Harbour/River patrol vessels

[Sachmle]

P-100 Class, NUS Patrolboat laid down 1908 (Engine 1905)

Displacement:
   245 t light; 252 t standard; 262 t normal; 271 t full load

Dimensions: Length overall / water x beam x draught
   158.74 ft / 155.00 ft x 18.00 ft x 8.00 ft (normal load)
   48.38 m / 47.24 m x 5.49 m  x 2.44 m

Armament:
     1 - 2.00" / 50.8 mm guns in single mounts, 4.00lbs / 1.81kg shells, 1905 Model
     Quick firing gun in deck mount
     on centreline forward
     6 - 0.98" / 25.0 mm guns in single mounts, 0.48lbs / 0.22kg shells, 1905 Model
     Machine guns in deck mounts
     on side, evenly spread
   Weight of broadside 7 lbs / 3 kg
   Shells per gun, main battery: 200
   2 - 18.0" / 457.2 mm above water torpedoes

Armour:
  - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.25" / 6 mm         -               -

  - Conning tower: 0.50" / 13 mm

Machinery:
   Coal fired boilers, steam turbines,
   Direct drive, 2 shafts, 6,015 shp / 4,487 Kw = 25.00 kts
   Range 335nm at 12.00 kts
   Bunker at max displacement = 19 tons (100% coal)
     Caution: Delicate, lightweight machinery

Complement:
   32 - 42

Cost:
   £0.031 million / $0.122 million

Distribution of weights at normal displacement:
   Armament: 1 tons, 0.3 %
   Armour: 1 tons, 0.3 %
      - Belts: 0 tons, 0.0 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 0 tons, 0.1 %
      - Armour Deck: 0 tons, 0.0 %
      - Conning Tower: 0 tons, 0.2 %
   Machinery: 152 tons, 57.8 %
   Hull, fittings & equipment: 82 tons, 31.3 %
   Fuel, ammunition & stores: 17 tons, 6.4 %
   Miscellaneous weights: 10 tons, 3.8 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     61 lbs / 28 Kg = 15.2 x 2.0 " / 51 mm shells or 0.1 torpedoes
   Stability (Unstable if below 1.00): 1.05
   Metacentric height 0.4 ft / 0.1 m
   Roll period: 11.7 seconds
   Steadiness   - As gun platform (Average = 50 %): 71 %
         - Recoil effect (Restricted arc if above 1.00): 0.06
   Seaboat quality  (Average = 1.00): 1.09

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.411
   Length to Beam Ratio: 8.61 : 1
   'Natural speed' for length: 12.45 kts
   Power going to wave formation at top speed: 73 %
   Trim (Max stability = 0, Max steadiness = 100): 65
   Bow angle (Positive = bow angles forward): 14.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      15.00 ft / 4.57 m
      - Forecastle (30 %):   15.00 ft / 4.57 m
      - Mid (40 %):      15.00 ft / 4.57 m (7.00 ft / 2.13 m aft of break)
      - Quarterdeck (20 %):   7.00 ft / 2.13 m
      - Stern:      7.00 ft / 2.13 m
      - Average freeboard:   10.20 ft / 3.11 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 193.5 %
      - Above water (accommodation/working, high = better): 56.4 %
   Waterplane Area: 1,729 Square feet or 161 Square metres
   Displacement factor (Displacement / loading): 26 %
   Structure weight / hull surface area: 18 lbs/sq ft or 87 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 7.07
      - Overall: 0.65
   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