Minesweeper concept

[Valles]

MS-1917, Maori Minesweeper laid down 1912

Displacement:
   333 t light; 344 t standard; 502 t normal; 629 t full load

Dimensions: Length overall / water x beam x draught
   195.00 ft / 190.29 ft x 19.69 ft x 9.84 ft (normal load)
   59.44 m / 58.00 m x 6.00 m  x 3.00 m

Armament:
      1 - 2.95" / 75.0 mm guns in single mounts, 13.23lbs / 6.00kg shells, 1912 Model
     Quick firing gun in a deck mount with hoist
     on centreline aft
   Weight of broadside 13 lbs / 6 kg
   Shells per gun, main battery: 200

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

Machinery:
   Oil fired boilers, complex reciprocating steam engines,
   Electric motors, 2 shafts, 2,077 ihp / 1,549 Kw = 18.00 kts
   Range 5,000nm at 14.00 kts
   Bunker at max displacement = 284 tons

Complement:
   52 - 68

Cost:
   £0.031 million / $0.122 million

Distribution of weights at normal displacement:
   Armament: 2 tons, 0.3 %
   Armour: 1 tons, 0.2 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 1 tons, 0.2 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.0 %
   Machinery: 125 tons, 24.9 %
   Hull, fittings & equipment: 180 tons, 35.9 %
   Fuel, ammunition & stores: 170 tons, 33.7 %
   Miscellaneous weights: 25 tons, 5.0 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     746 lbs / 338 Kg = 58.0 x 3.0 " / 75 mm shells or 0.5 torpedoes
   Stability (Unstable if below 1.00): 1.27
   Metacentric height 0.7 ft / 0.2 m
   Roll period: 10.1 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.12
   Seaboat quality  (Average = 1.00): 2.00

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.477
   Length to Beam Ratio: 9.67 : 1
   'Natural speed' for length: 13.79 kts
   Power going to wave formation at top speed: 54 %
   Trim (Max stability = 0, Max steadiness = 100): 35
   Bow angle (Positive = bow angles forward): 5.00 degrees
   Stern overhang: 3.28 ft / 1.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      16.40 ft / 5.00 m
      - Forecastle (15 %):   16.40 ft / 5.00 m
      - Mid (28 %):      16.40 ft / 5.00 m (8.20 ft / 2.50 m aft of break)
      - Quarterdeck (15 %):   8.20 ft / 2.50 m
      - Stern:      8.20 ft / 2.50 m
      - Average freeboard:   10.50 ft / 3.20 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 89.3 %
      - Above water (accommodation/working, high = better): 87.1 %
   Waterplane Area: 2,445 Square feet or 227 Square metres
   Displacement factor (Displacement / loading): 174 %
   Structure weight / hull surface area: 29 lbs/sq ft or 143 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.82
      - Longitudinal: 5.94
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is cramped
   Ship has slow, easy roll, a good, steady gun platform
   Excellent seaboat, comfortable, can fire her guns in the heaviest weather

25 tons paravanes and other sweeping gear

333t/Light = 3/BP x4 for merchant construction = 12/BP