WesWorld

Quoted

Launched in July 1953 or thereabouts, done with trials early in 1954. Quite an act of faith...

Well, the launch should still be in the 1940s I think... and yes, this design shows my opinion as to what to do when we get to 1950.

Go home, Japan. You're drunk.

You could use 21" guns instead... you know you have them available.

Quoted

Originally posted by Rooijen10

Quoted

Launched in July 1953 or thereabouts, done with trials early in 1954. Quite an act of faith...

Well, the launch should still be in the 1940s I think... and yes, this design shows my opinion as to what to do when we get to 1950.

I stand corrected; completed in July 1953. Just in time to make a last stand at Dien Bien Phu.

Quoted

Go home, Japan. You're drunk.

A case of too much sake...

Quoted

You could use 21" guns instead... you know you have them available.

You have the torpedo guns. My plans utilized the 51cm guns. Now I could have used the 51cm gun version jsut like I could have used the 51cm gun version for the second pair of the Yamato class. I just prefer the 4x3 layout over the 4x2.

Quoted

I stand corrected; completed in July 1953. Just in time to make a last stand at Dien Bien Phu.

... unless I start shifting tons again. Then it might be 1955 or so before it is ready...

Built with the knowledge gained from the I-300 class experimental submarines. The I-305 class is the first submarine class of the Imperial Japanese Navy to use diesel-electric propulsion instead of the direct diesel and electric propulsion.

(I actually prefer the use of the upper belt for the ballast like I did with the I-300, because that makes it seem more part of the submarine instead of floating somewhere above it, but for this I used the traditional way of miscellaneous weights)

I-305, Japan Submarine laid down 1944

Displacement:
2,671 t light; 2,738 t standard; 3,328 t normal; 3,800 t full load

Dimensions: Length overall / water x beam x draught
280.00 ft / 280.00 ft x 26.00 ft (Bulges 32.00 ft) x 26.00 ft (normal load)
85.34 m / 85.34 m x 7.92 m (Bulges 9.75 m) x 7.92 m

Armament:
2 - 0.98" / 25.0 mm guns in single mounts, 0.57lbs / 0.26kg shells, 1944 Model
Anti-aircraft guns in deck mounts
on centreline ends, evenly spread
Weight of broadside 1 lbs / 1 kg
Shells per gun, main battery: 1,500
8 - 21.0" / 533.4 mm submerged torpedo tubes

Armour: (SEE BELOW)
- Belts: Width (max) Length (avg) Height (avg)
Main: 2.11" / 54 mm 15.00 ft / 4.57 m 15.00 ft / 4.57 m
Ends: 8.20" / 208 mm 10.00 ft / 3.05 m 10.00 ft / 3.05 m
255.00 ft / 77.72 m Unarmoured ends
Main Belt covers 8% of normal length
Main belt does not fully cover magazines and engineering spaces

- Torpedo Bulkhead and Bulges:
1.20" / 30 mm 215.00 ft / 65.53 m 40.85 ft / 12.45 m

- Armour deck: 0.56" / 14 mm

Machinery:
Diesel Internal combustion generators plus batteries,
Electric motors, 2 shafts, 7,508 shp / 5,601 Kw = 19.00 kts
Range 25,000nm at 10.00 kts
Bunker at max displacement = 1,062 tons

Complement:
218 - 284

Cost:
£0.810 million / $3.240 million

Distribution of weights at normal displacement:
Armament: 0 tons, 0.0%
Armour: 518 tons, 15.6%
- Belts: 78 tons, 2.3%
- Torpedo bulkhead: 390 tons, 11.7%
- Armament: 0 tons, 0.0%
- Armour Deck: 50 tons, 1.5%
- Conning Tower: 0 tons, 0.0%
Machinery: 192 tons, 5.8%
Hull, fittings & equipment: 1,391 tons, 41.8%
Fuel, ammunition & stores: 657 tons, 19.7%
Miscellaneous weights: 570 tons, 17.1%

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
2,687 lbs / 1,219 Kg = 5,636.4 x 1.0 " / 25 mm shells or 1.3 torpedoes
Stability (Unstable if below 1.00): 1.00
Metacentric height 0.7 ft / 0.2 m
Roll period: 16.4 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: 0.500
Length to Beam Ratio: 8.75 : 1
'Natural speed' for length: 16.73 kts
Power going to wave formation at top speed: 49 %
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): 268.9%
- Above water (accommodation/working, high = better): 0.0%
Waterplane Area: 4,850 Square feet or 451 Square metres
Displacement factor (Displacement / loading): 226%
Structure weight / hull surface area: 144 lbs/sq ft or 701 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 2.92
- Longitudinal: 2.98
- Overall: 2.93
Hull space for machinery, storage, compartmentation is extremely poor
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


Main belt used to sim 24 Type 3 torpedoes (48 tons).
Ends belt used to sim hydraulic torpedo reloading system (30 tons).
560 tons miscellaneous weight for ballast.
10 tons miscellaneous weights for Ninjatousaya System.
Deck armor used to sim sonar, hydrophones and radar (50 tons).
TBH used to sim stronger pressure hull (30mm), allowing the submarine to dive deeper.
Increased Battery capacity: 413 tons for extra cells, simmed as part of the bunker.
Actual Bunker at max displacement = 649 tons.
Actual crew: 109-142.

