Flota polska w XIX w. - korweta centralnobateryjna

Uzupełnieniem dla niedawno zbudowanych fregat z artylerią gwintowaną jest para nieco mniejszych korwet, również uzbrojonych w gwintowane, odtylcowe działa kal. 203 mm, choć oczywiście w mniejszej ilości. Nowe korwety są okrętami centralnobateryjnymi, co jest cechą raczej niespotykaną wśród jednostek nieopancerzonych, i dzięki temu, mimo małych rozmiarów niosą one stosunkowo ciężkie działa (ówcześnie budowane korwety niemieckie miały co najwyżej działa 150 mm, względnie 170mm – ale to już w drugiej połowie lat 70-tych). 

Porewit, polish corvette laid down 1869 (Engine 1870)

Displacement:
    1 341 t light; 1 421 t standard; 1 656 t normal; 1 844 t full load

Dimensions: Length overall / water x beam x draught
    189,37 ft / 187,86 ft x 36,88 ft x 15,32 ft (normal load)
    57,72 m / 57,26 m x 11,24 m  x 4,67 m

Armament:
      4 - 7,99" / 203 mm guns in single mounts, 174,84lbs / 79,31kg shells, 1869 Model
      Breech loading guns in broadside mounts
      on side, all amidships
    Weight of broadside 699 lbs / 317 kg
    Shells per gun, main battery: 120

Machinery:
    Coal fired boilers, simple reciprocating steam engines,
    Direct drive, 1 shaft, 2 003 ihp / 1 494 Kw = 13,80 kts
    Range 2 700nm at 9,00 kts
    Bunker at max displacement = 423 tons (100% coal)

Complement:
    246

Cost:
    £0,185 million / $0,740 million

Distribution of weights at normal displacement:
    Armament: 87 tons, 5,3%
    Machinery: 461 tons, 27,8%
    Hull, fittings & equipment: 655 tons, 39,6%
    Fuel, ammunition & stores: 315 tons, 19,0%
    Miscellaneous weights: 138 tons, 8,3%

Overall survivability and seakeeping ability:
    Survivability (Non-critical penetrating hits needed to sink ship):
      671 lbs / 305 Kg = 3,8 x 8,0 " / 203 mm shells or 0,3 torpedoes
    Stability (Unstable if below 1.00): 1,27
    Metacentric height 1,7 ft / 0,5 m
    Roll period: 11,8 seconds
    Steadiness    - As gun platform (Average = 50 %): 100 %
            - Recoil effect (Restricted arc if above 1.00): 0,56
    Seaboat quality  (Average = 1.00): 2,00

Hull form characteristics:
    Hull has a flush deck
    Block coefficient: 0,546
    Length to Beam Ratio: 5,09 : 1
    'Natural speed' for length: 13,71 kts
    Power going to wave formation at top speed: 53 %
    Trim (Max stability = 0, Max steadiness = 100): 50
    Bow angle (Positive = bow angles forward): -25,00 degrees
    Stern overhang: 1,51 ft / 0,46 m
    Freeboard (% = measuring location as a percentage of overall length):
       - Stem:        12,99 ft / 3,96 m
       - Forecastle (23%):    12,99 ft / 3,96 m
       - Mid (50%):        12,50 ft / 3,81 m
       - Quarterdeck (19%):    12,99 ft / 3,96 m
       - Stern:        12,99 ft / 3,96 m
       - Average freeboard:    12,85 ft / 3,92 m
    Ship tends to be wet forward

Ship space, strength and comments:
    Space    - Hull below water (magazines/engines, low = better): 138,8%
        - Above water (accommodation/working, high = better): 87,9%
    Waterplane Area: 4 668 Square feet or 434 Square metres
    Displacement factor (Displacement / loading): 91%
    Structure weight / hull surface area: 80 lbs/sq ft or 389 Kg/sq metre
    Hull strength (Relative):
        - Cross-sectional: 0,84
        - Longitudinal: 5,13
        - Overall: 1,00
    Hull space for machinery, storage, compartmentation is cramped
    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

Porewit (1870)
Jarowit (1871)