Imperial Roman Navy: 1926-1930 Designs

[TacCovert4]

I tend to go shallow on draft as well, because I work a shallow sea with a lot of shoals.  It increases tactical flexibility.

[Kaiser Kirk]

I was going to opine that I thought the deck armor on the fast battleship too light,
but I may have been too hasty.

I was basing the initial reaction off the numbers for the USN 14"/45 in Navweaps, which are
apparently for the shells in use in 1942. 

The numbers in Navweaps for the RN 15/42 with the 1,938lb are apparently from pre1935 calc
-presumably when upgrading to these were planned- and if scaled for the Roman 16",
I'm thinking the 115mm probably checks out up to the 24km max range.

[snip]

Looking ahead to some refit options, the plan is for the Emperor Trajan VIII class battleships to be retained and form the Mediterranean Fleet's battle squadron with the pending retirement of the older pre-dreads from service. Given their age, some work is needed. The minimum option is presented below. It replaces the old mixed propulsion plan with a diesel electric drive (for an impressive 8578nm range at 14 knts given her limited bunker), refreshes the secondaries and AA to current standards, refreshes the main battery with guns which can fire an impressive 625kg shell, adds new deck armor, and improves MISC weight for fun things.

Emperor Trajan VIII, Roman Imperial Republic Battleship laid down 1905 (Engine 1928)

Displacement:
   15,484 t light; 16,447 t standard; 17,429 t normal; 18,215 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (465.88 ft / 459.32 ft) x 82.02 ft x (24.61 / 25.55 ft)
   (142.00 m / 140.00 m) x 25.00 m  x (7.50 / 7.79 m)

Armament:
      6 - 13.39" / 340 mm 40.0 cal guns - 1,377.89lbs / 625.00kg shells, 84 per gun
     Breech loading guns in turret on barbette mounts, 1928 Model
     3 x Twin mounts on centreline, evenly spread
      16 - 5.51" / 140 mm 55.0 cal guns - 85.98lbs / 39.00kg shells, 250 per gun
     Quick firing guns in casemate mounts, 1909 Model
     16 x Single mounts on sides, evenly spread
      4 - 3.54" / 90.0 mm 50.0 cal guns - 20.94lbs / 9.50kg shells, 250 per gun
     Anti-air guns in deck and hoist mounts, 1926 Model
     4 x Single mounts on sides, evenly spread
      4 raised mounts
      12 - 1.10" / 28.0 mm 55.0 cal guns - 0.72lbs / 0.33kg shells, 5,000 per gun
     Anti-air guns in deck mounts, 1926 Model
     3 x Quad mounts on centreline, evenly spread
      3 raised mounts
      10 - 0.30" / 7.5 mm 66.7 cal guns - 0.01lbs / 0.01kg shells, 15,000 per gun
     Machine guns in deck mounts, 1925 Model
     10 x Single mounts on sides, evenly spread
      10 raised mounts
      Weight of broadside 9,736 lbs / 4,416 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   11.8" / 300 mm   298.56 ft / 91.00 m   18.04 ft / 5.50 m
   Ends:   3.54" / 90 mm   160.73 ft / 48.99 m   9.84 ft / 3.00 m
   Upper:   4.72" / 120 mm   298.56 ft / 91.00 m   9.02 ft / 2.75 m
     Main Belt covers 100 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   13.4" / 340 mm   7.09" / 180 mm      11.0" / 280 mm
   2nd:   4.72" / 120 mm   1.97" / 50 mm      1.97" / 50 mm
   3rd:   0.20" / 5 mm         -         0.98" / 25 mm

   - Armoured deck - multiple decks:
   For and Aft decks: 3.35" / 85 mm
   Forecastle: 1.38" / 35 mm  Quarter deck: 1.38" / 35 mm

   - Conning towers: Forward 9.84" / 250 mm, Aft 0.00" / 0 mm

Machinery:
   Diesel Internal combustion generators,  and steam turbines
   Electric motors, 4 shafts, 16,000 ihp / 11,936 Kw = 18.17 kts
   Range 4,515nm at 14.00 kts
   Bunker at max displacement = 1,768 tons

Complement:
   757 - 985

Cost:
   £1.299 million / $5.197 million

Distribution of weights at normal displacement:
   Armament: 1,392 tons, 8.0 %
      - Guns: 1,392 tons, 8.0 %
   Armour: 6,969 tons, 40.0 %
      - Belts: 3,642 tons, 20.9 %
      - Armament: 1,570 tons, 9.0 %
      - Armour Deck: 1,614 tons, 9.3 %
      - Conning Tower: 143 tons, 0.8 %
   Machinery: 645 tons, 3.7 %
   Hull, fittings & equipment: 5,663 tons, 32.5 %
   Fuel, ammunition & stores: 1,945 tons, 11.2 %
   Miscellaneous weights: 815 tons, 4.7 %
      - Hull below water: 450 tons
      - Hull above water: 100 tons
      - On freeboard deck: 225 tons
      - Above deck: 40 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     38,451 lbs / 17,441 Kg = 32.1 x 13.4 " / 340 mm shells or 4.5 torpedoes
   Stability (Unstable if below 1.00): 1.36
   Metacentric height 6.4 ft / 1.9 m
   Roll period: 13.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.69
   Seaboat quality  (Average = 1.00): 1.95

