El Acorazado Concreto

[miketr]

The question is the Concrete Battleship isn't a normal coastal defence battery.  So do the standard rules apply?

Fortaleza el Fraile, Iberia Coastal Defence Battery laid down 1916

Displacement:
   -981 t light; 0 t standard; 0 t normal; 0 t full load

Dimensions: Length overall / water x beam x draught
   0.00 ft / 0.00 ft x 0.00 ft x 0.00 ft (normal load)
   0.00 m / 0.00 m x 0.00 m  x 0.00 m

Armament:
      4 - 13.78" / 350 mm guns (2x2 guns), 1,308.20lbs / 593.39kg shells, 1916 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, evenly spread
      4 - 5.91" / 150 mm guns in single mounts, 102.98lbs / 46.71kg shells, 1916 Model
     Breech loading guns in casemate mounts
     on side, all amidships
      8 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1916 Model
     Quick firing guns in deck mounts
     on side, evenly spread
      2 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1916 Model
     Anti-aircraft guns in deck mounts
     on side, evenly spread
   Weight of broadside 5,773 lbs / 2,619 kg
   Shells per gun, main battery: 300
   4 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   13.0" / 330 mm   9.06" / 230 mm      13.0" / 330 mm
   2nd:   3.94" / 100 mm         -               -
   3rd:   0.98" / 25 mm         -               -
   4th:   0.98" / 25 mm         -               -

   -

Machinery:
   Immobile floating battery

Complement:
   0 - 0

Cost:
   £0.936 million / $3.743 million

Distribution of weights at normal displacement:
   Armament: 722 tons, 0.0 %
   Armour: 544 tons, 0.0 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 544 tons, 0.0 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 0 tons, 0.0 %
   Hull, fittings & equipment: -2,547 tons, 0.0 %
   Fuel, ammunition & stores: 981 tons, 0.0 %
   Miscellaneous weights: 300 tons, 0.0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     NaN lbs / NaN Kg = NaN x 13.8 " / 350 mm shells or NaN torpedoes
   Stability (Unstable if below 1.00): NaN
   Metacentric height NaN ft / NaN m
   Roll period: NaN seconds
   Steadiness   - As gun platform (Average = 50 %): NaN %
         - Recoil effect (Restricted arc if above 1.00): NaN
   Seaboat quality  (Average = 1.00): NaN

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.550
   Length to Beam Ratio: 0.00 : 1
   'Natural speed' for length: 0.00 kts
   Power going to wave formation at top speed: 0 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   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:      0.00 ft / 0.00 m
      - Forecastle (20 %):   0.00 ft / 0.00 m
      - Mid (50 %):      0.00 ft / 0.00 m
      - Quarterdeck (15 %):   0.00 ft / 0.00 m
      - Stern:      0.00 ft / 0.00 m
      - Average freeboard:   0.00 ft / 0.00 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): NaN
      - Above water (accommodation/working, high = better): NaN
   Waterplane Area: 0 Square feet or 0 Square metres
   Displacement factor (Displacement / loading): 0 %
   Structure weight / hull surface area: -Infinity lbs/sq ft or -Infinity Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: NaN
      - Longitudinal: NaN
      - Overall: NaN
   Hull space for machinery, storage, compartmentation is extremely poor
   Room for accommodation and workspaces is extremely poor

This is what looks like the SS of the fort as a ship (freeboard still set to zero)

Fortaleza el Fraile, Iberia Coastal Defence Battery laid down 1916

Displacement:
   36,201 t light; 37,440 t standard; 37,440 t normal; 37,440 t full load

Dimensions: Length overall / water x beam x draught
   350.00 ft / 350.00 ft x 144.00 ft x 40.00 ft (normal load)
   106.68 m / 106.68 m x 43.89 m  x 12.19 m

