Messana Class Cruisers

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Five Ships

--IRS Messana
--IRS Havre-de-Grâce
--IRS Montpelhièr
--IRS Dubris
--IRS Santa Rochelle

GPC-21A-3, Imperial Roman Republic Cruiser laid down 1921

Displacement:
   9,000 t light; 9,343 t standard; 10,581 t normal; 11,571 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (569.23 ft / 557.74 ft) x 63.98 ft x (21.33 / 22.80 ft)
   (173.50 m / 170.00 m) x 19.50 m  x (6.50 / 6.95 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
      2 - 3.94" / 100 mm 45.0 cal guns - 30.86lbs / 14.00kg shells, 175 per gun
     Anti-air guns in deck mounts, 1917 Model
     2 x Single mounts on sides, forward deck aft
      2 raised mounts
      6 - 0.26" / 6.5 mm 110.0 cal guns - 0.01lbs / 0.00kg shells, 15,000 per gun
     Machine guns in deck mounts, 1911 Model
     6 x Single mounts on sides, forward evenly spread
      6 raised mounts
      Weight of broadside 1,561 lbs / 708 kg

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   3.15" / 80 mm   376.15 ft / 114.65 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:   0.20" / 5 mm         -               -
   3rd:   0.20" / 5 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 3.94" / 100 mm, Aft 0.00" / 0 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 4 shafts, 80,000 shp / 59,680 Kw = 31.02 kts
   Range 10,000nm at 14.00 kts
   Bunker at max displacement = 2,228 tons

Complement:
   521 - 678

Cost:
   £2.192 million / $8.769 million

Distribution of weights at normal displacement:
   Armament: 484 tons, 4.6 %
      - Guns: 484 tons, 4.6 %
   Armour: 1,613 tons, 15.2 %
      - Belts: 802 tons, 7.6 %
      - Armament: 212 tons, 2.0 %
      - Armour Deck: 558 tons, 5.3 %
      - Conning Tower: 41 tons, 0.4 %
   Machinery: 2,755 tons, 26.0 %
   Hull, fittings & equipment: 3,773 tons, 35.7 %
   Fuel, ammunition & stores: 1,581 tons, 14.9 %
   Miscellaneous weights: 375 tons, 3.5 %
      - 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):
     13,964 lbs / 6,334 Kg = 78.5 x 7.1 " / 180 mm shells or 1.6 torpedoes
   Stability (Unstable if below 1.00): 1.26
   Metacentric height 3.9 ft / 1.2 m
   Roll period: 13.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.34
   Seaboat quality  (Average = 1.00): 1.22

Hull form characteristics:
   Hull has rise forward of midbreak,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.487 / 0.498
   Length to Beam Ratio: 8.72 : 1
   'Natural speed' for length: 23.62 kts
   Power going to wave formation at top speed: 58 %
   Trim (Max stability = 0, Max steadiness = 100): 41
   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): 100.7 %
      - Above water (accommodation/working, high = better): 186.8 %
   Waterplane Area: 23,489 Square feet or 2,182 Square metres
   Displacement factor (Displacement / loading): 117 %
   Structure weight / hull surface area: 106 lbs/sq ft or 518 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.94
      - Longitudinal: 1.80
      - Overall: 1.00
   Adequate machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Good seaboat, rides out heavy weather easily

Misc Weight Distribution
-Below Water (80t)
--30t Additional Pumps
--30t Additional Damage Control Equipment
--10t Improved Food & Drink storage
-Above Water (100t)
--30t Additional Damage Control Equipment
--20t Enhanced Ventilation and Crew Comfort
--50t Long Range Wireless (2x)
-On Deck (170t)
--50t 1918 Fire Control
--50t Reserved for Future Aviation Facilities (2x Recon Plane & 2x Catapults)
--32t 8x530mm (1913) Torpedo Tubes (2x4 mounts Aft Deck Forward)
--25t Enhanced Ventilation and Crew Comfort
--10t Short Range Wireless
--3t Construction Reserve
-Above Deck (25t)
--10t Additional Optical Spotting Equipment
--10t Night Fighting Equipment
--5t Improved Signaling Equipment