Hull form characteristics:
   Hull has low quarterdeck ,
     a ram bow and a cruiser stern
   Block coefficient (normal/deep): 0.658 / 0.662
   Length to Beam Ratio: 5.60 : 1
   'Natural speed' for length: 21.43 kts
   Power going to wave formation at top speed: 45 %
   Trim (Max stability = 0, Max steadiness = 100): 36
   Bow angle (Positive = bow angles forward): 5.00 degrees
   Stern overhang: -4.92 ft / -1.50 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  21.33 ft / 6.50 m,  20.51 ft / 6.25 m
      - Forward deck:   30.00 %,  20.51 ft / 6.25 m,  20.51 ft / 6.25 m
      - Aft deck:   35.00 %,  20.51 ft / 6.25 m,  20.51 ft / 6.25 m
      - Quarter deck:   15.00 %,  11.48 ft / 3.50 m,  11.48 ft / 3.50 m
      - Average freeboard:      19.22 ft / 5.86 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 52.1 %
      - Above water (accommodation/working, high = better): 150.0 %
   Waterplane Area: 29,074 Square feet or 2,701 Square metres
   Displacement factor (Displacement / loading): 113 %
   Structure weight / hull surface area: 155 lbs/sq ft or 755 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.90
      - Longitudinal: 2.39
      - 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

Its late so I haven't costed it out. I'll play around with a reconstruction-level option later.

[Kaiser Kirk]

The lack of notes makes assessing a little harder :)

For a predread, fairly redoubtable.

I've been stripping off the end belts and replacing them
with lighter ones - low cost, frees some weight.

I really wonder what the MV of the 340 firing a 625kg shell is.

Curious what the 850tons of misc weight is.
For the Diesel and Turbo generators you'll need ~300,
FC will be 140, LR radio 25... lots of extra there
which could be laminated onto your armor deck.

Likewise you'll eventually need to include a description
of that new armor in the notes.

[snip]

Notes

16000 SHP (18 knt) - 645 Natural + 162 Electric + 226 Diesel = 1033t

Range to 4515@14knts (1768 Bunker) [+ 677 from Electric, +3,386 from Diesel, 8578 Full Range]

Refreshed/New 340L40 firing 625kg shell
Replace casemates with 140L55
Remove 75mm guns
Add 90mm AA
Add 28mm AA (one quad per turret top)
Add 7.5mm MMG
New Deck Armor (90mm main, 35mm ends)
Additional MISC weight

Costs:
Arms & Engines
Totaly new guns - 1.4BP, $2.8
Diesel Engines - .645BP, $1.29

Armor & Functional MISC
New Armored Decks - 1.62BP, $1.62
Functional MISC - .815BP, $0.815

Hull, fittings & Equipment
NONE

Fuel, Ammo
$0.9725

Total per ship: $7.50, 4.48BP
Total Program Cost: $15, 8.96BP

Not to shabby to refresh the MEDBAT with.

[snip]

First crack at the 1926 Heavy Destroyer. An update to the HFD-21 class, it trades a set of torpedo tubes for an additional 140mm gun. Slightly faster, longer legged, and updates AA to a single quad 28mm mount. As a trade-off for mounting a smaller number of fish, carries a more individually powerful 610mm torpedo in a single quad mount (a change I will make to the preceding designs).

HFD-26, Imperial Roman Republic Heavy Destoyer laid down 1926

Displacement:
   2,000 t light; 2,090 t standard; 2,381 t normal; 2,614 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (403.56 ft / 393.70 ft) x 37.07 ft x (13.45 / 14.35 ft)
   (123.00 m / 120.00 m) x 11.30 m  x (4.10 / 4.37 m)

Armament:
      5 - 5.51" / 140 mm 40.0 cal guns - 85.98lbs / 39.00kg shells, 140 per gun
     Quick firing guns in deck mounts, 1917 Model
     5 x Single mounts on centreline ends, majority aft
      3 raised mounts - superfiring
      4 - 1.10" / 28.0 mm 55.0 cal guns - 0.72lbs / 0.33kg shells, 5,000 per gun
     Anti-air guns in deck mount, 1926 Model
     1 x Quad mount on centreline, forward deck aft
      1 raised mount
      4 - 0.26" / 6.5 mm 110.0 cal guns - 0.01lbs / 0.00kg shells, 10,000 per gun
     Machine guns in deck mounts, 1926 Model
     4 x Single mounts on sides, evenly spread
      4 raised mounts
      Weight of broadside 433 lbs / 196 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.39" / 10 mm   0.20" / 5 mm            -
   2nd:   0.20" / 5 mm         -               -

