Design Bureau Guangzhou

[Carthaginian]

The SMS Bayern, which Samchle linked, has a 0.90 speed/length and causes the wave to expose part of the hull.

But of course, if the main belt could be made taller, it would be better. As the 0.94 number applies only to still waters and moving through them.

Link something explaining this... I can't seem to find anything that covers what your saying in wiki.

[Guinness]

http://en.wikipedia.org/wiki/Wave_making_resistance

My google fu is strong tonight.

[Logi]

I am not that sure on the 0.94 magic number, as I don't have any solid evidence linking to it's supposed effects on bow wave trough. A ship going 0.94 or above matches the bow waves so it settles slightly in the waters instead of rising or being exposed.


I prefer a more detailed calculation.

The Bow Wave height at the forward perpendicular is caluclated by:

h_s = 0.75 x b x ( l / l_e ) x Fr^2

The Froude Number (squared) for the ship in question is 0.0768.... etc.
The ( l / l_e) is irrelevant due to the waterline being the longest length between perpendiculars by the ship.

Thus the h_s as calculated is 1.55 meters or  roughly 5.08 feet.

That means the trough of the wave generated by speed is 5 ft at most. Which means 1' of armored belt remains underwater. Not a lot, but still not exposed.

-----

Calculations for the SMS Bayern.

The Froude Number (squared)  for the Bayern is 0.07254..... etc.

The SMS Bayern also has an inverted bow and a stern hang, so l / l_e must be calculated now. Damnit!

Supposedly the waterline length is 179.4m and the overall length is 180m.

That makes h_s = 1.6376.... meters. Or roughly 5.37 feet.

So 5.37 feet of the underwater hull is exposed. I don't know if the Bayern's armored belt covered that length.

But you are correct, moving through a sea wave (not bow wave alone) would expose the unarmored hull for my ship.

[Logi]

Redesigned. Main belt is sloped 20 degrees giving it a vertical height of 14'. Of this, 6' is above water, 8' is underwater.

Light Ship, RRC Light Battleship laid down 1920 (Engine 1916)

Displacement:
   18,000 t light; 19,171 t standard; 20,418 t normal; 21,415 t full load

Dimensions: Length overall / water x beam x draught
   557.74 ft / 557.74 ft x 88.60 ft x 26.30 ft (normal load)
   170.00 m / 170.00 m x 27.01 m  x 8.02 m

Armament:
     8 - 14.00" / 356 mm guns (2x4 guns), 1,650.00lbs / 748.43kg shells, 1920 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, evenly spread
     12 - 4.13" / 105 mm guns (6x2 guns), 35.32lbs / 16.02kg shells, 1920 Model
     Breech loading guns in deck mounts with hoists
     on side, all amidships
   Weight of broadside 13,624 lbs / 6,180 kg
   Shells per gun, main battery: 100

Armour:
  - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   13.5" / 343 mm   361.00 ft / 110.03 m   15.33 ft / 4.67 m
   Ends:   Unarmoured
     Main Belt covers 100 % of normal length

  - Torpedo Bulkhead:
      2.50" / 64 mm   361.00 ft / 110.03 m   18.30 ft / 5.58 m

  - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   17.0" / 432 mm   3.00" / 76 mm      12.0" / 305 mm
   2nd:   1.00" / 25 mm   1.00" / 25 mm      1.00" / 25 mm

  - Armour deck: 3.00" / 76 mm, Conning tower: 2.00" / 51 mm

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 4 shafts, 32,986 shp / 24,608 Kw = 22.00 kts
   Range 8,000nm at 12.00 kts
   Bunker at max displacement = 2,244 tons

Complement:
   853 - 1,110

Cost:
   £4.725 million / $18.900 million

Distribution of weights at normal displacement:
   Armament: 1,425 tons, 7.0 %
   Armour: 6,883 tons, 33.7 %
      - Belts: 3,266 tons, 16.0 %
      - Torpedo bulkhead: 611 tons, 3.0 %
      - Armament: 1,059 tons, 5.2 %
      - Armour Deck: 1,914 tons, 9.4 %
      - Conning Tower: 32 tons, 0.2 %
   Machinery: 1,229 tons, 6.0 %
   Hull, fittings & equipment: 8,163 tons, 40.0 %
   Fuel, ammunition & stores: 2,418 tons, 11.8 %
   Miscellaneous weights: 301 tons, 1.5 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     22,578 lbs / 10,241 Kg = 16.5 x 14.0 " / 356 mm shells or 4.4 torpedoes
   Stability (Unstable if below 1.00): 1.10
   Metacentric height 5.0 ft / 1.5 m
   Roll period: 16.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.57
   Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.550
   Length to Beam Ratio: 6.30 : 1
   'Natural speed' for length: 23.62 kts
   Power going to wave formation at top speed: 46 %
   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 (% = measuring location as a percentage of overall length):
      - Stem:      13.00 ft / 3.96 m
      - Forecastle (20 %):   12.00 ft / 3.66 m
      - Mid (50 %):      12.00 ft / 3.66 m
      - Quarterdeck (15 %):   12.00 ft / 3.66 m
      - Stern:      12.00 ft / 3.66 m
      - Average freeboard:   12.08 ft / 3.68 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 96.1 %
      - Above water (accommodation/working, high = better): 92.4 %
   Waterplane Area: 34,483 Square feet or 3,204 Square metres
   Displacement factor (Displacement / loading): 97 %
   Structure weight / hull surface area: 183 lbs/sq ft or 892 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.97
      - Longitudinal: 1.30
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is adequate
   Ship has slow, easy roll, a good, steady gun platform

