'. That was 1.22 seakeeping, then I dropped the bow to 12' and suddenly the seakeeping was 2.00 and the stability 0.20.

In any case, the GM_T in question is 2.1'. The GZ is 0.508 at 14 degrees of heel and the Righting Moment is 1,771 foot-tons. While more than 3 times less than that of the HMS Monarch (6,500 foot-ton, 0.781 GZ), it is more than quadruple that of the HMS Captain (410 foot-ton, 0.053 GZ) which capsized.

Some other examples:
The USS Texas had a GZ of 0.614 and a righting moment of 3,880 foot-tons.
The USS Detroit (CL-10) had a GM_T of 3' 7". The GZ would be 0.866 and a righting moment of 1,815 foot-tons.

The Detroit was considered stable, and in a New York Times article (1891) reporting on the Philadelphia GM issue, it states that 12" is considered safe while 14-16" are fighting qualities for the ship.
Following this, if the Detroit has a GM_T 16", the GZ and righting moment are respectively 0.32256 and 675 foot-ton.

Given the GZ of the H-10 Scheme 5 is 0.508, well above the fighting quality of 0.323 and close to that of Texas's 0.614, this leads me to believe that it should fare decently. However a rebuild along your lines could be well worth it if the GZ remains safely high! :D

[Logi]

A rebuilt H-10, I removed 12 8" guns for 2x2 12" guns centerline. Not much else is changed. The GZ is 0.496 at 14 degrees and the right moment is 1,728 foot-ton. Not big enough change to capsize it ala HMS Captain. However, the recoil got larger than I am typically comfortable with.

A question since it's been a while since I designed a rebuilt ship - when you rebuild the ship, according to the rules does laid down date change? I know engine date doesn't change unless you are replacing the machinery.

H-10 Scheme 5 Rebuilt,  Scout Battleship laid down 1870
Armoured Corvette (Broadside ironclad)

Displacement:
   3,073 t light; 3,284 t standard; 3,485 t normal; 3,647 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (263.28 ft / 260.00 ft) x 42.50 ft x (19.00 / 19.73 ft)
   (80.25 m / 79.25 m) x 12.95 m  x (5.79 / 6.01 m)

Armament:
      14 - 8.00" / 203 mm 14.8 cal guns - 174.76lbs / 79.27kg shells, 85 per gun
     Muzzle loading guns in broadside mounts, 1870 Model
     14 x Single mounts on sides, evenly spread
      4 - 12.00" / 305 mm 15.0 cal guns - 700.00lbs / 317.51kg shells, 16 per gun
     Muzzle loading guns in deck mounts, 1870 Model
     2 x Twin mounts on sides amidships
      Weight of broadside 5,247 lbs / 2,380 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   3.00" / 76 mm   160.00 ft / 48.77 m   9.00 ft / 2.74 m
   Ends:   Unarmoured
     Main Belt covers 95 % of normal length

   - Armoured deck - single deck:
   For and Aft decks: 1.00" / 25 mm
   Forecastle: 1.00" / 25 mm  Quarter deck: 1.00" / 25 mm

Machinery:
   Coal fired boilers, simple reciprocating steam engines, 
   Direct drive, 1 shaft, 2,993 ihp / 2,233 Kw = 14.00 kts
   Range 2,500nm at 7.00 kts
   Bunker at max displacement = 363 tons (100% coal)

Complement:
   226 - 294

Cost:
   £0.291 million / $1.164 million

Distribution of weights at normal displacement:
   Armament: 195 tons, 5.6 %
      - Guns: 195 tons, 5.6 %
   Armour: 336 tons, 9.6 %
      - Belts: 192 tons, 5.5 %
      - Armour Deck: 144 tons, 4.1 %
   Machinery: 734 tons, 21.0 %
   Hull, fittings & equipment: 1,320 tons, 37.9 %
   Fuel, ammunition & stores: 412 tons, 11.8 %
   Miscellaneous weights: 488 tons, 14.0 %
      - Above deck: 488 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     2,114 lbs / 959 Kg = 11.8 x 8.0 " / 203 mm shells or 0.9 torpedoes
   Stability (Unstable if below 1.00): 1.24
   Metacentric height 2.1 ft / 0.6 m
   Roll period: 12.5 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.80
   Seaboat quality  (Average = 1.00): 1.20

