Design Bureau Hong Kong

[Logi]

I desire to know, not to make it pinned on the sim. It is so wrong to want to know?

@Texan: I don't appreciate spam in a thread I created just to avoid clutter. I would like you to delete your non-constructive posts. Seriously.

[Sachmle]

I know the rules, Sam, I was asking from a designer's perspective what negative effects such a L:B ratio generate IRL.

Length/Beam: Number of times the ship is longer than it is wide at it widest in the water. In practice this was virtually always between 5:1 and 10:1. A high ratio will result in a ship that is less stable, has less capacity and is less maneuverable

[Logi]

I know, the thing was: The ship has been adjusted to be stable enough for decent gun-firing. Capacity I know is a problem and so is maneuverability, but I needed the waterline length for the speed of the ship and the increasing the beam threw off the block co-efficent limits and hull strength.

Fixed the hull-strength:

20DD001, RRC Destroyer laid down 1920 (Engine 1916)

Displacement:
   1,000 t light; 1,040 t standard; 1,125 t normal; 1,193 t full load

Dimensions: Length overall / water x beam x draught
   393.00 ft / 377.00 ft x 31.42 ft x 8.75 ft (normal load)
   119.79 m / 114.91 m x 9.58 m  x 2.67 m

Armament:
      4 - 4.72" / 120 mm guns in single mounts, 52.72lbs / 23.91kg shells, 1920 Model
     Breech loading guns in deck mounts
     on centreline ends, evenly spread, 2 raised mounts - superfiring
   Weight of broadside 211 lbs / 96 kg
   Shells per gun, main battery: 150
   12 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   1.00" / 25 mm   0.47" / 12 mm            -

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 29,204 shp / 21,786 Kw = 33.50 kts
   Range 3,000nm at 12.00 kts
   Range    208nm at 33.50 kts
   Bunker at max displacement = 153 tons

   Trial Speed = 34.50 kts

Complement:
   96 - 126

Cost:
   £0.332 million / $1.329 million

Distribution of weights at normal displacement:
   Armament: 26 tons, 2.3 %
   Armour: 9 tons, 0.8 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 9 tons, 0.8 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 596 tons, 53.0 %
   Hull, fittings & equipment: 319 tons, 28.4 %
   Fuel, ammunition & stores: 125 tons, 11.1 %
   Miscellaneous weights: 49 tons, 4.4 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     232 lbs / 105 Kg = 4.4 x 4.7 " / 120 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.09
   Metacentric height 1.0 ft / 0.3 m
   Roll period: 13.0 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.26
   Seaboat quality  (Average = 1.00): 0.78

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.380
   Length to Beam Ratio: 12.00 : 1
   'Natural speed' for length: 19.42 kts
   Power going to wave formation at top speed: 61 %
   Trim (Max stability = 0, Max steadiness = 100): 89
   Bow angle (Positive = bow angles forward): 30.00 degrees
   Stern overhang: 7.34 ft / 2.24 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      15.00 ft / 4.57 m
      - Forecastle (20 %):   12.00 ft / 3.66 m
      - Mid (50 %):      10.50 ft / 3.20 m
      - Quarterdeck (15 %):   9.00 ft / 2.74 m
      - Stern:      9.00 ft / 2.74 m
      - Average freeboard:   10.78 ft / 3.28 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 193.5 %
      - Above water (accommodation/working, high = better): 45.2 %
   Waterplane Area: 7,222 Square feet or 671 Square metres
   Displacement factor (Displacement / loading): 46 %
   Structure weight / hull surface area: 28 lbs/sq ft or 136 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.66
      - Overall: 0.51
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is extremely poor
   Ship has slow, easy roll, a good, steady gun platform
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

Misc Weight:
25t FCS
24t Torpedoes

[Guinness]

IRL: there are issues with both low BCs and high l/b ratios which SS doesn't do a great job of capturing. Long fine hulls tend to be "tender" which means they are liable to hog, twist and sag more than a shorter fuller hull. Of course, the trade off is that a longer finer hull "cuts" through the water better. We have picked standards for both BC and L/B which are in a little bit in excess of what we could find in historical examples based on the idea that OTL naval architects knew what they were doing, etc. etc.

At any rate, I think the issue of L/B specifically can be narrowed down to wanting to maintain adequate initial stability. It is probably not a coincidence that the ships with the highest L/B ratio are often Japanese ships from the 1920s and 1930s. We all remember the Tomozuru incident I'm sure.

I'm reading Friedman's British Destroyers up to WW2 now, and he gets into this subject a little bit, so when I finish that while traveling for the the holidays this year, I hope to have some further insight into British thinking here.

[Logi]

Modifying the gun so the DD becomes a Mini-Cruiser. It hurts.

