Porpoise, US Submarine laid down 1936
Displacement:
1,090 t light; 1,122 t standard; 1,262 t normal; 1,374 t full load
Dimensions: Length overall / water x beam x draught
227.00 ft / 227.00 ft x 20.00 ft (Bulges 23.50 ft) x 18.00 ft (normal load)
69.19 m / 69.19 m x 6.10 m (Bulges 7.16 m) x 5.49 m
Armament:
1 - 4.00" / 102 mm guns in single mounts, 33.00lbs / 14.97kg shells, 1936 Model
Quick firing gun in deck mount
on centreline forward
2 - 1.10" / 27.9 mm guns (1x2 guns), 0.92lbs / 0.42kg shells, 1936 Model
Anti-aircraft guns in deck mount
on centreline aft
2 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1936 Model
Machine guns in deck mounts
on centreline, all amidships, all raised mounts - superfiring
Weight of broadside 35 lbs / 16 kg
Shells per gun, main battery: 300
8 - 21.0" / 533.4 mm submerged torpedo tubes
Machinery:
Diesel Internal combustion generators plus batteries,
Electric motors, 2 shafts, 5,323 shp / 3,971 Kw = 20.00 kts
Range 9,600nm at 10.00 kts
Bunker at max displacement = 252 tons
Complement:
105 - 137
Cost:
£0.330 million / $1.320 million
Distribution of weights at normal displacement:
Armament: 4 tons, 0.3 %
Machinery: 149 tons, 11.8 %
Hull, fittings & equipment: 716 tons, 56.7 %
Fuel, ammunition & stores: 172 tons, 13.6 %
Miscellaneous weights: 221 tons, 17.5 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
231 lbs / 105 Kg = 7.2 x 4.0 " / 102 mm shells or 0.2 torpedoes
Stability (Unstable if below 1.00): 1.01
Metacentric height 0.5 ft / 0.1 m
Roll period: 14.7 seconds
Steadiness - As gun platform (Average = 50 %): 0 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 0.00
Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.460
Length to Beam Ratio: 9.66 : 1
'Natural speed' for length: 15.07 kts
Power going to wave formation at top speed: 54 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 0.00 ft / 0.00 m
- Forecastle (20 %): 0.00 ft / 0.00 m
- Mid (50 %): 0.00 ft / 0.00 m
- Quarterdeck (15 %): 0.00 ft / 0.00 m
- Stern: 0.00 ft / 0.00 m
- Average freeboard: 0.00 ft / 0.00 m
Ship tends to be wet forward
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 165.6 %
- Above water (accommodation/working, high = better): 0.0 %
Waterplane Area: 2,920 Square feet or 271 Square metres
Displacement factor (Displacement / loading): 228 %
Structure weight / hull surface area: 130 lbs/sq ft or 635 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 3.59
- Longitudinal: 3.02
- Overall: 3.15
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is extremely poor
Ship has quick, lively roll, not a steady gun platform
Caution: Lacks seaworthiness - very limited seakeeping ability
6 tubes are forward, 2 aft. 10 reload torpedoes forward, 4 aft.
21 tons of the miscellaneous tonnage are for 14 reload torpedoes.