Parthian Ships 1928 +

The Rock Doctor · April 20, 2024, 05:05:12 PM

The battleship is certainly a solid unit. I like it.

You're absolutely right that my cruiser critique lacked aplomb. I feel the beam is on the narrow side for quads. As for armor...given the mission you're describing - which I take to be sneak in, whack high-value targets, run away - I'd go for the AON design. You should not, in theory, be encountering a significant amount of lighter gunfire in that scenario.

That said, 31 knots may be fast enough if you're fighting Byzantines or NPCs. Might not be if you're eyeballing Japan.

Jefgte · April 20, 2024, 05:14:39 PM

It's time for Parthian super big guns.

Kaiser Kirk · April 20, 2024, 05:58:18 PM

Beam- SS gives no warnings.

The bulged beam is slightly (65.62) greater than USS Witchia (61.75ft) with 3t3 205mm turrets, so that might or might not be a valid concern. Another meter of beam might be reasonable, but then again, I only have 2 turrets, so they can be closer to mid-ship, which should be broader than where "A" is on Wichita. But my guns are Quad 215 not Triple 205... I doubt we have the tools to figure it out, but we can probably say I am close.

Edit : Also, Wichita was 608ft long, so running just about 10:1, so beam may have been driven in part by length and not by minimum needed for the turrets.

Ironically I did proffer a rule for determining minimum beam for a particular turret type, and folks did not want to use that.

Instead, we do have an agreed on rule for this - sufficient beam to mount particular weapons was the cause of the discussion of how to judge, with the resolution of SS being the judge - I'm going to stick to that.

Big Guns :
I was planning on fielding the 435mm quite some time ago, but the 1915 tech 435L43 just lacks the muzzle velocity to be more effective than the 390L46, while weighing more.
So I needed the 1925 tech and the 435L47 to be researched so I can field it.

I have 3 battleships under consideration - that Wirozag at 39,000 tons with it's shabby armor, the Asi at 39000 but 23 knots and better armor, and the Imulhu at 45,000 with 26 knots and the better armor. I'll post the Asi/Imulhu later

First the revised Frawar
An earlier version had a deck break, but the VI posted did not, which meant the upper belt calculations were off - as were deck heights.

I tie Belt heights to deck heights, so that caused a recalculation.
To save weight, I wound up tapering the lower 1m of the main belt , from -1.5m to -2.5m below WL, dropping from 325 to 230.

That allowed the expanded Upper belt, and +5mm on the deck armor.

QuoteFrawar "Bastion" VII, Parthia Battleship laid down 1932

Displacement:
19,000 t light; 20,417 t standard; 21,625 t normal; 22,592 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(459.32 ft / 452.76 ft) x 91.86 ft (Bulges 95.14 ft) x (30.61 / 31.75 ft)
(140.00 m / 138.00 m) x 28.00 m (Bulges 29.00 m) x (9.33 / 9.68 m)

Armament:
8 - 13.11" / 333 mm 43.0 cal guns - 1,311.75lbs / 595.00kg shells, 110 per gun
Breech loading guns in turret on barbette mounts, 1927 Model
2 x 4-gun mounts on centreline ends, evenly spread
16 - 5.12" / 130 mm 47.0 cal guns - 85.98lbs / 39.00kg shells, 320 per gun
Dual purpose guns in deck and hoist mounts, 1930 Model
6 x 2-gun mounts on sides, evenly spread
2 raised mounts
2 x 2-gun mounts on centreline ends, evenly spread
2 raised mounts
24 - 1.46" / 37.0 mm 70.0 cal guns - 1.72lbs / 0.78kg shells, 3,000 per gun
Anti-air guns in deck and hoist mounts, 1930 Model
4 x 2 row quad mounts on side ends, evenly spread
4 raised mounts
2 x 2 row quad mounts on sides, forward deck centre
2 double raised mounts
24 - 0.91" / 23.0 mm 90.0 cal guns - 0.44lbs / 0.20kg shells, 5,000 per gun
Anti-air guns in deck mounts, 1929 Model
12 x Twin mounts on sides, evenly spread
12 double raised mounts
Weight of broadside 11,922 lbs / 5,408 kg