20DD001, RRC Destroyer laid down 1920 (Engine 1916)

Displacement:
   1,000 t light; 1,083 t standard; 1,170 t normal; 1,239 t full load

Dimensions: Length overall / water x beam x draught
   393.00 ft / 377.00 ft x 31.42 ft x 8.75 ft (normal load)
   119.79 m / 114.91 m x 9.58 m  x 2.67 m

Armament:
      5 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1920 Model
     Breech loading guns in deck mounts
     on centreline ends, majority aft, 2 raised mounts - superfiring
   Weight of broadside 540 lbs / 245 kg
   Shells per gun, main battery: 200
   6 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   2.00" / 51 mm   1.00" / 25 mm            -

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 25,005 shp / 18,654 Kw = 32.00 kts
   Range 3,000nm at 12.00 kts
   Range    238nm at 32.00 kts
   Bunker at max displacement = 156 tons

   Trial Speed = 33 kts

Complement:
   99 - 130

Cost:
   £0.391 million / $1.562 million

Distribution of weights at normal displacement:
   Armament: 68 tons, 5.8 %
   Armour: 33 tons, 2.8 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 33 tons, 2.8 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 525 tons, 44.9 %
   Hull, fittings & equipment: 338 tons, 28.9 %
   Fuel, ammunition & stores: 170 tons, 14.5 %
   Miscellaneous weights: 37 tons, 3.2 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     244 lbs / 111 Kg = 2.3 x 6.0 " / 152 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.25
   Metacentric height 1.3 ft / 0.4 m
   Roll period: 11.5 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.53
   Seaboat quality  (Average = 1.00): 0.80

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.395
   Length to Beam Ratio: 12.00 : 1
   'Natural speed' for length: 19.42 kts
   Power going to wave formation at top speed: 59 %
   Trim (Max stability = 0, Max steadiness = 100): 87
   Bow angle (Positive = bow angles forward): 30.00 degrees
   Stern overhang: 7.34 ft / 2.24 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      15.00 ft / 4.57 m
      - Forecastle (20 %):   12.00 ft / 3.66 m
      - Mid (50 %):      10.00 ft / 3.05 m
      - Quarterdeck (15 %):   8.00 ft / 2.44 m
      - Stern:      9.00 ft / 2.74 m
      - Average freeboard:   10.37 ft / 3.16 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 193.5 %
      - Above water (accommodation/working, high = better): 90.4 %
   Waterplane Area: 7,272 Square feet or 676 Square metres
   Displacement factor (Displacement / loading): 47 %
   Structure weight / hull surface area: 30 lbs/sq ft or 145 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.61
      - Overall: 0.51
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is adequate
   Ship has slow, easy roll, a good, steady gun platform
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

Misc Weight:
25t FCS
12t Torpedoes

[The Rock Doctor]

I think you'd want hoists for those guns.  Manually handling shells of that size will be a hassle.

[Logi]

Put hoists on, reduced the SS speed by 1 kt and reduced the number of shells carried. Seakeeping was, as a result, lowered.

20DD001, RRC Destroyer laid down 1920 (Engine 1916)

Displacement:
   1,000 t light; 1,059 t standard; 1,145 t normal; 1,214 t full load

Dimensions: Length overall / water x beam x draught
   393.00 ft / 377.00 ft x 31.42 ft x 8.75 ft (normal load)
   119.79 m / 114.91 m x 9.58 m  x 2.67 m

Armament:
     5 - 6.00" / 152 mm guns in single mounts, 108.00lbs / 48.99kg shells, 1920 Model
     Breech loading guns in deck mounts with hoists
     on centreline ends, majority aft, 2 raised mounts - superfiring
     Main guns limited to end-on fire
   Weight of broadside 540 lbs / 245 kg
   Shells per gun, main battery: 120
   6 - 21.0" / 533.4 mm above water torpedoes

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

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 21,548 shp / 16,074 Kw = 31.00 kts
   Range 3,000nm at 12.00 kts
  Range    265nm at 31.00 kts
   Bunker at max displacement = 154 tons

  Trial Speed = 33 kts

Complement:
   97 - 127

Cost:
   £0.377 million / $1.510 million

Distribution of weights at normal displacement:
   Armament: 68 tons, 5.9 %
   Armour: 16 tons, 1.4 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 16 tons, 1.4 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 485 tons, 42.4 %
   Hull, fittings & equipment: 394 tons, 34.4 %
   Fuel, ammunition & stores: 145 tons, 12.6 %
   Miscellaneous weights: 37 tons, 3.2 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     245 lbs / 111 Kg = 2.3 x 6.0 " / 152 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.10
   Metacentric height 1.1 ft / 0.3 m
   Roll period: 12.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 53 %
         - Recoil effect (Restricted arc if above 1.00): 1.07
   Seaboat quality  (Average = 1.00): 0.72

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.387
   Length to Beam Ratio: 12.00 : 1
   'Natural speed' for length: 19.42 kts
   Power going to wave formation at top speed: 57 %
   Trim (Max stability = 0, Max steadiness = 100): 73
   Bow angle (Positive = bow angles forward): 30.00 degrees
   Stern overhang: 7.34 ft / 2.24 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      15.00 ft / 4.57 m
      - Forecastle (20 %):   11.50 ft / 3.51 m
      - Mid (50 %):      10.00 ft / 3.05 m
      - Quarterdeck (15 %):   8.00 ft / 2.44 m
      - Stern:      8.00 ft / 2.44 m
      - Average freeboard:   10.16 ft / 3.10 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 184.3 %
      - Above water (accommodation/working, high = better): 90.8 %
   Waterplane Area: 7,242 Square feet or 673 Square metres
   Displacement factor (Displacement / loading): 52 %
   Structure weight / hull surface area: 35 lbs/sq ft or 172 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.55
      - Overall: 0.50
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is adequate
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

Misc Weight:
25t FCS
12t Torpedoes

Seakeeping @ 28 = 0.91
Seakeeping @ 27 = 0.98

[Tanthalas]

6" is to heavy for a DD gun, imagine trying to lug 100 pound weights on a ship that is tossing up and down with every little wave...