I thought "Bigger is better" was the USA's motto. Looks like those masters of miniature have mastered the art of massive!

"Bigger is better" but "Everything's bigger in Texas" so it surprises me that the Texans aren't pushing the US government to build bigger ships. Still you need a bigger ship when the Admiral wants all that stuff in her quarters.

Regarding the I-305 diving abilities. I have been playing around with the data of the Type VIIC submarine and of the Type VIIC/42, the latter having a stronger pressure hull. With that data, I altered the Diving, Emergency and Crush Depth modifiers to 1.17x, 2x and 3.4x respectively and multiplied that with 375 (the design's hull strength without TBH) so you would get:

Diving depth: 439 feet
Emergency Depth: 750 feet
Crush Depth: 1275 feet

While the figures of the design without the TBH would be:

Diving depth: 375 feet
Emergency Depth: 600 feet
Crush Depth: 938feet

Is it correct? I don't know. It is merely an experimental idea to apply in SS just like the use of the upper belt to sim the ballast tank on the I-300 in order to get a more realistic beam:depth ratio for a submarine without SS whining about stability being too low (actually it is the same ratio as on the historical I-201). The I-300 is not just an IC experimental submarine but also an OOC one.

A few things to keep in mind is that the Type VIIC/42 is a few hundred tons bigger than the Type VIIC and it is indicated that the pressure hull thickness of the Type VIIC/42 was up to 28mm (compared to what thickness on the Type VIIC I do not know). Torpedo Bulkhead height is half the diameter of the pressure hull and for the length I again looked at the Type VII whose pressurized hull was about 70-75% of the total length of the submarine so I used 75%. Still the Type VIIC and the Type VIIC/42 are more or less the same and I do not know if there are other submarines to use as comparison.

Like I said, it is merely an experimental idea.

Minor tweaks to the carrier and the battleship sims. Navweaps indicated of the 12cm AA rockets that the "mountings were adapted from the 25 mm AA triple gun mounting" so I simmed additional 25mm mounts to reflect this. I also simmed the rockets by using the torpedo entry and used the number of mounts as planned for the Shinano. While messing around with another design, I thought I should do it this way...
... or maybe it was a bad idea to try it :-) .

Edit: minor correction to the miscellaneous breakdown of the two ships.

Nurikabe, Japan Carrier laid down 1944

Displacement:
52,000 t light; 54,295 t standard; 59,042 t normal; 62,840 t full load

Dimensions: Length overall / water x beam x draught
937.09 ft / 910.00 ft x 112.00 ft x 35.00 ft (normal load)
285.63 m / 277.37 m x 34.14 m x 10.67 m

Armament:
8 - 5.00" / 127 mm guns (4x2 guns), 55.12lbs / 25.00kg shells, 1944 Model
Automatic rapid fire guns in deck mounts with hoists
on side, all amidships, 2 raised mounts - superfiring
16 - 2.95" / 75.0 mm guns (8x2 guns), 12.00lbs / 5.44kg shells, 1944 Model
Automatic rapid fire guns in deck mounts with hoists
on side ends, evenly spread
72 - 1.57" / 40.0 mm guns (12x6 guns), 2.00lbs / 0.91kg shells, 1944 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
64 - 0.98" / 25.0 mm guns (16x4 guns), 0.57lbs / 0.26kg shells, 1944 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
48 - 0.98" / 25.0 mm guns (12x4 guns), 0.00lbs / 0.00kg shells, 1944 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 813 lbs / 369 kg
Shells per gun, main battery: 1,990
336 - 4.7" / 120 mm above water torpedoes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 6.00" / 152 mm 600.00 ft / 182.88 m 14.00 ft / 4.27 m
Ends: Unarmoured
Main Belt covers 101% of normal length

- Torpedo Bulkhead:
3.00" / 76 mm 600.00 ft / 182.88 m 33.00 ft / 10.06 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 3.00" / 76 mm 1.00" / 25 mm 2.00" / 51 mm
2nd: 1.00" / 25 mm - 1.00" / 25 mm
3rd: 1.00" / 25 mm - -
4th: 1.00" / 25 mm - -
5th: 0.50" / 13 mm - -

