WesWorld

I'm less confident in my submarine design skills than elsewhere: does this seem like a reasonable coastal defence submarine?


I-2, laid down 1924

Length, 170 ft x Beam, 18.0 ft x Depth, 12.0 ft
525 tons normal displacement (463 tons standard)

Main battery: 1 x 4.1-inch
Secondary battery: 1 x 0.6-inch

Weight of broadside: 35 lbs

6 TT, 19.7" (submerged)

Hull unarmored

Maximum speed for 1498 shp = 16.19 knots
Approximate cruising radius, 4000 nm / 12 kts

Typical complement: 55-71

Operational diving depth: 270 feet
Emergency diving depth: 432 feet
Crush depth: 675 feet



Estimated cost, $325,000 (£81,000)

Remarks:

Caution: lacks seaworthiness -- very limited seakeeping ability.

Caution: Magazines and engineering spaces are very cramped,
and lack adequate watertight subdivision.

Caution: Very cramped ship with excessively poor habitability;
lacks suitable working space.

Ship has quick, 'lively' roll; not a steady gun platform.


Distribution of weights:
Percent
normal
displacement:

Armament ......................... 4 tons = 1 pct
Machinery ........................ 49 tons = 9 pct
Hull and fittings; equipment ..... 306 tons = 58 pct
Fuel, ammunition, stores ......... 75 tons = 14 pct
Miscellaneous weights ............ 90 tons = 17 pct
-----
525 tons = 100 pct

Estimated metacentric height, 0.4 ft

Displacement summary:

Light ship: 450 tons
Standard displacement: 463 tons
Normal service: 525 tons
Full load: 572 tons

Loading submergence 55 tons/foot

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Estimated overall survivability and seakeeping ability:

Relative margin of stability: 1.08

Shellfire needed to sink: 49 lbs = 1.4 x 4.1-inch shells
(Approximates weight of penetrating
shell hits needed to sink ship,
not counting critical hits)

Torpedoes needed to sink: 0.0
(Approximates number of 'typical'
torpedo hits needed to sink ship)

Relative steadiness as gun platform, 1 percent
(50 percent is 'average')

Relative rocking effect from firing to beam, 0.00

Relative quality as a seaboat: 0.00

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Hull form characteristics:

Block coefficient: 0.50
Sharpness coefficient: 0.34
Hull speed coefficient 'M' = 6.44
'Natural speed' for length = 13.0 knots
Power going to wave formation
at top speed: 52 percent


Estimated hull characteristics and strength:

Relative underwater volume absorbed by
magazines and engineering spaces: 237 percent

Relative accommodation and working space: 1 percent


Displacement factor: 235 percent
(Displacement relative to loading factors)


Relative cross-sectional hull strength: 3.66
(Structure weight per square
foot of hull surface: 99 lbs)

Relative longitudinal hull strength: 2.44
(for 0.1 ft average freeboard;
freeboard adjustment -8.3 ft)

Relative composite hull strength: 2.70

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[Machine-readable parameters: Spring Style v. 1.2.1]

170.00 x 18.00 x 12.00; 0.10 -- Dimensions
0.50 -- Block coefficient
1924 -- Year laid down
16.19 / 4000 / 12.00; Oil-fired turbine or equivalent -- Speed / radius / cruise
90 tons -- Miscellaneous weights
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1 x 4.10; 0 -- Main battery; turrets
Central positioning of guns
:
1 x 0.60; 0 -- Secondary battery; turrets
:
0 -- No tertiary (QF/AA) battery
0 -- No fourth (light) battery
6 / 6 / 19.70 -- TT / submerged / size
++++++++++
0.00 -- No belt armor
0.00 / 0.00 -- Deck / CT
0.00 -- No battery armor


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