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 4 shafts, 48,000 shp / 35,808 Kw = 33.49 kts
   Range 6,000nm at 14.00 kts
   Bunker at max displacement = 525 tons

Complement:
   169 - 221

Cost:
   £0.925 million / $3.702 million

Distribution of weights at normal displacement:
   Armament: 63 tons, 2.6 %
      - Guns: 63 tons, 2.6 %
   Armour: 8 tons, 0.3 %
      - Armament: 8 tons, 0.3 %
   Machinery: 1,290 tons, 54.2 %
   Hull, fittings & equipment: 560 tons, 23.5 %
   Fuel, ammunition & stores: 381 tons, 16.0 %
   Miscellaneous weights: 80 tons, 3.4 %
      - Hull below water: 20 tons
      - On freeboard deck: 60 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     614 lbs / 278 Kg = 7.3 x 5.5 " / 140 mm shells or 0.3 torpedoes
   Stability (Unstable if below 1.00): 1.54
   Metacentric height 2.3 ft / 0.7 m
   Roll period: 10.2 seconds
   Steadiness   - As gun platform (Average = 50 %): 51 %
         - Recoil effect (Restricted arc if above 1.00): 0.23
   Seaboat quality  (Average = 1.00): 1.04

Hull form characteristics:
   Hull has rise forward of midbreak,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.424 / 0.437
   Length to Beam Ratio: 10.62 : 1
   'Natural speed' for length: 19.84 kts
   Power going to wave formation at top speed: 64 %
   Trim (Max stability = 0, Max steadiness = 100): 49
   Bow angle (Positive = bow angles forward): 25.00 degrees
   Stern overhang: 0.30 ft / 0.09 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  20.51 ft / 6.25 m,  20.51 ft / 6.25 m
      - Forward deck:   17.50 %,  20.51 ft / 6.25 m,  20.51 ft / 6.25 m
      - Aft deck:   47.50 %,  11.48 ft / 3.50 m,  11.48 ft / 3.50 m
      - Quarter deck:   15.00 %,  11.48 ft / 3.50 m,  11.48 ft / 3.50 m
      - Average freeboard:      14.87 ft / 4.53 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 183.7 %
      - Above water (accommodation/working, high = better): 143.1 %
   Waterplane Area: 9,128 Square feet or 848 Square metres
   Displacement factor (Displacement / loading): 72 %
   Structure weight / hull surface area: 35 lbs/sq ft or 171 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.34
      - Overall: 0.56
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room

--20t 4x610mm (1918) Torpedo Tubes (1x4 mount centerline)
--6t 1918 FC
--25t LR Wireless
--15t 1915 Hydrophone
--14t Depth Charges
--3t DC Throwers
--3t Night Fighting Equipment
--5t Construction Reserve

[snip]

And their general counterpart. Updated GFD-21, full armament refresh, little faster and longer legged.

GFD-1926, Imperial Roman Republic Destroyer laid down 1926

Displacement:
   1,280 t light; 1,332 t standard; 1,549 t normal; 1,723 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (334.64 ft / 328.08 ft) x 29.53 ft x (10.66 / 11.58 ft)
   (102.00 m / 100.00 m) x 9.00 m  x (3.25 / 3.53 m)

Armament:
      4 - 3.54" / 90.0 mm 50.0 cal guns - 20.94lbs / 9.50kg shells, 175 per gun
     Quick firing guns in deck mounts, 1926 Model
     2 x Twin mounts on centreline ends, evenly spread
      2 - 2.24" / 57.0 mm 55.0 cal guns - 6.06lbs / 2.75kg shells, 750 per gun
     Anti-air guns in deck mount, 1926 Model
     1 x Twin mount on centreline, forward deck aft
      1 raised mount
      4 - 1.10" / 28.0 mm 55.0 cal guns - 0.72lbs / 0.33kg shells, 5,000 per gun
     Anti-air guns in deck mount, 1926 Model
     1 x Quad mount on centreline, aft deck aft
      1 raised mount
      Weight of broadside 99 lbs / 45 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.39" / 10 mm   0.20" / 5 mm            -
   2nd:   0.20" / 5 mm         -               -
   3rd:   0.20" / 5 mm         -               -

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 2 shafts, 30,000 shp / 22,380 Kw = 30.83 kts
   Range 5,750nm at 14.00 kts
   Bunker at max displacement = 391 tons

Complement:
   123 - 160

Cost:
   £0.554 million / $2.214 million

Distribution of weights at normal displacement:
   Armament: 19 tons, 1.3 %
      - Guns: 19 tons, 1.3 %
   Armour: 3 tons, 0.2 %
      - Armament: 3 tons, 0.2 %
   Machinery: 780 tons, 50.4 %
   Hull, fittings & equipment: 367 tons, 23.7 %
   Fuel, ammunition & stores: 269 tons, 17.4 %
   Miscellaneous weights: 110 tons, 7.1 %
      - Hull below water: 25 tons
      - Hull above water: 10 tons
      - On freeboard deck: 75 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     462 lbs / 210 Kg = 20.8 x 3.5 " / 90 mm shells or 0.3 torpedoes
   Stability (Unstable if below 1.00): 1.26
   Metacentric height 1.2 ft / 0.4 m
   Roll period: 11.2 seconds
   Steadiness   - As gun platform (Average = 50 %): 67 %
         - Recoil effect (Restricted arc if above 1.00): 0.14
   Seaboat quality  (Average = 1.00): 1.10