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 12.8" / 325 mm 294.29 ft / 89.70 m 13.78 ft / 4.20 m
Ends: 1.38" / 35 mm 158.43 ft / 48.29 m 12.01 ft / 3.66 m
Upper: 2.95" / 75 mm 294.29 ft / 89.70 m 13.58 ft / 4.14 m
Main Belt covers 100 % of normal length
Main Belt inclined -15.00 degrees (positive = in)

- Torpedo Bulkhead - Additional damage containing bulkheads:
1.50" / 38 mm 294.29 ft / 89.70 m 31.79 ft / 9.69 m
Beam between torpedo bulkheads 62.34 ft / 19.00 m

- Hull Bulges:
0.35" / 9 mm 301.84 ft / 92.00 m 22.41 ft / 6.83 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 12.6" / 320 mm 4.72" / 120 mm 10.2" / 260 mm
2nd: 2.56" / 65 mm 1.57" / 40 mm 1.97" / 50 mm
3rd: 0.31" / 8 mm 0.31" / 8 mm 0.31" / 8 mm
4th: 0.31" / 8 mm - -

- Protected deck - multiple decks:
For and Aft decks: 5.51" / 140 mm
Forecastle: 1.38" / 35 mm Quarter deck: 4.13" / 105 mm

- Conning towers: Forward 10.04" / 255 mm, Aft 2.56" / 65 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 54,769 shp / 40,858 Kw = 24.00 kts
Range 6,726nm at 14.00 kts
Bunker at max displacement = 2,175 tons

Complement:
891 - 1,159

Cost:
£8.172 million / $32.687 million

Distribution of weights at normal displacement:
Armament: 2,153 tons, 10.0 %
- Guns: 2,153 tons, 10.0 %
Armour: 7,820 tons, 36.2 %
- Belts: 2,998 tons, 13.9 %
- Torpedo bulkhead: 518 tons, 2.4 %
- Bulges: 89 tons, 0.4 %
- Armament: 1,230 tons, 5.7 %
- Armour Deck: 2,774 tons, 12.8 %
- Conning Towers: 211 tons, 1.0 %
Machinery: 1,617 tons, 7.5 %
Hull, fittings & equipment: 6,764 tons, 31.3 %
Fuel, ammunition & stores: 2,625 tons, 12.1 %
Miscellaneous weights: 647 tons, 3.0 %
- Hull below water: 157 tons
- Bulge void weights: 130 tons
- Hull above water: 38 tons
- On freeboard deck: 30 tons
- Above deck: 292 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
30,600 lbs / 13,880 Kg = 27.2 x 13.1 " / 333 mm shells or 5.8 torpedoes
Stability (Unstable if below 1.00): 1.13
Metacentric height 5.6 ft / 1.7 m
Roll period: 16.9 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.63
Seaboat quality (Average = 1.00): 1.01

Hull form characteristics:
Hull has a flush deck,
a ram bow and a cruiser stern
Block coefficient (normal/deep): 0.574 / 0.578
Length to Beam Ratio: 4.76 : 1
'Natural speed' for length: 21.28 kts
Power going to wave formation at top speed: 61 %
Trim (Max stability = 0, Max steadiness = 100): 69
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: -6.56 ft / -2.00 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 20.00 %, 23.62 ft / 7.20 m, 21.16 ft / 6.45 m
- Forward deck: 32.50 %, 21.16 ft / 6.45 m, 18.70 ft / 5.70 m
- Aft deck: 32.50 %, 18.70 ft / 5.70 m, 18.70 ft / 5.70 m
- Quarter deck: 15.00 %, 18.70 ft / 5.70 m, 19.69 ft / 6.00 m
- Average freeboard: 19.86 ft / 6.05 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 96.9 %
- Above water (accommodation/working, high = better): 122.6 %
Waterplane Area: 29,688 Square feet or 2,758 Square metres
Displacement factor (Displacement / loading): 106 %
Structure weight / hull surface area: 183 lbs/sq ft or 893 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.88
- Longitudinal: 3.10
- Overall: 1.00
Adequate machinery, storage, compartmentation space
Excellent accommodation and workspace room
Ship has slow, easy roll, a good, steady gun platform

The VII corrects the belt armor based on this versions freeboard and so deck heights.

Still designed as a 'cheap' replacement to the old predreadnaughts capable of supporting the territorial fleets and providing convoy escorts. These could also oppose similar byzantine ships, but would compete in the build order with the Armored cruisers.