- Armour deck: 4.00" / 102 mm, Conning tower: 2.75" / 70 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 156,514 shp / 116,759 Kw = 30.00 kts
Range 10,000nm at 18.00 kts
Bunker at max displacement = 8,546 tons

Complement:
1,893 - 2,461

Cost:
£16.743 million / $66.974 million

Distribution of weights at normal displacement:
Armament: 130 tons, 0.2%
Armour: 10,154 tons, 17.2%
- Belts: 2,142 tons, 3.6%
- Torpedo bulkhead: 2,198 tons, 3.7%
- Armament: 89 tons, 0.2%
- Armour Deck: 5,636 tons, 9.5%
- Conning Tower: 90 tons, 0.2%
Machinery: 3,997 tons, 6.8%
Hull, fittings & equipment: 15,219 tons, 25.8%
Fuel, ammunition & stores: 7,042 tons, 11.9%
Miscellaneous weights: 22,500 tons, 38.1%

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
87,525 lbs / 39,701 Kg = 1,400.4 x 5.0 " / 127 mm shells or 13.9 torpedoes
Stability (Unstable if below 1.00): 1.08
Metacentric height 6.8 ft / 2.1 m
Roll period: 18.0 seconds
Steadiness - As gun platform (Average = 50 %): 61 %
- Recoil effect (Restricted arc if above 1.00): 0.02
Seaboat quality (Average = 1.00): 1.56

Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.579
Length to Beam Ratio: 8.13 : 1
'Natural speed' for length: 34.69 kts
Power going to wave formation at top speed: 47 %
Trim (Max stability = 0, Max steadiness = 100): 39
Bow angle (Positive = bow angles forward): 30.00 degrees
Stern overhang: 4.00 ft / 1.22 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 40.00 ft / 12.19 m
- Forecastle (15%): 25.60 ft / 7.80 m
- Mid (55%): 25.60 ft / 7.80 m
- Quarterdeck (15%): 25.60 ft / 7.80 m
- Stern: 25.60 ft / 7.80 m
- Average freeboard: 26.46 ft / 8.07 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 82.5%
- Above water (accommodation/working, high = better): 173.6%
Waterplane Area: 76,165 Square feet or 7,076 Square metres
Displacement factor (Displacement / loading): 142%
Structure weight / hull surface area: 144 lbs/sq ft or 701 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.00
- Longitudinal: 0.99
- Overall: 1.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent
Excellent seaboat, comfortable, can fire her guns in the heaviest weather


12x4 25mm mounts (5th gun) simmed for AA Rocket launcher mount.
12cm Rockets simmed as Torpedoes.

Actual rounds per gun
5" => 500 rpg = 122 tons
75mm => 1500 rpg = 214 tons
40mm => 2000 rpg = 262 tons
25mm => 3000 rpg = 515 tons
Total magazine weight: 1113 tons = 1990 rounds

52000
- 16641tons for 129 planes (129 tons per aircraft)
- 750 tons for 30 spare planes in crates (25 tons per aircraft)
- 1000 tons additional aircraft ordnance
- 500 tons for spare parts (4 tons per operational aircraft)
- 405 tons for repair shop (3 tons per operational aircraft, 1 ton per spare aircraft)
- 60 tons for hydraulic catapults (20 tons per catapult)
- 140 tons for elevators
- 250 tons for flight operations center (2 tons per operational aircraft)
- 125 tons for briefing room (1 ton per operational aircraft)
- 250 tons for flagship facilities
- 100 tons for carrier command center
- 308 tons for fire control and fire control center
- 200 tons for radar systems
- 520 tons for damage control and fire suppression systems (1 ton per 100 tons light displacement)
- 130 tons emergency diesel generators (1 ton per 400 tons light displacement)
- 520 tons for air condition system (1 ton per 100 tons light displacement)
- 188 tons for degaussing coils (1 ton per 5 feet of length (oa))
- 132 for mount improvements
--- 60 tons for 5" mounts
--- 32 tons for 75mm mounts
--- 24 tons for 40mm mounts
--- 16 tons for 25mm mounts
- 75 tons for 12x28 12 cm AA Rocket launchers
- 206 tons for crew comfort.
Total: 22500


Oshima, Japan Battleship laid down 1944

Displacement:
94,000 t light; 101,132 t standard; 108,149 t normal; 113,762 t full load