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.525 / 0.537
   Length to Beam Ratio: 11.11 : 1
   'Natural speed' for length: 18.11 kts
   Power going to wave formation at top speed: 67 %
   Trim (Max stability = 0, Max steadiness = 100): 61
   Bow angle (Positive = bow angles forward): 20.00 degrees
   Stern overhang: 0.89 ft / 0.27 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  15.58 ft / 4.75 m,  13.94 ft / 4.25 m
      - Forward deck:   30.00 %,  13.94 ft / 4.25 m,  13.94 ft / 4.25 m
      - Aft deck:   35.00 %,  13.94 ft / 4.25 m,  13.94 ft / 4.25 m
      - Quarter deck:   15.00 %,  13.94 ft / 4.25 m,  13.94 ft / 4.25 m
      - Average freeboard:      14.07 ft / 4.29 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 170.0 %
      - Above water (accommodation/working, high = better): 142.6 %
   Waterplane Area: 6,604 Square feet or 614 Square metres
   Displacement factor (Displacement / loading): 74 %
   Structure weight / hull surface area: 28 lbs/sq ft or 134 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.83
      - Overall: 0.57
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room

--20t 4x610mm (1918) Torpedo Tubes (1x4 mount cenerline)
--2t 1918 FC
--25t LR Wireless
--3t Night Fighting Equipment
--10t Construction Reserve
--15t 1915 Hydrophone
--20t Depth Charges
--5t DC Throwers
--5t ASW Paravane
--5t Minesweaping Paravane

[The Rock Doctor]

Those would be some big fish.

[snip]

A refurbishment of the Praeventores class battleships. The oldest class mounting the 340L45, this update stops short of a major reconstruction as the class has some issues with deck space due to its all-main-deck turrets. However, it is viewed that with updating these ships can serve as the heavy anchor of a station squadron, likely to be the fleet based out of Havana. Features a refreshed 340L45 to fire a Superheavy shell.

Praeventores, Imperial Roman Republic Battleship laid down 1909 (Engine 1927)

Displacement:
   25,468 t light; 27,090 t standard; 28,132 t normal; 28,966 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (633.20 ft / 623.36 ft) x 88.58 ft x (26.25 / 26.92 ft)
   (193.00 m / 190.00 m) x 27.00 m  x (8.00 / 8.20 m)

Armament:
      12 - 13.39" / 340 mm 45.0 cal guns - 1,450.64lbs / 658.00kg shells, 91 per gun
     Breech loading guns in turret on barbette mounts, 1927 Model
     4 x 3-gun mounts on centreline, evenly spread
      16 - 5.51" / 140 mm 55.0 cal guns - 85.98lbs / 39.00kg shells, 175 per gun
     Quick firing guns in casemate mounts, 1909 Model
     16 x Single mounts on sides, evenly spread
      16 hull mounts in casemates- Limited use in heavy seas
      4 - 3.54" / 90.0 mm 50.0 cal guns - 20.94lbs / 9.50kg shells, 250 per gun
     Anti-air guns in deck and hoist mounts, 1926 Model
     4 x Single mounts on sides, evenly spread
      4 raised mounts
      16 - 1.10" / 28.0 mm 55.0 cal guns - 0.72lbs / 0.33kg shells, 5,000 per gun
     Anti-air guns in deck mounts, 1926 Model
     4 x Quad mounts on centreline, evenly spread
      4 raised mounts
      10 - 0.30" / 7.5 mm 66.7 cal guns - 0.01lbs / 0.01kg shells, 15,000 per gun
     Machine guns in deck mounts, 1925 Model
     10 x Single mounts on sides, evenly spread
      10 raised mounts
      Weight of broadside 18,879 lbs / 8,563 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   12.6" / 320 mm   405.18 ft / 123.50 m   18.04 ft / 5.50 m
   Ends:   1.97" / 50 mm   218.14 ft / 66.49 m   9.84 ft / 3.00 m
   Upper:   1.97" / 50 mm   405.18 ft / 123.50 m   9.02 ft / 2.75 m
     Main Belt covers 100 % of normal length

   - Torpedo Bulkhead - Additional damage containing bulkheads:
      1.57" / 40 mm   405.18 ft / 123.50 m   26.25 ft / 8.00 m
   Beam between torpedo bulkheads 78.74 ft / 24.00 m

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   13.4" / 340 mm   7.09" / 180 mm      11.0" / 280 mm
   2nd:   3.94" / 100 mm   0.98" / 25 mm      1.97" / 50 mm
   3rd:   0.20" / 5 mm         -         0.98" / 25 mm
   4th:   0.20" / 5 mm         -               -