Armament:
      4 - 13.78" / 350 mm guns (2x2 guns), 1,308.20lbs / 593.39kg shells, 1916 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, evenly spread
      4 - 5.91" / 150 mm guns in single mounts, 102.98lbs / 46.71kg shells, 1916 Model
     Breech loading guns in casemate mounts
     on side, all amidships
      8 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1916 Model
     Quick firing guns in deck mounts
     on side, evenly spread
      2 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1916 Model
     Anti-aircraft guns in deck mounts
     on side, evenly spread
   Weight of broadside 5,773 lbs / 2,619 kg
   Shells per gun, main battery: 150
   4 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   13.0" / 330 mm   9.06" / 230 mm      13.0" / 330 mm
   2nd:   3.94" / 100 mm         -               -
   3rd:   0.98" / 25 mm         -               -
   4th:   0.98" / 25 mm         -               -

   - Conning tower: 12.99" / 330 mm

Machinery:
   Immobile floating battery

Complement:
   1,345 - 1,749

Cost:
   £3.065 million / $12.261 million

Distribution of weights at normal displacement:
   Armament: 722 tons, 1.9 %
   Armour: 857 tons, 2.3 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 544 tons, 1.5 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 313 tons, 0.8 %
   Machinery: 0 tons, 0.0 %
   Hull, fittings & equipment: 34,322 tons, 91.7 %
   Fuel, ammunition & stores: 1,239 tons, 3.3 %
   Miscellaneous weights: 300 tons, 0.8 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     188,523 lbs / 85,512 Kg = 144.1 x 13.8 " / 350 mm shells or 25.7 torpedoes
   Stability (Unstable if below 1.00): 3.11
   Metacentric height 45.0 ft / 13.7 m
   Roll period: 9.0 seconds
   Steadiness   - As gun platform (Average = 50 %): 0 %
         - Recoil effect (Restricted arc if above 1.00): 0.00
   Seaboat quality  (Average = 1.00): 0.00

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.650
   Length to Beam Ratio: 2.43 : 1
   'Natural speed' for length: 18.71 kts
   Power going to wave formation at top speed: 0 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   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:      0.00 ft / 0.00 m
      - Forecastle (20 %):   0.00 ft / 0.00 m
      - Mid (50 %):      0.00 ft / 0.00 m
      - Quarterdeck (15 %):   0.00 ft / 0.00 m
      - Stern:      0.00 ft / 0.00 m
      - Average freeboard:   0.00 ft / 0.00 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 17.5 %
      - Above water (accommodation/working, high = better): 0.0 %
   Waterplane Area: 38,069 Square feet or 3,537 Square metres
   Displacement factor (Displacement / loading): 540 %
   Structure weight / hull surface area: 812 lbs/sq ft or 3,967 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 5.28
      - Longitudinal: 10.07
      - Overall: 5.63
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is extremely poor
   Ship has quick, lively roll, not a steady gun platform
   Caution: Lacks seaworthiness - very limited seakeeping ability

[Guinness]

OTL Fort Drum in Manilla Bay didn't float. So if that's the model here, regardless if yours is surrounded by water or not, it's still a coastal battery and not a ship (at least in my opinion).

If you are just trying to build something that incurs roughly equivalent costs, I think you could sim it with very thick deck armor.

What would be helpful if anyone knows, is a rough ratio of krupp cemented (or similar) armor to reinforced concrete. Ie, so many inches of armor = so many inches of reinforced concrete. By this, I mean comparing their penetration characteristics. I'm still assuming that we sim using armor for BP and cost purposes, but that comes out to however much concrete, etc. If I have time later, I'll try to find something.

[miketr]

My gut feeling is that Fort Drum wasn't a normal Fort.  I have scene batteries like Battery Randolph in Waikiki.  They used up much less material than went into the 25' thick concrete clading that was on Ft. Drum.