Dimensions: Length overall / water x beam x draught
1,043.71 ft / 1,020.00 ft x 130.00 ft (Bulges 140.00 ft) x 40.00 ft (normal load)
318.12 m / 310.90 m x 39.62 m (Bulges 42.67 m) x 12.19 m

Armament:
12 - 18.11" / 460 mm guns (4x3 guns), 3,897.77lbs / 1,768.00kg shells, 1944 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, evenly spread, 2 raised mounts - superfiring
40 - 5.00" / 127 mm guns (20x2 guns), 55.12lbs / 25.00kg shells, 1944 Model
Automatic rapid fire guns in deck mounts with hoists
on side, all amidships, all raised mounts - superfiring
40 - 2.95" / 75.0 mm guns (20x2 guns), 12.00lbs / 5.44kg shells, 1944 Model
Automatic rapid fire guns in deck mounts with hoists
on side, evenly spread, 12 raised mounts
72 - 1.57" / 40.0 mm guns (12x6 guns), 2.00lbs / 0.91kg shells, 1944 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, all raised mounts
208 - 0.98" / 25.0 mm guns (52x4 guns), 0.57lbs / 0.26kg shells, 1944 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, 12 raised mounts
Weight of broadside 49,721 lbs / 22,553 kg
Shells per gun, main battery: 177
336 - 4.7" / 120 mm above water torpedoes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 17.9" / 454 mm 600.00 ft / 182.88 m 17.00 ft / 5.18 m
Ends: 14.0" / 356 mm 140.00 ft / 42.67 m 8.00 ft / 2.44 m
280.00 ft / 85.34 m Unarmoured ends
Upper: 2.25" / 57 mm 600.00 ft / 182.88 m 23.00 ft / 7.01 m
Main Belt covers 90% of normal length

- Torpedo Bulkhead and Bulges:
3.00" / 76 mm 600.00 ft / 182.88 m 50.00 ft / 15.24 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 26.0" / 660 mm 15.0" / 381 mm 20.0" / 508 mm
2nd: 3.00" / 76 mm 1.00" / 25 mm 2.00" / 51 mm
3rd: 1.00" / 25 mm 1.00" / 25 mm 1.00" / 25 mm
4th: 1.00" / 25 mm 1.00" / 25 mm -
5th: 1.00" / 25 mm 1.00" / 25 mm -

- Armour deck: 9.00" / 229 mm, Conning tower: 20.00" / 508 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 201,732 shp / 150,492 Kw = 29.00 kts
Range 10,000nm at 18.00 kts
Bunker at max displacement = 12,630 tons

Complement:
2,981 - 3,876

Cost:
£54.883 million / $219.533 million

Distribution of weights at normal displacement:
Armament: 4,937 tons, 4.6%
Armour: 41,097 tons, 38.0%
- Belts: 9,917 tons, 9.2%
- Torpedo bulkhead: 3,330 tons, 3.1%
- Armament: 9,016 tons, 8.3%
- Armour Deck: 17,855 tons, 16.5%
- Conning Tower: 978 tons, 0.9%
Machinery: 5,151 tons, 4.8%
Hull, fittings & equipment: 38,814 tons, 35.9%
Fuel, ammunition & stores: 14,149 tons, 13.1%
Miscellaneous weights: 4,000 tons, 3.7%

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
171,363 lbs / 77,729 Kg = 57.7 x 18.1 " / 460 mm shells or 34.4 torpedoes
Stability (Unstable if below 1.00): 1.11
Metacentric height 9.1 ft / 2.8 m
Roll period: 19.5 seconds
Steadiness - As gun platform (Average = 50 %): 60 %
- Recoil effect (Restricted arc if above 1.00): 0.68
Seaboat quality (Average = 1.00): 1.22

Hull form characteristics:
Hull has low quarterdeck
and transom stern
Block coefficient: 0.663
Length to Beam Ratio: 7.29 : 1
'Natural speed' for length: 36.75 kts
Power going to wave formation at top speed: 46 %
Trim (Max stability = 0, Max steadiness = 100): 49
Bow angle (Positive = bow angles forward): 35.00 degrees
Stern overhang: 2.00 ft / 0.61 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 31.00 ft / 9.45 m
- Forecastle (31%): 21.20 ft / 6.46 m
- Mid (43%): 26.10 ft / 7.96 m
- Quarterdeck (7%): 19.20 ft / 5.85 m (26.10 ft / 7.96 m before break)
- Stern: 19.20 ft / 5.85 m
- Average freeboard: 25.02 ft / 7.63 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 67.6%
- Above water (accommodation/working, high = better): 160.1%
Waterplane Area: 107,238 Square feet or 9,963 Square metres
Displacement factor (Displacement / loading): 114%
Structure weight / hull surface area: 270 lbs/sq ft or 1,317 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.00
- Longitudinal: 1.00
- Overall: 1.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent
Good seaboat, rides out heavy weather easily

Actual main gun shell average weight 1775 kg

Actual 25mm mounts: 40x4 (= 160 guns)
12x4 25mm mounts simmed for AA Rocket launcher mount.
12cm Rockets simmed as Torpedoes.