The class reverts to a protected deck and armored upper citadel.
The upper armored deck is 35mm, proof against bombs and QF

Armor
35mm bomb deck is above 2 deck space, excluding HE, and detonating AP prior to main deck
Upper Belt covers from freeboard to top of main belt.
Main Belt Covers from +1 m above crown of 105mm protective deck to protect its slopes 2.5m below waterline.
The TDS rises to seal to the bottom of the protective deck, serving as a splinter and explosion barrier.

Upper Belt :

Upper Belt is 4m high.
It is outsloped at 15%
4/cos(15) = 4.1411 = 4.14

Main Belt :
Covers from 1.7m above WL to -2.5m below WL, a total height of 4.2m.
The first 3.2m is full thickness, the last 1m tapers to 230mm.

volume
1040 = 3.2 * 325
277.5 = ((325-230)/2 * 1) + (1*230)
-----
1317.5 volume
divide by 325mm thickness
4.0538m high
It is outsloped at 15%.
4.0538/cos(15) = 4.1968 = 4.20

Waterline protection : 325mm (belt) outsloped backed by the 105mm protective deck and the 38mm TDS = 325+ (105*1.5)/2 + 38/2 = 423

End Belts : These are thickened slopes for protective decks,
so 70mm slopes fore, and 145mm slopes aft.

Decks : The citadel is protected by a 35mm upper deck and 105mm protective deck, for a vertical of 122mm. The upper deck thereby serves as a bomb deck to activate and detonate the shells and bombs short of the main deck.

The slopes of the protective deck are largely protected by the main belt rising above it.

TDS : TDS rises to seal to the bottom of the protective deck at +0.7 above WL

Reserve : 130t

AD
217t - Fire Control 1930
25t - LR Radio
25t - Hulesmeyer
25t - Searchlight Tower (NF)

OD
5t - Paravanes
20t- Scout Plane - on stern
5t - Gunpowder Cat

HAW
19t - Extra Fire Extinguishers
19t - CO2 Compressor AC

HBW
19t - Extra Pumps
138t - Torpedo Nets

Decks
+5.7 Weather deck - 35mm
+3.2 Battery Deck
+1.7 top of main belt, bottom of upper belt
+0.7 Crown of portective deck 100mm, Top TDS
-1.8 bottom of protective deck slope,
-2.5 bottom of main belt
-4.30 1st platform deck
-7.80 Engineering Deck
-8.79 double bottom, bottom of torpedo defenses
-9.33 Keel

Kaiser Kirk · April 20, 2024, 08:28:12 PM

Quote from: The Rock Doctor on April 20, 2024, 05:05:12 PMThe battleship is certainly a solid unit.

The conundrum with the battleship is that I am *close* to finishing decapping plates.
So it is tempting to delay slightly so I can lay down ships with decapping plates.

The Asi / Imulhu started as a series of designs for 1926, looking for a 435mm armed,
23knot battleship that was affordable. The Byzantine line of the time was 21 knots, so I thought I would increase +2 knots over that. The current large BCs building I doubt Parthia knows are BCs, we'd expect something similar to our own ships...we'd expect DNs. We'll figure out they are successors to the Europa soon enough.

I did just extend several docks to 235m long, with ones in Ria and Dumai to support those fleets. So I can build longer than 190m ships now...if needed.
After all, 235 vs 190 is 23% larger target - shells and torpedoes.

So there are several versions.
23 knots - new Homefleet speed- here as Asi

26 knots - Expeditionary fleet speed - was valid choice ~1922, might be a little slow - here as Imulhu.

30 knots - still a 1926 design, 57,600 tons 30knot, 3T3x 435mm. With the growing number of 30knt battlewagons, - the two Byzantine BCs, Empress Amelia, etc. Royal Soveriegn may be friend, but even Parthia can have battlewagon envy...
It was just too big to consider, but if needed so it may get updated and brought forward.