Michael

[miketr]

Other Normal Batteries

$2 / 2 BP a pop

Manila - Subic Forts, Iberia Coastal Defence Fort laid down 1916

Displacement:
   -290 t light; 0 t standard; 0 t normal; 0 t full load

Dimensions: Length overall / water x beam x draught
   0.00 ft / 0.00 ft x 0.00 ft x 0.00 ft (normal load)
   0.00 m / 0.00 m x 0.00 m  x 0.00 m

Armament:
      2 - 13.78" / 350 mm guns (1x2 guns), 1,308.20lbs / 593.39kg shells, 1916 Model
     Breech loading guns in a turret (on a barbette)
     on centreline forward
      6 - 5.91" / 150 mm guns in single mounts, 102.98lbs / 46.71kg shells, 1916 Model
     Breech loading guns in deck mounts
     on side, all amidships
      6 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1916 Model
     Quick firing guns in deck mounts
     on side, evenly spread
      2 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1916 Model
     Anti-aircraft guns in deck mounts
     on side, evenly spread
   Weight of broadside 3,337 lbs / 1,514 kg
   Shells per gun, main battery: 150
   4 - 21.0" / 533.4 mm submerged torpedo tubes

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   13.0" / 330 mm   9.06" / 230 mm      13.0" / 330 mm
   2nd:   0.98" / 25 mm         -               -
   3rd:   0.98" / 25 mm         -               -
   4th:   0.98" / 25 mm         -               -

Machinery:
   Immobile floating battery

Complement:
   0 - 0

Cost:
   £0.557 million / $2.227 million

Distribution of weights at normal displacement:
   Armament: 417 tons, 0.0 %
   Armour: 269 tons, 0.0 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 269 tons, 0.0 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 0 tons, 0.0 %
   Hull, fittings & equipment: -1,276 tons, 0.0 %
   Fuel, ammunition & stores: 290 tons, 0.0 %
   Miscellaneous weights: 300 tons, 0.0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     NaN lbs / NaN Kg = NaN x 13.8 " / 350 mm shells or NaN torpedoes
   Stability (Unstable if below 1.00): NaN
   Metacentric height NaN ft / NaN m
   Roll period: NaN seconds
   Steadiness   - As gun platform (Average = 50 %): NaN %
         - Recoil effect (Restricted arc if above 1.00): NaN
   Seaboat quality  (Average = 1.00): NaN

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.550
   Length to Beam Ratio: 0.00 : 1
   'Natural speed' for length: 0.00 kts
   Power going to wave formation at top speed: 0 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   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:      0.00 ft / 0.00 m
      - Forecastle (20 %):   0.00 ft / 0.00 m
      - Mid (50 %):      0.00 ft / 0.00 m
      - Quarterdeck (15 %):   0.00 ft / 0.00 m
      - Stern:      0.00 ft / 0.00 m
      - Average freeboard:   0.00 ft / 0.00 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): NaN
      - Above water (accommodation/working, high = better): NaN
   Waterplane Area: 0 Square feet or 0 Square metres
   Displacement factor (Displacement / loading): 0 %
   Structure weight / hull surface area: -Infinity lbs/sq ft or -Infinity Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: NaN
      - Longitudinal: NaN
      - Overall: NaN
   Hull space for machinery, storage, compartmentation is extremely poor
   Room for accommodation and workspaces is extremely poor

[P3D]

With 0 freeboard the barbette height and weight is zero. FYI.

Looking at the 16"/50 penetration tables at navweaps, 1:10 or 1:12 ratio of reinforced concrete gives the same protection.

[miketr]

Freeboard is PITA...  Suggestions as to how I should do this? 

As to the US 16"L50...

http://www.navweaps.com/Weapons/WNUS_16-50_mk7.htm

So from 20K yards on out its roughly 20" of concrete; down to 27.5" at 10K yards.  So with the weapons we have to work with in this time period the concrete BB itself can't be killed. Direct hits to the turrets are something else of course.  As to the rough comparison of concrete to steel it looks to be as P3D said 12" to 1' roughly.  So 25' thick concrete would be a 25" belt and deck.

Michael   

[Guinness]

Well, with my measly little vote, I say go with that ratio for thickness, give it a hull roughly the shape of the concrete battleship, armor all around, and we'll call it done. Maybe model it with turrets but no barbettes?

[miketr]

Looking at info here

http://www.concretebattleship.org/fort_drum_History.htm

"The island itself had been leveled and a reinforced concrete battleship-shaped structure measuring 350 feet long by 144 feet wide had been built upon it. The top deck of the 'battleship' was 40 feet above the mean low water and 20 feet thick, and housed 4 casemated 6in guns and a 60ft fire control cage mast. Its exterior walls ranged between approximately 25 feet and 36 feet thick, making it virtually impregnable to enemy naval attack."