Actual shells per gun
46cm = 120 rounds per gun (3131 tons total)
5" = 500 rounds per gun (735 tons total)
75mm = 1500 rounds per gun (535 tons total)
40mm = 2000 rounds per gun ( 131 tons total)
25mm = 3000 rounds per gun (306 tons total)

94000
- 80 tons for helicopter landing pad.
- 50 tons for 2 helicopters.
- 400 tons for flagship facilities
- 350 tons for fire control and fire control center
- 200 tons for radar systems
- 940 tons for damage control and fire suppression systems
- 235 tons emergency diesel generators
- 940 tons for air condition system
- 209 tons for degaussing coils
- 75 tons for 12x28 12 cm AA Rocket launchers
- 444 for mount improvements
--- 300 tons for 5" mounts
--- 80 tons for 75mm mounts
--- 24 tons for 40mm mounts
--- 40tons for 25mm mounts
- 77 tons for crew comfort.
Total: 4000 tons

Thought I would give Subsim a try for a more proper submarine hull depth/beam ratio without having to either use something else than miscellaneous weights to sim the ballast tank or have stability of the sim drop well below 1.00 as I would have to do with SS (like I did with the I-300 design)...

One thing I'm not sure about. Considering that this sub, like its predecessor, has diesel-electric propulsion, should the 'ElecHP' not be that what determines the maximum surface speed? After all, the electric engines are the ones that drive the shafts, not the diesel engines. The sub won't move an inch if it only had the diesel engines even if they could produce 1,000,000 hp. Or am I just saying something stupid here?



I-310 class Submarine
Date: 1945
Type: Oceanic
Length: 95.0m
Beam: 10.2m
Draft: 10.6m
Crew: 123
Crush depth: 317.5m (baseline)
Light Displacement 3843t
Loaded Displacement 4643t
Full Displacement 5136t
wt fuel&batts: 1250t
Reserve buoyancy: 10%

Armament:
- 8 x 21" (bow)
- 2x1 25mm AA guns (used misc weights)
ElecHP: 15000hp
DieselHP: 7500hp
Speed:
- Max Surf Speed: 15.0 knots
- Max Sub Speed: 19.2 knots
Range:
- Surfaced: 18128nm@10 knots
- Submerged: 270nm@5 knots
Tons Oil: 800t
Tons Battery: 450t

Miscellaneous Weight: 1000 tons
- 48 tons for 24 Type 3 torpedoes.
- 4 ton for 2 25mm AA guns on retractable mounts.
- 1 ton for 3150 rounds of 25mm ammunition.
- 30 tons for hydraulic torpedo reloading system.
- 10 tons for Ninjatousaya System.
- 50 tons for sonar, hydrophones and radar
- 560 tons for stronger pressure hull (+30mm), allowing the submarine to dive deeper.
- 145 tons for highly streamlined form of pressure hull and casing.
- 40 tons for steel plate deck.
- 8 tons for large horizontal control surfaces at the stern.
- 12 tons for silent running motors (450hp, max speed 6 knots).
- 39 tons for climate control.
- 39 tons for damage control and fire suppression systems.
- 10 tons for emergency generators.
- 4 tons for freezer.

Depths

Baseline
Diving Depth: 127m
Emergency Depth: 203m
Crush Depth: 317.5m

Enhanced pressure hull (using the ratios I got with the I-305)
Diving Depth: 148.5m
Emergency Depth: 254m
Crush Depth: 431.8m

Quoted from "Rooijen10"

diesel-electric propulsion, should the 'ElecHP' not be that what determines the maximum surface speed?

As far as I know, its hardcoded into the spreadsheet that Diesels relate to surface speed and Electric relates to underwater speed.

Consider "ElecHP" to refer to the batteries, not the electric generators that turn the shafts. On the surface, the diesel engines run the generator that makes the electricity that turns the shafts, while submerged the batteries run that generator instead. You can use the batteries on the surface, but in 98% of all circumstances you'll be using the diesels on the surface.

Quoted

- 560 tons for stronger pressure hull (+30mm), allowing the submarine to dive deeper.
- 145 tons for highly streamlined form of pressure hull and casing.

...I am not convinced about these two items. Can you make a case?

Quoted

You can use the batteries on the surface, but in 98% of all circumstances you'll be using the diesels on the surface.