[Logi]

That's what the hoists are, right?

[The Rock Doctor]

I understand that they move the shells from storage below decks up to gun deck level, but the shells must be manhandled from there into the gun.

[Logi]

My understanding why the hoists lifted the shell to the gun, the crew loaded the gun and then it was power rammed.

[The Rock Doctor]

We'll need further info, then.

Regardless - setting aside historical hindsight, is the extra punch of the 6" worth the reduced rate of fire?

[Walter]

Looking at AotS: Intrepid, the hoists for the 5" guns don't go further than some sort of storage room just below the turret. From there another set of hoists bring them up into the turret, but it looks like they still needed to be loaded by hand.

[Logi]

@ Rock
Hmm, you're right. The recoil's too high, I just noticed. I switched the guns for 140mms.

@Walter
I was looking the 5"/38. The storage rooms are just below the turret, lifted up by hoist. Then the crew puts on the ram and the power ram rams the shell into the barrel.

20DD001, RRC Destroyer laid down 1920 (Engine 1916)

Displacement:
   1,000 t light; 1,051 t standard; 1,136 t normal; 1,204 t full load

Dimensions: Length overall / water x beam x draught
   393.00 ft / 375.00 ft x 32.60 ft x 8.57 ft (normal load)
   119.79 m / 114.30 m x 9.94 m  x 2.61 m

Armament:
     6 - 5.51" / 140 mm guns in single mounts, 83.72lbs / 37.98kg shells, 1920 Model
     Breech loading guns in deck mounts with hoists
     on centreline ends, evenly spread, 3 raised mounts - superfiring
   Weight of broadside 502 lbs / 228 kg
   Shells per gun, main battery: 100
   6 - 21.0" / 533.4 mm above water torpedoes

Armour:
  - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.75" / 19 mm   0.50" / 13 mm            -

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 21,530 shp / 16,061 Kw = 31.00 kts
   Range 3,000nm at 12.00 kts
  Range    263nm at 31.00 kts
   Bunker at max displacement = 153 tons

  Trial Speed = 32 kts

Complement:
   97 - 127

Cost:
   £0.369 million / $1.476 million

Distribution of weights at normal displacement:
   Armament: 63 tons, 5.5 %
   Armour: 16 tons, 1.4 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 16 tons, 1.4 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 488 tons, 43.0 %
   Hull, fittings & equipment: 396 tons, 34.9 %
   Fuel, ammunition & stores: 136 tons, 12.0 %
   Miscellaneous weights: 37 tons, 3.3 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     258 lbs / 117 Kg = 3.1 x 5.5 " / 140 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.10
   Metacentric height 1.1 ft / 0.3 m
   Roll period: 13.0 seconds
   Steadiness   - As gun platform (Average = 50 %): 54 %
         - Recoil effect (Restricted arc if above 1.00): 0.95
   Seaboat quality  (Average = 1.00): 0.72

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.380
   Length to Beam Ratio: 11.50 : 1
   'Natural speed' for length: 19.36 kts
   Power going to wave formation at top speed: 58 %
   Trim (Max stability = 0, Max steadiness = 100): 75
   Bow angle (Positive = bow angles forward): 35.00 degrees
   Stern overhang: 7.50 ft / 2.29 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      15.00 ft / 4.57 m
      - Forecastle (15 %):   11.50 ft / 3.51 m
      - Mid (50 %):      10.00 ft / 3.05 m
      - Quarterdeck (10 %):   9.00 ft / 2.74 m
      - Stern:      9.00 ft / 2.74 m
      - Average freeboard:   10.40 ft / 3.17 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 183.0 %
      - Above water (accommodation/working, high = better): 97.7 %
   Waterplane Area: 7,452 Square feet or 692 Square metres
   Displacement factor (Displacement / loading): 53 %
   Structure weight / hull surface area: 35 lbs/sq ft or 171 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 0.57
      - Overall: 0.50
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is adequate
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

Misc Weight:
25t FCS
12t Torpedoes

Seakeeping @ 28 = 0.90
Seakeeping @ 27 = 0.98

[Walter]

I was looking the 5"/38. The storage rooms are just below the turret, lifted up by hoist. Then the crew puts on the ram and the power ram rams the shell into the barrel.

Yes, I actually meant the bit to get the shell and powder from the hoists to the ramming position, not the actual loading itself. I would have to look for the photos of HMS Belfast to see how the 6" shells were handled there in the turret.