And here

http://www.concretebattleship.org/Construction_Fort_Drum.htm

Not clear how far below the low tide point the foundation went.  They didn't just put 40' of concrete on top of no foundation...  Perhaps they did... the rocky island "The Friar" that they blasted that level...

OK the question for doing a SS of the thing is what to set the draft to and what to set the freeboard to?  The draft is the key as its what will give the weight.   20' sound ok?

[Guinness]

How about something like this? I set the draft to 20 feet and freeboard to 20 feet, so I could get the 40 foot all around "belt" and used 20" for the "deck" (aka the roof). Turrets are a bit thicker than real life probably though. Also note the block coefficient.

I don't think the displacement matters. Instead we'd want to total up the weights.

CSA Concrete Battleship, CSA Fort laid down 1914
DESIGN FAILURE: Armour weight too much for hull
DESIGN FAILURE: Overall load weight too much for hull

Displacement:
   7,506 t light; 8,800 t standard; 8,800 t normal; 8,800 t full load

Dimensions: Length overall / water x beam x draught
   370.00 ft / 350.00 ft x 44.00 ft x 20.00 ft (normal load)
   112.78 m / 106.68 m x 13.41 m  x 6.10 m

Armament:
      4 - 13.50" / 343 mm guns (2x2 guns), 1,500.00lbs / 680.39kg shells, 1914 Model
     Breech loading guns in Coles/Ericsson turrets
     on centreline ends, evenly spread
     Main guns limited to end-on fire
      8 - 5.50" / 140 mm guns in single mounts, 75.00lbs / 34.02kg shells, 1914 Model
     Breech loading guns in casemate mounts
     on side, all amidships
     8 guns in hull casemates - Limited use in heavy seas
   Weight of broadside 6,600 lbs / 2,994 kg
   Shells per gun, main battery: 300

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   20.0" / 508 mm   350.00 ft / 106.68 m   40.00 ft / 12.19 m
   Ends:   Unarmoured
     Main Belt covers 154 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   20.0" / 508 mm   20.0" / 508 mm            -

   - Armour deck: 20.00" / 508 mm

Machinery:
   Immobile floating battery

Complement:
   453 - 590

Cost:
   £1.081 million / $4.324 million

Distribution of weights at normal displacement:
   Armament: 698 tons, 7.9 %
   Armour: 19,613 tons, 222.9 %
      - Belts: 10,360 tons, 117.7 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 3,272 tons, 37.2 %
      - Armour Deck: 5,981 tons, 68.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 0 tons, 0.0 %
   Hull, fittings & equipment: -12,805 tons, -145.5 %
   Fuel, ammunition & stores: 1,294 tons, 14.7 %
   Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     0 lbs / 0 Kg = 0.0 x 13.5 " / 343 mm shells or 0.3 torpedoes
   Stability (Unstable if below 1.00): 0.88
   Metacentric height 1.1 ft / 0.3 m
   Roll period: 17.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 100 %
         - Recoil effect (Restricted arc if above 1.00): 7.98
   Seaboat quality  (Average = 1.00): 2.00

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 1.000
   Length to Beam Ratio: 7.95 : 1
   'Natural speed' for length: 18.71 kts
   Power going to wave formation at top speed: 0 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 0.00 degrees
   Stern overhang: 20.00 ft / 6.10 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      20.00 ft / 6.10 m
      - Forecastle (20 %):   20.00 ft / 6.10 m
      - Mid (50 %):      20.00 ft / 6.10 m
      - Quarterdeck (15 %):   20.00 ft / 6.10 m
      - Stern:      20.00 ft / 6.10 m
      - Average freeboard:   20.00 ft / 6.10 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 69.7 %
      - Above water (accommodation/working, high = better): 135.9 %
   Waterplane Area: 16,165 Square feet or 1,502 Square metres
   Displacement factor (Displacement / loading): 35 %
   Structure weight / hull surface area: -459 lbs/sq ft or -2,239 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: -2.76
      - Longitudinal: -14.00
      - Overall: -9.33
   Caution: Poor stability - excessive risk of capsizing
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is excellent
   Ship has slow, easy roll, a good, steady gun platform
   Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Design Failure: Reduce armour or increase Displacement

[miketr]

My own attempt.