True. I was thinking about that as well. Even if the running time is quite limited due to the capacity of the batteries, a sub like this would run faster on the surface using the batteries than it would running on diesel power. It is not something you want to do though, but it seems to me to be proper to indicate with the max surface speed that the sub is capable of running at speeds in excess of what Subsim gives for short periods of time (for the I-310, I estimate 8-10 minutes at 18.9 knots based on what Subsim gives me).

Quoted

...I am not convinced about these two items. Can you make a case?

Considering that you do not indicate exactly what aspect you are not convinced in, I doubt anyone would be able to do that.

... so I will just throw as much at you regarding that as I can in the hope that there is something useful in there...


The stronger pressure hull is something I incorporated in the previous I-305 design (a few post above the design I posted), although since that is an SS sim I used the Torpedo Bulkhead Armor to sim the stronger pressure hull with SS. While it is not mentioned, one of the I-300 class experimental subs would have this as well.

On wiki, it says that the I-201 has a hull that is 79 meters long and the pressure hull is 59.2 meters long. So about 75% of the I-201's length is pressurized. I used the same percentage as base for the previous design and this design as well in SS to give a rough estimate as to how long the pressurized part of the hull would be.

With the I-305, the sub is 280 feet long. 75% is 210 feet. As it is slightly longer than the I-201, I went for a length of 215 feet instead. With the I-310, the sub is 95 meters long (310ft/94.49m in my SS sim). 75% is 232.5 feet which I 'rounded up' to 250 feet due to the fact that the I-310 is about 15 meters longer than the I-201. Should be noted that in both cases those lengths are guesses.

I need a height for the belt. The Pressure hull is round so some simple math using 'Pi' and either multiply it by the diameter or 2*radius.

On the I-305, you get 26ft * 'Pi' = 81.68 feet for the perimeter. Considering that you have 2 Torpedo bulkheads (one on each side), dividing the 81.68 feet by 2 for two halves gives you 40.84 feet and I simmed it as being 40.85 feet high.

Using the above for the I-310, you will get 10.2m * 'Pi' = 32.04m (something I did wrong as I used 32 ft (= 9.75m) for the SS sim and when I went to Subsim, I used 10.2m). So the height of the Torpedo Bulkhead should be 16.02 meters (= 52.57 ft and I used 50.3 ft in the SS sim to figure out the weight needed).

The thickness is based on what wiki says about the Type VIIC/42 ("It would have had a much stronger pressure hull, with skin thickness up to 28 mm") and which is also the bit that inspired me to apply a thicker pressure hull on the submarine designs. Now rather than figuring out (read: guessing) what the average thickness would be of the pressure hull, for simplicity I assumed that it is 28mm thick overall and actually simmed it as 1.2"/30mm thick and ignore that fact that this would be added to whatever thickness SS assumes the pressure hull to be rather than it being the actual thickness of the pressure hull.

Now entering all the above figures, you will get for the I-305 a cylinder representing the pressurized section of the submarine that is 215ft long, 40.85ft high and 1.2" thick and SS gives 390 tons for that. With the I-310, you will get 250ft by 52.57ft that is 1.2" thick which gives a weight of 584 tons while I simmed it at 560 tons (should be okay as I had a leftover of 25 tons which I randomly added to the streamlining).

Streamlining... no idea. That is just me guessing there. Should be noted that the steel plate deck bit is (IIRC) also part of the streamlining so I will mention it here as well. It is based on what is said in the I-201 wiki entry ("Give the pressure hull and casing a highly streamlined form" and "Use steel plates for the upper deck rather than wood").

For the metal plates on the deck, I took the simple route by using the deck armor. No idea how thick the steel plates would be so I went for 8mm thick which according to SS would be 39 tons.

For the streamlining of the hull, I went the same way as with the pressurized hull by creating a cylinder that would represent the submarine (so 95m long and diameter of 10.2m; I used 10.2m instead of 10.6m due to the ends of the sub being narrower than the middle part). For this I went with 5mm thick plates which gives me a value of 119 tons. Subtracting the 24 tons still needed for the presurized hull, I would still have 121 tons left.

Is it correct?
Your guess is as good as mine. Ignoring the fact that this all adds to whatever already exists on the submarine, I am not sure if it is correct to use armor plating to sim ordinary steel plates, but I guess this is better than adding nothing at all and stating as a fact that the sub can dive deeper and is streamlined.

Is it possible?
Considering that it was used/planned to be used in historical subs, I would think so yes. In one sub? Don't know, but that is why it is a fairly big design instead of something the size of the I-201 or the Type VII. Seems more logical and proper that it would fit in that rather than in a small sub design. I doubt there are many sub designs out there that are bigger than this one.