   - Armoured deck - multiple decks:
   For and Aft decks: 4.53" / 115 mm
   Forecastle: 1.38" / 35 mm  Quarter deck: 1.38" / 35 mm

   - Conning towers: Forward 9.84" / 250 mm, Aft 0.00" / 0 mm

Machinery:
   Oil fired boilers, steam turbines,
   Electric motors, 4 shafts, 36,000 shp / 26,856 Kw = 21.35 kts
   Range 4,448nm at 14.00 kts
   Bunker at max displacement = 1,876 tons

Complement:
   1,085 - 1,411

Cost:
   £2.500 million / $9.999 million

Distribution of weights at normal displacement:
   Armament: 3,402 tons, 12.1 %
      - Guns: 3,402 tons, 12.1 %
   Armour: 10,895 tons, 38.7 %
      - Belts: 4,473 tons, 15.9 %
      - Torpedo bulkhead: 620 tons, 2.2 %
      - Armament: 2,419 tons, 8.6 %
      - Armour Deck: 3,187 tons, 11.3 %
      - Conning Tower: 196 tons, 0.7 %
   Machinery: 1,136 tons, 4.0 %
   Hull, fittings & equipment: 8,945 tons, 31.8 %
   Fuel, ammunition & stores: 2,664 tons, 9.5 %
   Miscellaneous weights: 1,090 tons, 3.9 %
      - Hull below water: 500 tons
      - Hull above water: 100 tons
      - On freeboard deck: 450 tons
      - Above deck: 40 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     46,154 lbs / 20,935 Kg = 38.5 x 13.4 " / 340 mm shells or 7.2 torpedoes
   Stability (Unstable if below 1.00): 1.29
   Metacentric height 6.6 ft / 2.0 m
   Roll period: 14.5 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.78
   Seaboat quality  (Average = 1.00): 1.36

Hull form characteristics:
   Hull has low quarterdeck ,
     a ram bow and a cruiser stern
   Block coefficient (normal/deep): 0.679 / 0.682
   Length to Beam Ratio: 7.04 : 1
   'Natural speed' for length: 24.97 kts
   Power going to wave formation at top speed: 43 %
   Trim (Max stability = 0, Max steadiness = 100): 37
   Bow angle (Positive = bow angles forward): 10.00 degrees
   Stern overhang: 4.92 ft / 1.50 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  18.86 ft / 5.75 m,  18.86 ft / 5.75 m
      - Forward deck:   30.00 %,  18.86 ft / 5.75 m,  18.86 ft / 5.75 m
      - Aft deck:   35.00 %,  18.86 ft / 5.75 m,  18.86 ft / 5.75 m
      - Quarter deck:   15.00 %,  9.84 ft / 3.00 m,  9.84 ft / 3.00 m
      - Average freeboard:      17.51 ft / 5.34 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 70.9 %
      - Above water (accommodation/working, high = better): 143.9 %
   Waterplane Area: 43,447 Square feet or 4,036 Square metres
   Displacement factor (Displacement / loading): 100 %
   Structure weight / hull surface area: 182 lbs/sq ft or 889 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.97
      - Longitudinal: 1.30
      - Overall: 1.00
   Excellent machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Good seaboat, rides out heavy weather easily

New Engines: 1136t (+285t Electric Drives)

Range Recalculated to 4448@14knts

Refreshed 340/45 firing 658kg shell (reduced to 91rpg)
Remove 75mm guns
Add 90mm AA
Add 28mm AA (one quad per turret top)
Add 7.5mm MMG

New End and Upper Belts
New Decks

Trim Adjusted

Additional MISC weight (-285t Electric Drives)

Costs
Arms & Machinery
New Engines: 1.43BP/$2.86
New Guns: 3.41BP/$6.82

Armor & FMW
New End Belts: .156
New Upper Belts: .313
New Decks: 3.19
MISC Weight: 1.09

Hull, Fittings, & Equipment
Trim Change: 0BP/$5.1

Total Materials Costs: $19.53 / 9.59BP

Total Program Cost [Both ships] $49.26 / 19.18BP

[Kaiser Kirk]

please put in the design notes that the 15mm extra deck armor is laminated on, and if that's to the upper, the main, or a splinter deck.
It's not quite as good as solid deck armor.

Features a refreshed 340L45 to fire a Superheavy shell.

Commentary

1) You say 'refreshed' which I suppose means in 1926 & 1926.5 you'll research it.

That fits with my presumption has been upping the shell weight took a new gun.
Basically, precedent is the existing USN 16" couldn't fire the superheavies of the later USN 16".

2) Refreshing for you is quite doable.
It looks like you finish the 1920 artillery tech in 1925 HY2.
"For guns larger than 8.27"/210mm, it takes two years to research, at a cost of $0.50 per half-year."
But "Refreshing costs same as if the gun or mount was newly developed but the development time is halved.
So by 1927 it's quite possible to have finished researching a gun

3) What do you wind up with ?
Gun Research chart
The 1910 tech is 4200 for a 40 cal
Which oddly is the upper end of ME/Cal for this bore size.