Kaiser Kirk · April 20, 2024, 08:32:19 PM

So this is Asi

QuoteAsi / Ilmulhu, Parthian Battleship laid down 1932

Displacement:
   39,000 t light; 42,105 t standard; 44,841 t normal; 47,030 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (622.66 ft / 616.80 ft) x 114.83 ft (Bulges 124.67 ft) x (31.50 / 32.91 ft)
   (189.79 m / 188.00 m) x 35.00 m (Bulges 38.00 m) x (9.60 / 10.03 m)

Armament:
8 - 17.13" / 435 mm 47.0 cal guns - 2,711.69lbs / 1,230.00kg shells, 140 per gun
     Breech loading guns in turret on barbette mounts, 1930 Model
     2 x 4-gun mounts on centreline, evenly spread
20 - 4.53" / 115 mm 47.0 cal guns - 55.12lbs / 25.00kg shells, 400 per gun
     Dual purpose guns in deck and hoist mounts, 1931 Model
     8 x 2-gun mounts on side ends, evenly spread
      4 raised mounts - superfiring
     2 x 2-gun mounts on centreline ends, evenly spread
      2 double raised mounts
40 - 1.46" / 37.0 mm 70.0 cal guns - 1.72lbs / 0.78kg shells, 6,000 per gun
     Anti-air guns in deck and hoist mounts, 1929 Model
     10 x 2-gun mounts on sides, evenly spread
      8 raised mounts
24 - 0.91" / 23.0 mm 90.0 cal guns - 0.44lbs / 0.20kg shells, 8,000 per gun
     Machine guns in deck mounts, 1929 Model
     12 x Twin mounts on sides, evenly spread
      12 double raised mounts
Weight of broadside 22,875 lbs / 10,376 kg

Armour:
- Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   16.1" / 410 mm   400.92 ft / 122.20 m   18.73 ft / 5.71 m
   Ends:   1.38" / 35 mm   215.85 ft / 65.79 m   12.01 ft / 3.66 m
     Main Belt covers 100 % of normal length
     Main Belt inclined -20.00 degrees (positive = in)

- Torpedo Bulkhead - Additional damage containing bulkheads:
      1.97" / 50 mm   400.92 ft / 122.20 m   31.56 ft / 9.62 m
   Beam between torpedo bulkheads 72.18 ft / 22.00 m

- Hull Bulges:
      0.35" / 9 mm   416.67 ft / 127.00 m   22.97 ft / 7.00 m

- Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   19.7" / 500 mm   7.87" / 200 mm      16.1" / 410 mm
   2nd:   2.36" / 60 mm   1.57" / 40 mm      1.57" / 40 mm
   3rd:   0.31" / 8 mm     -           -
   4th:   0.31" / 8 mm     -           -

- Protected deck - multiple decks:
   For and Aft decks: 7.39" / 188 mm
   Forecastle: 1.57" / 40 mm Quarter deck: 5.51" / 140 mm

- Conning towers: Forward 6.50" / 165 mm, Aft 6.50" / 165 mm

Machinery:
   Oil fired boilers, steam turbines,
   Electric motors, 4 shafts, 66,176 shp / 49,367 Kw = 23.00 kts
   Range 7,068nm at 16.00 kts
   Bunker at max displacement = 4,924 tons

Complement:
   1,539 - 2,002

Cost:
   £17.207 million / $68.828 million

Distribution of weights at normal displacement:
   Armament: 4,532 tons, 10.1 %
     - Guns: 4,532 tons, 10.1 %
   Armour: 16,608 tons, 37.0 %
     - Belts: 5,610 tons, 12.5 %
     - Torpedo bulkhead: 922 tons, 2.1 %
     - Bulges: 125 tons, 0.3 %
     - Armament: 2,789 tons, 6.2 %
     - Armour Deck: 6,809 tons, 15.2 %
     - Conning Towers: 353 tons, 0.8 %
   Machinery: 1,953 tons, 4.4 %
   Hull, fittings & equipment: 14,050 tons, 31.3 %
   Fuel, ammunition & stores: 5,841 tons, 13.0 %
   Miscellaneous weights: 1,856 tons, 4.1 %
     - Hull below water: 811 tons
     - Bulge void weights: 180 tons
     - Hull above water: 78 tons
     - On freeboard deck: 174 tons
     - Above deck: 613 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     70,588 lbs / 32,018 Kg = 28.1 x 17.1 " / 435 mm shells or 13.0 torpedoes
   Stability (Unstable if below 1.00): 1.36
   Metacentric height 10.6 ft / 3.2 m
   Roll period: 16.1 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.36
   Seaboat quality (Average = 1.00): 1.21