Does it work?
Wiki doesn't say anything about how effective the streamlining on the I-201 was, but considering its underwater speed, it probably helped somewhat. As for the pressure hull, all the Type VIIC/42 were cancelled so it is just speculation whether or not it could actually dive twice as deep as the previous VIICs, but a sub with a thicker pressure hull should be able to dive deeper than a sub with a thinner pressure hull (assuming the same structure/materials are used). While I did add an altered list of depths for the thicker pressure hull which is based on what I did for the I-305, I did not alter the speed of the design as I have no idea what effect the streamlining has on the speed so I left it like that (or the possible effects the horizontal control surfaces at the stern will have).

Is it needed?
I consider it as much needed as 8 inch automatics or ASW Helicopters or ASW rockets or AA Rockets... so no, not really... but it does make it different from other designs and it is a continuation of the previous design.


Still in the end you have to remember that all that stuff is based on what I found on wiki... and we all know how reliable wiki can be.

Hmmm... looking back at that depth calculation post, I apparently based the length of the pressure hull based on the numbers given on the Type VII page (70-75%) and not on the I-201 (although the I-201's 75% is along the same lines as the Type VII)...

... and I am not sure what I was drinking back in September when I typed the "Torpedo Bulkhead height is half the diameter of the pressure hull" bit. So according to me back then, 26/2= 40.85 ft... no wonder I screwed up my math exams back in '91... *bangs head on desk*

That's about when I gave up on math, too.

To clarify my feelings of unease...

I think Subsim automatically accounts for better engine hp/ton and increased streamlining when you enter the year the design is laid down, hence the huge rise in underwater speed and range moving from a 1940 to a 1945 design. To then use miscellaneous weight to claim that you're adding that same streamlining... strikes me as a bit shady.

Similarly, I'm looking at the "improved" crush depths and I think they're unnaturally high, particularly for this era. (I feel the numbers offered by Subsim were already unrealistically generous.) For comparison, most WWII submarines (Balao and Tench as an example) had test depths of 120m or thereabouts, and are specifically called out as having particularly high-strength hulls in order to dive deep. Yet here's a design with twice that diving depth.

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I think Subsim automatically accounts for better engine hp/ton and increased streamlining when you enter the year the design is laid down, hence the huge rise in underwater speed and range moving from a 1940 to a 1945 design. To then use miscellaneous weight to claim that you're adding that same streamlining... strikes me as a bit shady.

Okay, I did not know that. I thought that a feature like that would have to be added to the miscellaneous weights in order to justify its existence on the submarine which I did, but if it is already assumed by Subsim to be part of the sim, then adding the same streamlining would actually do nothing.

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Similarly, I'm looking at the "improved" crush depths and I think they're unnaturally high, particularly for this era. (I feel the numbers offered by Subsim were already unrealistically generous.) For comparison, most WWII submarines (Balao and Tench as an example) had test depths of 120m or thereabouts, and are specifically called out as having particularly high-strength hulls in order to dive deep. Yet here's a design with twice that diving depth.

I got the impression with messing around with Subsim, the sub's Crush depth does not change if you add or remove stuff from your sub, unlike with SS where the depths are determined by the overall hull strength which constantly changes when you add or remove stuff from your sub. While I haven't really looked into it, I also got the impression that the bigger the sub you sim with Subsim, the deeper it can dive. (I think I will have to play some more with it to see what it all does) edit: no it doesn't... greater sub =/= deeper diving depth.

I'm not sure how to read "test depth". What determines "test depth"? To me it sounds more like a depth you dive to do various test you sub and is not really related to the "Diving Depth", "Emergency Depth" or "Crush Depth" values we calculate using the formulas in the Springstyle notes and more of an 'in between' depth. While looking around I also ran across a page that mentioned a sub diving below "design depth" which seems to be deeper than "test depth" but not "crush depth" and on another page on the Gato, it more or less seems to treat the 90m depth of the Gato and the 120m of the Tench as being the same as our "Diving Depth" (I probably should stop now as it is making me more and more confused as to what it is ).

For the I-300 sim I actually have the depths as Diving depth (OHSx1x100), Test Depth (OHSx1.25x100), Emergency Depth (OHSx1.6x100) and Crush Depth (OHSx2.5x100). With that sim's OHS and multiplying that with 1.25 and 100, I got a test depth of 357.5 feet which is close to the 360ft test depth given for the I-201 on wiki. It's probably not quite right because with that I am combining SS data with data from wiki.