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.581 / 0.585
   Length to Beam Ratio: 6.12 : 1
   'Natural speed' for length: 16.12 kts
   Power going to wave formation at top speed: 43 %
   Trim (Max stability = 0, Max steadiness = 100): 42
   Bow angle (Positive = bow angles forward): 20.00 degrees
   Stern overhang: -3.00 ft / -0.91 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  9.00 ft / 2.74 m,  7.00 ft / 2.13 m
      - Forward deck:   30.00 %,  7.00 ft / 2.13 m,  7.00 ft / 2.13 m
      - Aft deck:   30.00 %,  7.00 ft / 2.13 m,  7.00 ft / 2.13 m
      - Quarter deck:   20.00 %,  7.00 ft / 2.13 m,  7.00 ft / 2.13 m
      - Average freeboard:      7.16 ft / 2.18 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 92.4 %
      - Above water (accommodation/working, high = better): 45.7 %
   Waterplane Area: 7,741 Square feet or 719 Square metres
   Displacement factor (Displacement / loading): 114 %
   Structure weight / hull surface area: 121 lbs/sq ft or 591 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.90
      - Longitudinal: 2.45
      - Overall: 1.00
   Adequate machinery, storage, compartmentation space
   Extremely poor accommodation and workspace room

Sail speed          =     16.0 knots

Displacement        =  3,496.0 tons
   7 knots ( 5%)    =    174.8 tons
16 knots (14%)      =    489.4 tons

[Walter]

SS was being quite strange, I had it at 12' flush with a bow height of 13'. That was 1.22 seakeeping, then I dropped the bow to 12' and suddenly the seakeeping was 2.00 and the stability 0.20.

Not sure what is going on there. Perhaps you accidentally entered an additional number in one of the freeboard slots (so it reads for instance 122 feet instead of 12 feet). That is the only thing I can think of.

Throwing the numbers in SS myself, if I raise the ship's freeboard by roughly a deck (7.5 feet in order to keep hull strength at 1.00) and then lower the guns to the upper gundeck, you get "Limited use in all but light seas". Now that makes me wonder (due to lacking knowledge). Would the guns of your sim not have the same problems at that height above the water as the one with the higher freeboard and lowered guns eventhough SS does not say it?

A question since it's been a while since I designed a rebuilt ship - when you rebuild the ship, according to the rules does laid down date change? I know engine date doesn't change unless you are replacing the machinery.

I only change the engine date and only when I replace the machinery with updated engines. I would think that if you put up-to-date guns in there, you'd be changing the gun date as well (just to be safe).

[Logi]

Throwing the numbers in SS myself, if I raise the ship's freeboard by roughly a deck (7.5 feet in order to keep hull strength at 1.00) and then lower the guns to the upper gundeck, you get "Limited use in all but light seas". Now that makes me wonder (due to lacking knowledge). Would the guns of your sim not have the same problems at that height above the water as the one with the higher freeboard and lowered guns eventhough SS does not say it?

That's an interesting question. I don't remember the exact way the SS code handles seakeeping and gun problems and I don't have as much literature on wave propagation and seakeeping as I do on hydrostatics.

According to Hogben and Lumb (1967) + Lee and Bales (1984), the distribution of significant wave heights (crest to trough) in the North Pacific is as follows:

Sea Number	Range (m)	Mean (m)	Probability (%)	Most Probable Wave Period
0-1	0-0.1	0.05	1.30	-
2	0.1-0.5	0.3	6.40	7.5
3	0.5-1.25	0.88	15.50	7.5
4	1.25-2.5	1.88	31.60	8.8
5	2.5-4	3.25	20.94	9.7
6	4-6	5	15.03	12.4
7	6-9	7.5	7.60	15.0
8	9-14	11.5	1.56	16.4
>8	>14	>14	0.07	20.0

If we take the highest tolerated sea state as 6, then 90.77% of all wave heights are tolerated.
It follows that since the values given are <(h_w)_1/3>, <h_w> = 0.625 * <(h_w)_1/3> for sea state 6 according to the Rayleigh density functions.
According to the US Naval Academy (2003), gH/V² = β(F_* - 0.1)²(y/L)^-1/3.
At y/L = 0.01 (bow), L_e = L_forecastle, and d = 4028 m, H = 0.869 m (2.817').
At y/L = 0.2, H = 0.320 m (1.038').
At y/L = 1, H = 0.187 m (0.607').
CCS model says 15.21% deck wetness in sea state 6.