Hull form characteristics:
   Hull has rise forward of midbreak,
     a normal bow and a round stern
   Block coefficient (normal/deep): 0.648 / 0.650
   Length to Beam Ratio: 4.95 : 1
   'Natural speed' for length: 24.84 kts
   Power going to wave formation at top speed: 51 %
   Trim (Max stability = 0, Max steadiness = 100): 58
   Bow angle (Positive = bow angles forward): 12.00 degrees
   Stern overhang: -6.56 ft / -2.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
     - Forecastle:   17.50 %, 27.56 ft / 8.40 m, 24.77 ft / 7.55 m
     - Forward deck:   25.00 %, 24.77 ft / 7.55 m, 24.77 ft / 7.55 m
     - Aft deck:   40.00 %, 16.73 ft / 5.10 m, 16.73 ft / 5.10 m
     - Quarter deck:   17.50 %, 16.73 ft / 5.10 m, 16.73 ft / 5.10 m
     - Average freeboard:      20.34 ft / 6.20 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 98.9 %
      - Above water (accommodation/working, high = better): 132.9 %
   Waterplane Area: 54,158 Square feet or 5,031 Square metres
   Displacement factor (Displacement / loading): 105 %
   Structure weight / hull surface area: 221 lbs/sq ft or 1,081 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.94
      - Longitudinal: 1.71
      - Overall: 1.00
   Adequate machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform
   Good seaboat, rides out heavy weather easily

Work in Progress- tinker with Belt and deck heights.

The Asi class is rated for 23 knots, giving it a 2 knot advantage over the older elements of the Byzantine line.

Introducing the inclined belt in service, along with the 435L47 gun, the class introduces a new level of protection and lethality, while retaining a speed painstakingly slow to outsiders.

In typical Parthian fashion, they expect to have an ...expansive... Immunity Zone.
From 15km to 29km, complete
From 13km to 30+km, partial
magazines : from ~8km +

Armor Scheme:

Conceding the chance of a con is low, and that actually stopping a main battery round with no concussive damage or ejecta unlikely, the conning armor is reduced to 165mm, sufficient for most round and all splinters. The Aux con is armored to the same level. A CIC below the main armored deck is provided.

Deck

The Deck armor over the citadel is :
140mm main - 4,492t
40mm splinter protective deck - 1,283
75mm over magazines. - 250

40mm protective deck forward - 117
140mm protective deck aft - 666
(each with +35mm slopes)

187.8mm Total Tonnage : 6,809
Total tonnage allocated : 6,999

The 140mm main deck caps the belt armor system and is meant to stop shells at all reasonable ranges. This is backed by a substantial 40mm splinter deck. This is meant to stop high order splinters from either the belt or deck from penetrating the vitals.

Forward, a 40mm protective deck guards the bow, and aft a 140mm protective deck guards the stern.

Vertical Protection Effective : 140 + 40/2 = 160mm
Over magazines : +75/2 = 197.5 mm

Belt
Exterior 80mm decapping plate, interior 330mm belt inclined 20degrees.

Waterline effective
80mm decapping, 330 inclined, 40mm Protective Deck, 57mm TDS
80/2 + 330/0.8 (decapped pen) + 40*1.5/2 + 57/2=
520.5mm at waterline
558mm at magazines at waterline.

An exterior 80mm decapping plate also serves to defeat HE shells and bombs.

Underwater, below the exterior belt, is the exterior bulge.

The interior belt is sloped at 20 degrees and is 330mm above the waterline, tapering once 1m below the waterline down to 230mmm.

Belt Armor Math:
a) determine volume of decapping plate, volume of main belt & tapered section for full height.
tapering will reduce volume compared to full thickness.

b) Goal is to show on SS full thickness, but adjust height for same volume. So Volume/Full thickness = height

C) Then apply the COS for the inclined belt to the height, to get adjusted height. Since Decapping plate is not inclined, this will be slightly high.

The exterior shell is a 80mm homogeneous decapping plate from +2.65 to -3
452 = 5.65 * 80

The interior belt is inclined outwards at 20degrees and tapers
Starting at 330mm above water from +2.65m to -1m below waterline, then
From -1m to -3m it tapers to 230mm.

The Main Belt Math :
untapered portion
1204.5 = (2.65 to -1) x 330mm
tapered portion
460 = (-1 to -3) x 230mm
110 = (-1 to -3) x 1/2 x (330-230)

Subtotal
= 1774.5 main belt

Adjust for inclined = 1774.5/cos(20) = 1888.38
+452 for decapping plate
----
2340.38 plate volume

At a thickness of 80+330 = 410mm
This is a plate height of :
2340.38/410 = 5.708 = 5.71

WERKIN
Decks to 140

2.65m to -3m : total 5.65

Decapping Volume : 2.65

The entire inner belt is outsloped

The Bulge goes to the bottom of the exterior plate.