Looks like you drop from 816mps to 742mps
The final MV for the new shell is only 10mps below the classic Brit 15", so not unreasonable,
Curious bit of math - looks like at 18000m, a target would move about 236m at 21knots in the ~2.25 sec time difference.

Will gain a bit in deck penetration, and the increased weight should give middling belt pen.
The USN 14"/45 had about the same KG and more MV, http://www.navweaps.com/Weapons/WNUS_14-45_mk1.php

ME	Bore	Shell wt max Cal.		Max Caliber	Caliber desired		MV	MPS
4200.0	135.8	1200.8		40.0	40.0		2644.8	816.3
4200.0	135.8	1450.6		40.0	40.0		2406.4	742.7

[snip]

The calculations include totally new deck armor, not a 15mm lamination onto the existing deck.

The 340mm guns in question are L45s, not L40s. The L40s are on the ETV and Invictas, which I dont think Im going to end up rebuilding. the 340L45 was originally created under the 1905 gun tech.

[snip]

First pass at the 1926 cruiser. Slight improvements over the preceding class, mainly in protection and non-primary armament.

GPC-26, Imperial Roman Republic Cruiser laid down 1926

Displacement:
   10,000 t light; 10,420 t standard; 11,675 t normal; 12,679 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (602.04 ft / 590.55 ft) x 63.98 ft x (21.33 / 22.71 ft)
   (183.50 m / 180.00 m) x 19.50 m  x (6.50 / 6.92 m)

Armament:
      8 - 7.09" / 180 mm 50.0 cal guns - 187.39lbs / 85.00kg shells, 150 per gun
     Breech loading guns in turret on barbette mounts, 1915 Model
     4 x 2-gun mounts on centreline ends, evenly spread
      2 raised mounts - superfiring
      4 - 5.51" / 140 mm 55.0 cal guns - 85.98lbs / 39.00kg shells, 175 per gun
     Quick firing guns in deck and hoist mounts, 1926 Model
     2 x Twin mounts on sides, forward deck aft
      4 - 3.54" / 90.0 mm 50.0 cal guns - 20.94lbs / 9.50kg shells, 250 per gun
     Anti-air guns in deck and hoist mounts, 1926 Model
     4 x Single mounts on sides, evenly spread
      4 raised mounts
      8 - 1.10" / 28.0 mm 55.0 cal guns - 0.72lbs / 0.33kg shells, 5,000 per gun
     Anti-air guns in deck and hoist mounts, 1926 Model
     2 x Quad mounts on sides, aft deck centre
      2 raised mounts
      Weight of broadside 1,933 lbs / 877 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   3.94" / 100 mm   398.26 ft / 121.39 m   16.40 ft / 5.00 m
   Ends:   Unarmoured
     Main Belt covers 104 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   2.36" / 60 mm   1.18" / 30 mm      2.36" / 60 mm
   2nd:   0.98" / 25 mm   0.59" / 15 mm      1.97" / 50 mm
   3rd:   0.20" / 5 mm         -         0.59" / 15 mm
   4th:         -            -         0.59" / 15 mm

   - Armoured deck - single deck:
   For and Aft decks: 1.38" / 35 mm
   Forecastle: 0.00" / 0 mm  Quarter deck: 1.38" / 35 mm

   - Conning towers: Forward 2.76" / 70 mm, Aft 0.00" / 0 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 4 shafts, 92,000 shp / 68,632 Kw = 31.80 kts
   Range 10,000nm at 14.00 kts
   Bunker at max displacement = 2,260 tons

Complement:
   561 - 730

Cost:
   £3.361 million / $13.446 million

Distribution of weights at normal displacement:
   Armament: 600 tons, 5.1 %
      - Guns: 600 tons, 5.1 %
   Armour: 1,910 tons, 16.4 %
      - Belts: 1,057 tons, 9.1 %
      - Armament: 220 tons, 1.9 %
      - Armour Deck: 602 tons, 5.2 %
      - Conning Tower: 31 tons, 0.3 %
   Machinery: 2,945 tons, 25.2 %
   Hull, fittings & equipment: 4,171 tons, 35.7 %
   Fuel, ammunition & stores: 1,675 tons, 14.3 %
   Miscellaneous weights: 375 tons, 3.2 %
      - Hull below water: 80 tons
      - Hull above water: 100 tons
      - On freeboard deck: 170 tons
      - Above deck: 25 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     14,909 lbs / 6,763 Kg = 83.8 x 7.1 " / 180 mm shells or 1.7 torpedoes
   Stability (Unstable if below 1.00): 1.22
   Metacentric height 3.7 ft / 1.1 m
   Roll period: 14.0 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.43
   Seaboat quality  (Average = 1.00): 1.17