[Carthaginian]

NOW I like.
A great little light BB.

[Logi]

Lengthened the TDS so it overlaps with the Main Belt.

Light Ship, RRC Light Battleship laid down 1920 (Engine 1916)

Displacement:
   18,005 t light; 19,176 t standard; 20,423 t normal; 21,420 t full load

Dimensions: Length overall / water x beam x draught
   557.74 ft / 557.74 ft x 88.60 ft x 26.30 ft (normal load)
   170.00 m / 170.00 m x 27.01 m  x 8.02 m

Armament:
      8 - 14.00" / 356 mm guns (2x4 guns), 1,650.00lbs / 748.43kg shells, 1920 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, evenly spread
      12 - 4.13" / 105 mm guns (6x2 guns), 35.32lbs / 16.02kg shells, 1920 Model
     Breech loading guns in deck mounts with hoists
     on side, all amidships
   Weight of broadside 13,624 lbs / 6,180 kg
   Shells per gun, main battery: 100

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   13.5" / 343 mm   361.00 ft / 110.03 m   15.33 ft / 4.67 m
   Ends:   Unarmoured
     Main Belt covers 100 % of normal length

   - Torpedo Bulkhead:
      2.50" / 64 mm   361.00 ft / 110.03 m   21.60 ft / 6.58 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   16.0" / 406 mm   3.00" / 76 mm      11.0" / 279 mm
   2nd:   0.64" / 16 mm   0.50" / 13 mm      0.50" / 13 mm

   - Armour deck: 3.00" / 76 mm, Conning tower: 2.00" / 51 mm

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 4 shafts, 32,992 shp / 24,612 Kw = 22.00 kts
   Range 8,000nm at 12.00 kts
   Bunker at max displacement = 2,244 tons

Complement:
   853 - 1,110

Cost:
   £4.725 million / $18.902 million

Distribution of weights at normal displacement:
   Armament: 1,425 tons, 7.0 %
   Armour: 6,911 tons, 33.8 %
      - Belts: 3,266 tons, 16.0 %
      - Torpedo bulkhead: 721 tons, 3.5 %
      - Armament: 977 tons, 4.8 %
      - Armour Deck: 1,914 tons, 9.4 %
      - Conning Tower: 32 tons, 0.2 %
   Machinery: 1,229 tons, 6.0 %
   Hull, fittings & equipment: 8,140 tons, 39.9 %
   Fuel, ammunition & stores: 2,418 tons, 11.8 %
   Miscellaneous weights: 300 tons, 1.5 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     22,680 lbs / 10,287 Kg = 16.5 x 14.0 " / 356 mm shells or 4.5 torpedoes
   Stability (Unstable if below 1.00): 1.11
   Metacentric height 5.1 ft / 1.5 m
   Roll period: 16.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.57
   Seaboat quality  (Average = 1.00): 1.02

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.550
   Length to Beam Ratio: 6.30 : 1
   'Natural speed' for length: 23.62 kts
   Power going to wave formation at top speed: 46 %
   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 (% = measuring location as a percentage of overall length):
      - Stem:      13.00 ft / 3.96 m
      - Forecastle (20 %):   12.00 ft / 3.66 m
      - Mid (50 %):      12.00 ft / 3.66 m
      - Quarterdeck (15 %):   12.00 ft / 3.66 m
      - Stern:      12.00 ft / 3.66 m
      - Average freeboard:   12.08 ft / 3.68 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 96.1 %
      - Above water (accommodation/working, high = better): 92.4 %
   Waterplane Area: 34,487 Square feet or 3,204 Square metres
   Displacement factor (Displacement / loading): 97 %
   Structure weight / hull surface area: 182 lbs/sq ft or 890 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.97
      - Longitudinal: 1.31
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is adequate
   Ship has slow, easy roll, a good, steady gun platform