TDS
The TDS rises to 0.2m above WL, sealing to the bottom of the splinter deck.
With the exterior bulge and interior room, it is 8m deep.

9mm bulge skin
1.5m Void bulge
Hull
1.5m Void
mild bulkhead
2m Fuel
mild bulkhead
2m Fuel
1x 20mm STS
2m Void
1x 30mm STS

The TDS rises behind the lower main belt, sealing to the botom of the splinter deck. The TDS with its
hull material, and 1x19mm STS middle bulkhead and 2x19mm STS holding bulkhead is expected to be proof against splinters.
Further, the TDS system serves as a flooding barrier if the outer decapping plate or main belt are pierced or pushed in.

Decks
7.55 Forecastle deck
5.10 Weather Deck - unarmored
2.65 Battery Deck, 145mm Armor
0.20 Top Protective Splinter Deck, 40mm Armor, Top TDS.
-2.3 Bottom edge Splinter Deck
-3.0 Bottom Main Belt.

-5.8
-8.8 Engineering
-9.5 Keel, Double Bottom

Misc Wt
180t Resv

453t FC 1930
25t LR Radio
0t SR Radio
10t Air SR Radio
25t Hulesmeyer station keeping
25t Night Fight tower
75t Admirals Quarters

OD
5t - Paravanes
100t - 4x Ftr/ scout float
10t - 2x CAT
20t - Hangers in stern
39t - Ext Fire Suppression

HAW
39t Ext Fire Suppression
39t Climate Control

HBW
100t - Combat information Center
190 tons Torpedo Nets
482 tons Turbo-Electric
39t Enhanced Pumps

60t -Aux Diesel-Electric plant. - Last 168nm of fuel is Diesel for this . sufficient for ~7knots

Kaiser Kirk · April 20, 2024, 08:36:40 PM

This is Imulhu, which is the 26knot version.
Those 3 knots, on the same guns/armor "cost" 6,000 tons.

OR..the slightly less well armored Wirozag could be used,
but the longer Imulhu also has 1.2 seakeeping while the Wirozag does not.

QuoteIlmulhu, Parthian Battleship laid down 1932

Displacement:
   45,000 t light; 48,229 t standard; 51,043 t normal; 53,295 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (711.69 ft / 705.38 ft) x 114.83 ft (Bulges 124.67 ft) x (31.50 / 32.77 ft)
   (216.92 m / 215.00 m) x 35.00 m (Bulges 38.00 m) x (9.60 / 9.99 m)

Armament:
8 - 17.13" / 435 mm 47.0 cal guns - 2,711.69lbs / 1,230.00kg shells, 140 per gun
     Breech loading guns in turret on barbette mounts, 1930 Model
     2 x 4-gun mounts on centreline, evenly spread
20 - 4.53" / 115 mm 47.0 cal guns - 55.12lbs / 25.00kg shells, 400 per gun
     Dual purpose guns in deck and hoist mounts, 1931 Model
     8 x 2-gun mounts on side ends, evenly spread
      4 raised mounts - superfiring
     2 x 2-gun mounts on centreline ends, evenly spread
      2 double raised mounts
40 - 1.46" / 37.0 mm 70.0 cal guns - 1.73lbs / 0.78kg shells, 6,000 per gun
     Anti-air guns in deck and hoist mounts, 1929 Model
     10 x 2-gun mounts on sides, evenly spread
      8 raised mounts
24 - 0.91" / 23.0 mm 90.0 cal guns - 0.43lbs / 0.20kg shells, 8,000 per gun
     Machine guns in deck mounts, 1929 Model
     12 x Twin mounts on sides, evenly spread
      12 double raised mounts
Weight of broadside 22,875 lbs / 10,376 kg

Armour:
- Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   16.1" / 410 mm   458.50 ft / 139.75 m   18.73 ft / 5.71 m
   Ends:   1.38" / 35 mm   246.85 ft / 75.24 m   12.01 ft / 3.66 m
     Main Belt covers 100 % of normal length
     Main Belt inclined -20.00 degrees (positive = in)