Hull form characteristics:
   Hull has rise forward of midbreak,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.507 / 0.517
   Length to Beam Ratio: 9.23 : 1
   'Natural speed' for length: 24.30 kts
   Power going to wave formation at top speed: 57 %
   Trim (Max stability = 0, Max steadiness = 100): 43
   Bow angle (Positive = bow angles forward): 20.00 degrees
   Stern overhang: 1.64 ft / 0.50 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   18.00 %,  27.07 ft / 8.25 m,  25.43 ft / 7.75 m
      - Forward deck:   40.00 %,  25.43 ft / 7.75 m,  25.43 ft / 7.75 m
      - Aft deck:   27.44 %,  16.40 ft / 5.00 m,  16.40 ft / 5.00 m
      - Quarter deck:   14.56 %,  16.40 ft / 5.00 m,  16.40 ft / 5.00 m
      - Average freeboard:      21.76 ft / 6.63 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 100.6 %
      - Above water (accommodation/working, high = better): 187.1 %
   Waterplane Area: 25,333 Square feet or 2,354 Square metres
   Displacement factor (Displacement / loading): 115 %
   Structure weight / hull surface area: 110 lbs/sq ft or 537 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.94
      - Longitudinal: 1.61
      - Overall: 1.00
   Adequate machinery, storage, compartmentation space
   Excellent accommodation and workspace room

[Kaiser Kirk]

The 340mm guns in question are L45s, not L40s. The L40s are on the ETV and Invictas, which I dont think Im going to end up rebuilding. the 340L45 was originally created under the 1905 gun tech.

Well whoops, messed that one up.
Looks like the MV for the refreshed gun should be ~786mps, pretty decent.

As for the deck, bad presumption on my part, I choose the cheaper route because...I'm cheap. :)

[snip]

Looking at an addition to the auxiliary forces, a leader for the various 500t sloops. Haven't fully noodled the MISC weight yet.

LSL-26, Imperial Roman Republic Large Sloop, Leader laid down 1926

Displacement:
   2,000 t light; 2,099 t standard; 2,503 t normal; 2,826 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (301.84 ft / 295.28 ft) x 41.83 ft x (14.76 / 16.16 ft)
   (92.00 m / 90.00 m) x 12.75 m  x (4.50 / 4.93 m)

Armament:
      3 - 5.51" / 140 mm 40.0 cal guns - 85.98lbs / 39.00kg shells, 250 per gun
     Quick firing guns in deck and hoist mounts, 1917 Model
     3 x Single mounts on centreline ends, majority forward
      1 raised mount - superfiring
      2 - 2.24" / 57.0 mm 43.0 cal guns - 5.52lbs / 2.50kg shells, 750 per gun
     Anti-air guns in deck and hoist mount, 1926 Model
     1 x Twin mount on centreline, aft deck forward
      1 raised mount
      4 - 1.10" / 28.0 mm 55.0 cal guns - 0.72lbs / 0.33kg shells, 5,000 per gun
     Anti-air guns in deck mount, 1926 Model
     1 x Quad mount on centreline, aft deck aft
      1 raised mount
      6 - 0.30" / 7.5 mm 66.7 cal guns - 0.01lbs / 0.01kg shells, 15,000 per gun
     Machine guns in deck mounts, 1925 Model
     6 x Single mounts on sides, evenly spread
      6 raised mounts
      Weight of broadside 272 lbs / 123 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.39" / 10 mm   0.20" / 5 mm      0.79" / 20 mm
   2nd:   0.20" / 5 mm         -         0.79" / 20 mm

   - Protected deck - single deck:
   For and Aft decks: 1.97" / 50 mm
   Forecastle: 1.38" / 35 mm  Quarter deck: 1.38" / 35 mm

   - Conning towers: Forward 1.97" / 50 mm, Aft 0.00" / 0 mm

Machinery:
   Diesel Internal combustion generators,
   Electric motors, 2 shafts, 4,000 shp / 2,984 Kw = 17.05 kts
   Range 8,000nm at 14.00 kts
   Bunker at max displacement = 727 tons

Complement:
   176 - 230

Cost:
   £0.379 million / $1.516 million

Distribution of weights at normal displacement:
   Armament: 61 tons, 2.4 %
      - Guns: 61 tons, 2.4 %
   Armour: 294 tons, 11.7 %
      - Armament: 5 tons, 0.2 %
      - Armour Deck: 280 tons, 11.2 %
      - Conning Tower: 8 tons, 0.3 %
   Machinery: 128 tons, 5.1 %
   Hull, fittings & equipment: 717 tons, 28.7 %
   Fuel, ammunition & stores: 503 tons, 20.1 %
   Miscellaneous weights: 800 tons, 32.0 %
      - Hull below water: 150 tons
      - Hull above water: 300 tons
      - On freeboard deck: 300 tons
      - Above deck: 50 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     5,911 lbs / 2,681 Kg = 70.6 x 5.5 " / 140 mm shells or 2.2 torpedoes
   Stability (Unstable if below 1.00): 1.22
   Metacentric height 1.9 ft / 0.6 m
   Roll period: 12.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.22
   Seaboat quality  (Average = 1.00): 1.83

