Murmuro Class Fast Minelayer

Started by snip, September 13, 2022, 11:00:18 PM

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snip

Two Ships
--IRS Murmuro
--IRS Crispico

QuoteMurmuro, Imperial Roman Fast Mine Crusier laid down 1914

Displacement:
   3,238 t light; 3,324 t standard; 3,750 t normal; 4,091 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (410.09 ft / 400.26 ft) x 40.19 ft x (14.76 / 15.82 ft)
   (125.00 m / 122.00 m) x 12.25 m  x (4.50 / 4.82 m)

Armament:
      4 - 3.94" / 100 mm 45.0 cal guns - 30.86lbs / 14.00kg shells, 150 per gun
     Quick firing guns in deck mounts, 1906 Model
     2 x Twin mounts on centreline, forward evenly spread
      2 - 1.77" / 45.0 mm 50.0 cal guns - 3.31lbs / 1.50kg shells, 250 per gun
     Quick firing guns in deck mounts, 1905 Model
     2 x Single mounts on centreline, aft evenly spread
      2 raised mounts
      Weight of broadside 130 lbs / 59 kg

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

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 2 shafts, 50,000 shp / 37,300 Kw = 31.04 kts
   Range 5,000nm at 14.00 kts
   Bunker at max displacement = 767 tons

Complement:
   239 - 311

Cost:
   £0.488 million / $1.950 million

Distribution of weights at normal displacement:
   Armament: 20 tons, 0.5 %
      - Guns: 20 tons, 0.5 %
   Armour: 2 tons, 0.0 %
      - Armament: 2 tons, 0.0 %
   Machinery: 1,882 tons, 50.2 %
   Hull, fittings & equipment: 1,134 tons, 30.2 %
   Fuel, ammunition & stores: 512 tons, 13.7 %
   Miscellaneous weights: 200 tons, 5.3 %
      - On freeboard deck: 200 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     1,735 lbs / 787 Kg = 56.9 x 3.9 " / 100 mm shells or 0.5 torpedoes
   Stability (Unstable if below 1.00): 1.38
   Metacentric height 2.2 ft / 0.7 m
   Roll period: 11.3 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.05
   Seaboat quality  (Average = 1.00): 1.00

Hull form characteristics:
   Hull has rise forward of midbreak,
     a normal bow and a round stern
   Block coefficient (normal/deep): 0.553 / 0.562
   Length to Beam Ratio: 9.96 : 1
   'Natural speed' for length: 20.01 kts
   Power going to wave formation at top speed: 66 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 20.00 degrees
   Stern overhang: 2.07 ft / 0.63 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
      - Forecastle:   20.00 %,  21.33 ft / 6.50 m,  21.33 ft / 6.50 m
      - Forward deck:   25.00 %,  21.33 ft / 6.50 m,  21.33 ft / 6.50 m
      - Aft deck:   40.00 %,  12.30 ft / 3.75 m,  12.30 ft / 3.75 m
      - Quarter deck:   15.00 %,  12.30 ft / 3.75 m,  12.30 ft / 3.75 m
      - Average freeboard:      16.36 ft / 4.99 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 164.0 %
      - Above water (accommodation/working, high = better): 141.5 %
   Waterplane Area: 11,258 Square feet or 1,046 Square metres
   Displacement factor (Displacement / loading): 91 %
   Structure weight / hull surface area: 56 lbs/sq ft or 271 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.83
      - Longitudinal: 1.95
      - Overall: 0.90
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room

Misc Distribution
--On Deck (200t)
----150t Mines
----25t LR Wireless
----10t SR Wireless
----10t Additional Mine Handling equipment
----2t 1912 FC
----3t Construction Reserve
You smug-faced crowds with kindling eye
Who cheer when solider lads march by
Sneak home and pray that you'll never know
The hell where youth and laughter go.
-Siegfried Sassoon

snip

In 1922H2, both ships were updated to 1918 Fire Control.
You smug-faced crowds with kindling eye
Who cheer when solider lads march by
Sneak home and pray that you'll never know
The hell where youth and laughter go.
-Siegfried Sassoon