722+2646+12950+1414+14085+197+300=32314... Not sure its worth it at $32 / 32 BP or worse $64 / 64 BP.

Michael

Distribution of weights at normal displacement:
   Armament: 722 tons, 3.9 %
   Armour: 28,646 tons, 153.0 %
      - Belts: 12,950 tons, 69.2 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 1,414 tons, 7.6 %
      - Armour Deck: 14,085 tons, 75.2 %
      - Conning Tower: 197 tons, 1.1 %
   Machinery: 0 tons, 0.0 %
   Hull, fittings & equipment: -12,304 tons, -65.7 %
   Fuel, ammunition & stores: 1,356 tons, 7.2 %
   Miscellaneous weights: 300 tons, 1.6 %

Fortaleza el Fraile, Iberia Coastal Defence Battery laid down 1916
DESIGN FAILURE: Armour weight too much for hull
DESIGN FAILURE: Overall load weight too much for hull

Displacement:
   17,364 t light; 18,720 t standard; 18,720 t normal; 18,720 t full load

Dimensions: Length overall / water x beam x draught
   350.00 ft / 350.00 ft x 144.00 ft x 20.00 ft (normal load)
   106.68 m / 106.68 m x 43.89 m  x 6.10 m

Armament:
      4 - 13.78" / 350 mm guns (2x2 guns), 1,308.20lbs / 593.39kg shells, 1916 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, evenly spread, 1 raised mount
      4 - 5.91" / 150 mm guns in single mounts, 102.98lbs / 46.71kg shells, 1916 Model
     Breech loading guns in casemate mounts
     on side, all amidships
      8 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1916 Model
     Quick firing guns in deck mounts
     on side, evenly spread
      2 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1916 Model
     Anti-aircraft guns in deck mounts
     on side, evenly spread
   Weight of broadside 5,773 lbs / 2,619 kg
   Shells per gun, main battery: 300
   4 - 21.0" / 533.4 mm above water torpedoes

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   25.0" / 635 mm   350.00 ft / 106.68 m   40.00 ft / 12.19 m
   Ends:   Unarmoured
     Main Belt covers 154 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   13.0" / 330 mm   9.06" / 230 mm      13.0" / 330 mm
   2nd:   3.94" / 100 mm         -               -
   3rd:   0.98" / 25 mm         -               -
   4th:   0.98" / 25 mm         -               -

   - Armour deck: 20.00" / 508 mm, Conning tower: 12.99" / 330 mm

Machinery:
   Immobile floating battery

Complement:
   799 - 1,040

Cost:
   £1.986 million / $7.946 million

Distribution of weights at normal displacement:
   Armament: 722 tons, 3.9 %
   Armour: 28,646 tons, 153.0 %
      - Belts: 12,950 tons, 69.2 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 1,414 tons, 7.6 %
      - Armour Deck: 14,085 tons, 75.2 %
      - Conning Tower: 197 tons, 1.1 %
   Machinery: 0 tons, 0.0 %
   Hull, fittings & equipment: -12,304 tons, -65.7 %
   Fuel, ammunition & stores: 1,356 tons, 7.2 %
   Miscellaneous weights: 300 tons, 1.6 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     0 lbs / 0 Kg = 0.0 x 13.8 " / 350 mm shells or 7.3 torpedoes
   Stability (Unstable if below 1.00): 1.80
   Metacentric height 22.4 ft / 6.8 m
   Roll period: 12.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 100 %
         - Recoil effect (Restricted arc if above 1.00): 0.08
   Seaboat quality  (Average = 1.00): 2.00