Hull form characteristics:
   Hull has rise forward of midbreak,
     a normal bow and a round stern
   Block coefficient (normal/deep): 0.480 / 0.495
   Length to Beam Ratio: 7.06 : 1
   'Natural speed' for length: 17.18 kts
   Power going to wave formation at top speed: 45 %
   Trim (Max stability = 0, Max steadiness = 100): 38
   Bow angle (Positive = bow angles forward): 15.00 degrees
   Stern overhang: 2.17 ft / 0.66 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  16.40 ft / 5.00 m,  16.40 ft / 5.00 m
      - Forward deck:   25.00 %,  16.40 ft / 5.00 m,  16.40 ft / 5.00 m
      - Aft deck:   40.00 %,  7.38 ft / 2.25 m,  7.38 ft / 2.25 m
      - Quarter deck:   15.00 %,  7.38 ft / 2.25 m,  7.38 ft / 2.25 m
      - Average freeboard:      11.44 ft / 3.49 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 46.7 %
      - Above water (accommodation/working, high = better): 95.0 %
   Waterplane Area: 8,086 Square feet or 751 Square metres
   Displacement factor (Displacement / loading): 161 %
   Structure weight / hull surface area: 60 lbs/sq ft or 292 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.93
      - Longitudinal: 1.98
      - Overall: 1.00
   Excellent 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

[snip]

And the new 500t design.

SL-26, Imperial Roman Republic Sloop laid down 1926

Displacement:
   486 t light; 502 t standard; 600 t normal; 679 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (232.41 ft / 229.66 ft) x 26.25 ft x (8.20 / 8.93 ft)
   (70.84 m / 70.00 m) x 8.00 m  x (2.50 / 2.72 m)

Armament:
      1 - 3.54" / 90.0 mm 50.0 cal gun - 20.94lbs / 9.50kg shells, 75 per gun
     Quick firing gun in deck mount, 1926 Model
     1 x Single mount on centreline, forward deck forward
      4 - 1.10" / 28.0 mm 55.0 cal guns - 0.72lbs / 0.33kg shells, 1,500 per gun
     Anti-air guns in deck mount, 1926 Model
     1 x Quad mount on centreline, aft deck aft
      1 raised mount
      Weight of broadside 24 lbs / 11 kg

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.39" / 10 mm   0.20" / 5 mm            -

Machinery:
   Diesel Internal combustion generators,
   Electric motors, 2 shafts, 3,600 shp / 2,686 Kw = 20.57 kts
   Range 4,500nm at 14.00 kts
   Bunker at max displacement = 177 tons

Complement:
   59 - 78

Cost:
   £0.120 million / $0.480 million

Distribution of weights at normal displacement:
   Armament: 6 tons, 1.0 %
      - Guns: 6 tons, 1.0 %
   Armour: 1 tons, 0.2 %
      - Armament: 1 tons, 0.2 %
   Machinery: 115 tons, 19.2 %
   Hull, fittings & equipment: 224 tons, 37.4 %
   Fuel, ammunition & stores: 114 tons, 18.9 %
   Miscellaneous weights: 140 tons, 23.3 %
      - Hull below water: 30 tons
      - Hull above water: 25 tons
      - On freeboard deck: 70 tons
      - Above deck: 15 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     1,105 lbs / 501 Kg = 49.7 x 3.5 " / 90 mm shells or 0.7 torpedoes
   Stability (Unstable if below 1.00): 1.16
   Metacentric height 0.9 ft / 0.3 m
   Roll period: 11.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.05
   Seaboat quality  (Average = 1.00): 1.50

Hull form characteristics:
   Hull has rise forward of midbreak,
     a normal bow and a round stern
   Block coefficient (normal/deep): 0.425 / 0.441
   Length to Beam Ratio: 8.75 : 1
   'Natural speed' for length: 15.15 kts
   Power going to wave formation at top speed: 55 %
   Trim (Max stability = 0, Max steadiness = 100): 47
   Bow angle (Positive = bow angles forward): 10.00 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 %,  15.58 ft / 4.75 m,  15.58 ft / 4.75 m
      - Forward deck:   17.00 %,  15.58 ft / 4.75 m,  15.58 ft / 4.75 m
      - Aft deck:   48.00 %,  6.56 ft / 2.00 m,  6.56 ft / 2.00 m
      - Quarter deck:   15.00 %,  6.56 ft / 2.00 m,  6.56 ft / 2.00 m
      - Average freeboard:      9.90 ft / 3.02 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 75.9 %
      - Above water (accommodation/working, high = better): 108.6 %
   Waterplane Area: 3,771 Square feet or 350 Square metres
   Displacement factor (Displacement / loading): 155 %
   Structure weight / hull surface area: 35 lbs/sq ft or 170 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.91
      - Longitudinal: 2.30
      - Overall: 1.00
   Excellent machinery, storage, compartmentation space
   Adequate accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform
   Good seaboat, rides out heavy weather easily