To follow another path of calculations:
According to Tasaki (1963), the bow wave height is 0.99 m.
According to the CCS Model the deck wetness is 19.11% at <(h_w)_1/3>=5m. In sea state 5, the deck wetness is 7.84% at <(h_w)_1/3>=3.25m.



The conclusion is that the design works in general, but ~20% short term wetness is still quite a lot. If I want a deck wetness of 5% in sea state 6, I'll need a minimum bow height of 11'.

I'm not sure but maybe SS sees the problem there as:
In my SS, the guns are deck-level which means the water will wash overboard. In the heightened deck SS, the guns are under the deck and water that floods in will stay in the compartment. This causes the problem SS predicts.

[Logi]

If I raised the deck to 10' with a 11' bow, H-10 looks like this:

H-10 Scheme 5A2,  Scout Battleship laid down 1870
Armoured Corvette (Broadside ironclad)

Displacement:
   3,000 t light; 3,233 t standard; 3,433 t normal; 3,593 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (264.00 ft / 260.00 ft) x 45.00 ft x (19.00 / 19.71 ft)
   (80.47 m / 79.25 m) x 13.72 m  x (5.79 / 6.01 m)

Armament:
      20 - 8.00" / 203 mm 14.8 cal guns - 174.76lbs / 79.27kg shells, 85 per gun
     Muzzle loading guns in broadside mounts, 1870 Model
     20 x Single mounts on sides, evenly spread
      Weight of broadside 3,495 lbs / 1,585 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   3.00" / 76 mm   160.00 ft / 48.77 m   9.00 ft / 2.74 m
   Ends:   Unarmoured
     Main Belt covers 95 % of normal length

   - Armoured deck - single deck:
   For and Aft decks: 1.00" / 25 mm
   Forecastle: 1.00" / 25 mm  Quarter deck: 1.00" / 25 mm

Machinery:
   Coal fired boilers, simple reciprocating steam engines, 
   Direct drive, 1 shaft, 2,947 ihp / 2,199 Kw = 14.00 kts
   Range 2,500nm at 7.00 kts
   Bunker at max displacement = 359 tons (100% coal)

Complement:
   223 - 291

Cost:
   £0.264 million / $1.058 million

Distribution of weights at normal displacement:
   Armament: 157 tons, 4.6 %
      - Guns: 157 tons, 4.6 %
   Armour: 339 tons, 9.9 %
      - Belts: 193 tons, 5.6 %
      - Armour Deck: 146 tons, 4.3 %
   Machinery: 722 tons, 21.0 %
   Hull, fittings & equipment: 1,300 tons, 37.9 %
   Fuel, ammunition & stores: 433 tons, 12.6 %
   Miscellaneous weights: 481 tons, 14.0 %
      - Above deck: 481 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     2,516 lbs / 1,141 Kg = 14.0 x 8.0 " / 203 mm shells or 1.0 torpedoes
   Stability (Unstable if below 1.00): 1.26
   Metacentric height 2.3 ft / 0.7 m
   Roll period: 12.5 seconds
   Steadiness   - As gun platform (Average = 50 %): 72 %
         - Recoil effect (Restricted arc if above 1.00): 0.75
   Seaboat quality  (Average = 1.00): 1.72

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.541 / 0.545
   Length to Beam Ratio: 5.78 : 1
   'Natural speed' for length: 16.12 kts
   Power going to wave formation at top speed: 43 %
   Trim (Max stability = 0, Max steadiness = 100): 42
   Bow angle (Positive = bow angles forward): 20.00 degrees
   Stern overhang: -3.00 ft / -0.91 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  11.00 ft / 3.35 m,  10.00 ft / 3.05 m
      - Forward deck:   30.00 %,  10.00 ft / 3.05 m,  10.00 ft / 3.05 m
      - Aft deck:   30.00 %,  10.00 ft / 3.05 m,  10.00 ft / 3.05 m
      - Quarter deck:   20.00 %,  10.00 ft / 3.05 m,  10.00 ft / 3.05 m
      - Average freeboard:      10.08 ft / 3.07 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 88.2 %
      - Above water (accommodation/working, high = better): 66.9 %
   Waterplane Area: 7,836 Square feet or 728 Square metres
   Displacement factor (Displacement / loading): 122 %
   Structure weight / hull surface area: 112 lbs/sq ft or 546 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.88
      - Longitudinal: 3.01
      - Overall: 1.00
   Adequate 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

Sail speed          =     16.0 knots

Displacement        =  3,433.0 tons
 7 knots ( 5%)      =    171.7 tons
16 knots (14%)      =    480.6 tons

[Logi]

A modification of the H-11 scheme (the workhorse of the fleet).