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0.650
   Length to Beam Ratio: 2.43 : 1
   'Natural speed' for length: 18.71 kts
   Power going to wave formation at top speed: 0 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   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:      20.00 ft / 6.10 m
      - Forecastle (20 %):   20.00 ft / 6.10 m
      - Mid (50 %):      20.00 ft / 6.10 m
      - Quarterdeck (15 %):   20.00 ft / 6.10 m
      - Stern:      20.00 ft / 6.10 m
      - Average freeboard:   20.00 ft / 6.10 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 35.7 %
      - Above water (accommodation/working, high = better): 171.6 %
   Waterplane Area: 38,069 Square feet or 3,537 Square metres
   Displacement factor (Displacement / loading): 54 %
   Structure weight / hull surface area: -285 lbs/sq ft or -1,391 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: -1.45
      - Longitudinal: -6.64
      - Overall: -4.54
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is excellent
   Ship has slow, easy roll, a good, steady gun platform
   Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Design Failure: Reduce armour or increase Displacement

[Guinness]

My own attempt.

722+2646+12950+1414+14085+197+300=32314... Not sure its worth it at $32 / 32 BP or worse $64 / 64 BP.

Michael

Distribution of weights at normal displacement:
   Armament: 722 tons, 3.9 %
   Armour: 28,646 tons, 153.0 %
      - Belts: 12,950 tons, 69.2 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 1,414 tons, 7.6 %
      - Armour Deck: 14,085 tons, 75.2 %
      - Conning Tower: 197 tons, 1.1 %
   Machinery: 0 tons, 0.0 %
   Hull, fittings & equipment: -12,304 tons, -65.7 %
   Fuel, ammunition & stores: 1,356 tons, 7.2 %
   Miscellaneous weights: 300 tons, 1.6 %

Yeah, that's kind of the issue with costing it this way. I don't think concrete should cost nearly as much in BP and $ as the equivalently tough thickness of armor plate. I think more like maybe 1/4 ought to be right, so yours would cost roughly $8/8BP. At least to me, that seems a lot closer to what I'd expect the reality was.

[P3D]

Reinforced concrete costs no BP. The cost of naval fortification is the BP cost of the installed artillery in $. Gun mounts, perhaps FC positions has steel armor, rest is cement.

[maddox]

When this problem came up in Nverse II, the solution was as following.

Forts have a generic pricetag.  The artillery for a fort is the same as used in the artillery of a corps. Because, in the end, you have a small fort that is manned with a corps (or 2, or 3, depending on size of fort) and that gives an defensive bonus.

When the coastal defences were questioned, the solution was simple.
Pricetag of a Fort (whatever size) and then the BP and $ cost of the Springsharp simmed weapons if larger guns for anti shipping work were wished for.

So, rip out a turret and barbette -or something like that- from a ship and use that to determinate the pricetag of the whole setup.

But to make it simple, it's already in the current rules.

http://www.navalism.org/index.php?topic=135.0

So a Fort Drum alike setup.  
Pricetag of a small fort + pricetag of  BB barbettes and Turret setups + pricetag of any gun over normal corps level artillery.

Of course, we understand that you can't lodge a corps (or more) in such a small coastal fortification, and that the defensive land war modifier wouldn't apply for this.

But in effect, a Fort Drum unsinkable BB isn't more than a BIG chunk of reinforced concrete on an island.
It can be destroyed, but that takes a shitload of time and not readely used weapons.

[miketr]

OK stupid question then...  If the official solution is that you take a land fort and plant the naval guns on it then what type of fortress is it? Dated, basic, advanced, etc?

The only reason I am doing this is that I always thought the Concrete BB was cool and since I own the Philippines I should build it sooner or later damn it.  Odds are for the cost standard baterries would be better but it still just a cool idea. 

[maddox]

Directly from the rules.

The fortress have the Artillery rating of three times the corresponding level Infantry corps.

I would say, depending on guns installed - brandnew 1913 guns or  Vanguarded 1895 guns- the firepower of the fortress against naval targets is rated.
If those guns are put against infantry/cavalery/special forces with HE or even shrapnell the only thing that counts is range.
A 1895 gun/shell combo with 200 kg of Shrapnell of a 1913 gun/shell with 220 kg of shrapnell....