To me, the crush depth estimates given on the Type VII wiki page are more useful than "test depth" values because, eventhough they are estimates, there is little doubt about which SS depth value you have to compate it with. On wiki, the crush depth of the Type VIIC/42 is given as 350-400m which is not too far of the 431.8m I have calculated. I find it interesting that the page wiki refers so gives the Type VIIC/42 crush depth as 656ft (200m), but in the text above about the same sub, it says "With the planned increase in thickness to 1.1in (28mm), the crush depth of this boat would have been an astonishing 1,640ft (500m)."


Despite that, what you said about the depths being unnaturally high is still true if you compare it with the existing subs. The submarine class that inspired me to add the thicker hull was never build (as I mentioned above).



Now for something else... when I look at the cross section of the hull of the Typhoon submarine, it looks pretty flat to me. Are there submarines that are flatter than the Typhoon class submarines?

The Typhoon is that fat and flat because it's an outer hull wrapped around two cylindrical pressure hulls (with a third under the sail). The Oscars have pretty squared off hulls, but that's because of the side-saddle missile tubes. I can't think of any other subs that remotely approach that form-factor. The next closest thing would be the missile hump-backs on earlier SSBNs

From DK Brown's 'Nelson to Vanguard'

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Operational Depth: This was the maximum depth which could be used safely in operations. It included margins for error in the design calculation or in building and for an inadvertent overshoot in manoeuvring etc.

Test Depth: A new submarine would carry out a test dive, usually to operational depth. Many captains would go 10 per cent deeper to give confidence to their crew [Footnote: Since this habit was well known the 10 per cent was added to the factor of safety in setting operational depth]

Collapse Depth: The depth calculated by the designer at which the pressure hull would collapse under water pressure. It seems that by about 1930 it was British practice (and that of most navies) to take the operational depth as half the collapse depth. Note that in Oberon 'diving depth' was quoted as 500ft, operational depth as 300ft and test depth as 200ft. It is probable that 500ft was the expected collapse depth.

So on this basis, test depth is nothing more than operational depth as the additional 10% safety is already factored into operational depth.

As to crush depth, Brown includes a table of British submarines and their 'formula' depth compared to their actual operational and deepest recorded dives, its worth recording that most RN subs never actually achieved their 'formula' collapse depth, especially the earlier submarines in the 1920s and 1930s. Only the wartime 'S' and the 1945 'A' exceeded their collapse depth in post-war trials (1940 'S' formula 534ft, max 540ft, trials 527-537ft; 1942 'S' formula 700ft, trial 647ft; 'A' formula 840ft, trial 877ft).

Thanks for that info, Hood...


Looking at those descriptions, I guess it should be okay to keep the I-300's test depth bit the way I use it as long as it is clear how it is calculated (since I used 25% instead of 10%).

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The Typhoon is that fat and flat because it's an outer hull wrapped around two cylindrical pressure hulls (with a third under the sail). The Oscars have pretty squared off hulls, but that's because of the side-saddle missile tubes. I can't think of any other subs that remotely approach that form-factor.

Okay, so using those two, you have depth:beam ratios of 0.763 for the Oscar I, 0.789 for the Oscar II and 0.744 for the Typhoon... and which are nowhere near the 0.667 (depth about 2/3 of beam) that the SS notes claims to be "typical for subs of pre-nuke era" eventhough the two are nuclear era subs. This made me think because when I am thinking of the pre-nuclear era subs, I'm thinking of vessels whose beam and depth create something that looks more round than the Oskar or the Typhoon thus even further removed from the 0.667 ratio than those two nuclear subs. It is something I noted when I was simming the I-300. Using the I-201 wiki data, the beam is about 6 meters and wiki is kind enough to give me the proper value to enter for depth which is 7 meters. That gives me a depth:beam ratio of 1.167.

Looking at the various (line)drawings, I get the next depth:beam ratios:
Type II = 1.284
Type VII = 0.982
Type IX = 0.898
Type XXI = 1.153
Gato = 0.871
Balao = 0.873
Tench = 0.960
I-201 = 1.144
I-400 = 0.85
I-19 = 0.9
S-class (1914) = 0.971
T-class = 0.663

The reason that the T-class is so flat is because of the big ballast tanks on the sides of the pressure hull. But that is just one class of 12 classes I looked at, so I would hardly call it typical. Far from it. Looking at those 12 submarine designs, a 0.85-1.00 ratio seems to be far more typical for subs (8 of 12 classes checked). This is the main reason I am currently looking at Subsim to work with since there is no stupidly located miscellaneous weights around to worry about and that messes too much with the stability and which forces you to sim a flat submarine in order to keep your stability above 1 (this is also the reason that for the I-300 I experimented with using upper belt armor to sim the ballast tanks instead of the miscellaneous weights as it is located lower in the hull).