To standardize the range of the ships (the H-11 is the only <2,500 nm ship), I've warped the hull form a bit and squeezed in a 1,000 nm more range (2,500 nm at 7 knots).

H-11 Scheme 1A2,  Cruiser laid down 1870

Displacement:
   1,500 t light; 1,572 t standard; 1,700 t normal; 1,803 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (213.28 ft / 210.00 ft) x 33.00 ft x (16.00 / 16.78 ft)
   (65.01 m / 64.01 m) x 10.06 m  x (4.88 / 5.11 m)

Armament:
      2 - 8.00" / 203 mm 15.0 cal guns - 120.00lbs / 54.43kg shells, 80 per gun
     Muzzle loading guns in deck mounts, 1870 Model
     2 x Single mounts on sides amidships
      6 - 6.00" / 152 mm 18.0 cal guns - 80.01lbs / 36.29kg shells, 100 per gun
     Muzzle loading guns in deck mounts, 1870 Model
     6 x Single mounts on sides, evenly spread
      Weight of broadside 720 lbs / 327 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.00" / 25 mm         -               -
   2nd:   0.50" / 13 mm         -               -

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

Machinery:
   Coal fired boilers, simple reciprocating steam engines, 
   Direct drive, 1 shaft, 3,418 ihp / 2,549 Kw = 16.00 kts
   Range 2,500nm at 7.00 kts
   Bunker at max displacement = 231 tons (100% coal)

Complement:
   132 - 172

Cost:
   £0.173 million / $0.691 million

Distribution of weights at normal displacement:
   Armament: 45 tons, 2.7 %
      - Guns: 45 tons, 2.7 %
   Armour: 101 tons, 6.0 %
      - Armament: 15 tons, 0.9 %
      - Armour Deck: 86 tons, 5.1 %
   Machinery: 751 tons, 44.2 %
   Hull, fittings & equipment: 518 tons, 30.5 %
   Fuel, ammunition & stores: 200 tons, 11.7 %
   Miscellaneous weights: 85 tons, 5.0 %
      - Above deck: 85 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     428 lbs / 194 Kg = 2.4 x 8.0 " / 203 mm shells or 0.3 torpedoes
   Stability (Unstable if below 1.00): 1.24
   Metacentric height 1.4 ft / 0.4 m
   Roll period: 11.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.33
   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): 0.537 / 0.543
   Length to Beam Ratio: 6.36 : 1
   'Natural speed' for length: 14.49 kts
   Power going to wave formation at top speed: 54 %
   Trim (Max stability = 0, Max steadiness = 100): 69
   Bow angle (Positive = bow angles forward): 20.00 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 %,  9.00 ft / 2.74 m,  7.00 ft / 2.13 m
      - Forward deck:   30.00 %,  7.00 ft / 2.13 m,  6.50 ft / 1.98 m
      - Aft deck:   30.00 %,  6.50 ft / 1.98 m,  6.50 ft / 1.98 m
      - Quarter deck:   20.00 %,  6.50 ft / 1.98 m,  6.50 ft / 1.98 m
      - Average freeboard:      6.84 ft / 2.08 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 152.7 %
      - Above water (accommodation/working, high = better): 44.2 %
   Waterplane Area: 4,621 Square feet or 429 Square metres
   Displacement factor (Displacement / loading): 85 %
   Structure weight / hull surface area: 72 lbs/sq ft or 352 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.91
      - Longitudinal: 2.26
      - Overall: 1.00
   Cramped machinery, storage, compartmentation space
   Extremely poor accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform

Sail speed          =       7.0 knots

Displacement        =   1,700.0 tons
 7 knots ( 5%)      =      85.0 tons