WesWorld

A possible small submarine for the USN to supplement the new Porpoise-class boats currently being built.

Blackfish, US Submarine laid down 1937

Displacement:
542 t light; 556 t standard; 612 t normal; 658 t full load

Dimensions: Length overall / water x beam x draught
180.00 ft / 180.00 ft x 21.00 ft x 14.00 ft (normal load)
54.86 m / 54.86 m x 6.40 m x 4.27 m

Armament:
1 - 3.00" / 76.2 mm guns in single mounts, 13.50lbs / 6.12kg shells, 1937 Model
Quick firing gun in deck mount
on centreline forward
2 - 1.10" / 27.9 mm guns (1x2 guns), 0.67lbs / 0.30kg shells, 1932 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, 1930 Model
Machine guns in deck mounts
on centreline, all amidships
Weight of broadside 15 lbs / 7 kg
Shells per gun, main battery: 150
6 - 21.0" / 533.4 mm submerged torpedo tubes

Armour:

- Conning tower: 1.00" / 25 mm

Machinery:
Diesel Internal combustion generators plus batteries,
Electric motors, 2 shafts, 2,415 shp / 1,802 Kw = 18.00 kts
Range 6,000nm at 10.00 kts
Bunker at max displacement = 102 tons

Complement:
61 - 80

Cost:
£0.163 million / $0.653 million

Distribution of weights at normal displacement:
Armament: 2 tons, 0.3 %
Armour: 2 tons, 0.3 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 0 tons, 0.0 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 2 tons, 0.3 %
Machinery: 67 tons, 10.9 %
Hull, fittings & equipment: 350 tons, 57.1 %
Fuel, ammunition & stores: 70 tons, 11.5 %
Miscellaneous weights: 122 tons, 19.9 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
94 lbs / 43 Kg = 7.0 x 3.0 " / 76 mm shells or 0.1 torpedoes
Stability (Unstable if below 1.00): 1.02
Metacentric height 0.5 ft / 0.2 m
Roll period: 12.5 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: 0.405
Length to Beam Ratio: 8.57 : 1
'Natural speed' for length: 13.42 kts
Power going to wave formation at top speed: 53 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 0.00 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): 181.6 %
- Above water (accommodation/working, high = better): 0.0 %
Waterplane Area: 2,334 Square feet or 217 Square metres
Displacement factor (Displacement / loading): 225 %
Structure weight / hull surface area: 96 lbs/sq ft or 469 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 3.19
- Longitudinal: 2.94
- Overall: 3.00
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

4 torpedo tubes are mounted forward, 2 aft.

12 reload torpedoes are carried, 8 forward and 4 aft.

Quoted

Originally posted by Hrolf Hakonson
4 torpedo tubes are mounted forward, 2 aft.

12 reload torpedoes are carried, 8 forward and aft.

8+8=16. 8 forward and 4 aft, I presume?

Given your industrial power, I'd think sticking with the larger more capable boats gives you more options, and I don't think there's any rush to get hulls in the water at the moment.

Thought I'd fixed that, but yes, 8 forward and 4 aft.

The US submarine force is seriously in need of upgrading, so there's some interest in smaller vessels for the Caribbean (where smaller, handier boats might be advantageous as well).