- Torpedo Bulkhead - Additional damage containing bulkheads:
      1.97" / 50 mm   458.50 ft / 139.75 m   30.84 ft / 9.40 m
   Beam between torpedo bulkheads 75.46 ft / 23.00 m

- Hull Bulges:
      0.35" / 9 mm   416.67 ft / 127.00 m   22.97 ft / 7.00 m

- Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   19.7" / 500 mm   7.87" / 200 mm      16.1" / 410 mm
   2nd:   2.36" / 60 mm   1.57" / 40 mm      1.57" / 40 mm
   3rd:   0.31" / 8 mm     -           -
   4th:   0.31" / 8 mm     -           -

- Protected deck - single deck:
   For and Aft decks: 7.36" / 187 mm
   Forecastle: 1.57" / 40 mm Quarter deck: 5.51" / 140 mm

- Conning towers: Forward 6.50" / 165 mm, Aft 6.50" / 165 mm

Machinery:
   Oil fired boilers, steam turbines,
   Electric motors, 4 shafts, 109,000 shp / 81,314 Kw = 26.00 kts
   Range 6,760nm at 16.00 kts
   Bunker at max displacement = 5,066 tons

Complement:
   1,697 - 2,207

Cost:
   £18.966 million / $75.864 million

Distribution of weights at normal displacement:
   Armament: 4,532 tons, 8.9 %
     - Guns: 4,532 tons, 8.9 %
   Armour: 18,326 tons, 35.9 %
     - Belts: 6,271 tons, 12.3 %
     - Torpedo bulkhead: 1,030 tons, 2.0 %
     - Bulges: 125 tons, 0.2 %
     - Armament: 2,839 tons, 5.6 %
     - Armour Deck: 7,675 tons, 15.0 %
     - Conning Towers: 385 tons, 0.8 %
   Machinery: 3,217 tons, 6.3 %
   Hull, fittings & equipment: 16,657 tons, 32.6 %
   Fuel, ammunition & stores: 6,044 tons, 11.8 %
   Miscellaneous weights: 2,267 tons, 4.4 %
     - Hull below water: 1,164 tons
     - Bulge void weights: 220 tons
     - Hull above water: 90 tons
     - On freeboard deck: 180 tons
     - Above deck: 613 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     83,086 lbs / 37,687 Kg = 33.1 x 17.1 " / 435 mm shells or 14.2 torpedoes
   Stability (Unstable if below 1.00): 1.32
   Metacentric height 10.2 ft / 3.1 m
   Roll period: 16.4 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.41
   Seaboat quality (Average = 1.00): 1.20

Hull form characteristics:
   Hull has rise forward of midbreak,
     a normal bow and a round stern
   Block coefficient (normal/deep): 0.645 / 0.647
   Length to Beam Ratio: 5.66 : 1
   'Natural speed' for length: 26.56 kts
   Power going to wave formation at top speed: 52 %
   Trim (Max stability = 0, Max steadiness = 100): 58
   Bow angle (Positive = bow angles forward): 12.00 degrees
   Stern overhang: -6.56 ft / -2.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
     - Forecastle:   20.00 %, 29.69 ft / 9.05 m, 27.23 ft / 8.30 m
     - Forward deck:   46.00 %, 27.23 ft / 8.30 m, 24.77 ft / 7.55 m
     - Aft deck:   19.00 %, 16.73 ft / 5.10 m, 16.73 ft / 5.10 m
     - Quarter deck:   15.00 %, 16.73 ft / 5.10 m, 16.73 ft / 5.10 m
     - Average freeboard:      23.29 ft / 7.10 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 96.7 %
      - Above water (accommodation/working, high = better): 161.5 %
   Waterplane Area: 61,765 Square feet or 5,738 Square metres
   Displacement factor (Displacement / loading): 108 %
   Structure weight / hull surface area: 221 lbs/sq ft or 1,078 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.95
      - Longitudinal: 1.53
      - Overall: 1.00
   Adequate machinery, storage, compartmentation space
   Excellent accommodation and workspace room
   Ship has slow, easy roll, a good, steady gun platform

The Imulhu class is rated for 26 knots, matching both the Expeditionary fleet, and the most recent Byzantine line ships.

Introducing the inclined belt in service, along with the 435L47 gun, the class introduces a new level of protection and lethality, while retaining a speed painstakingly slow to outsiders.

In typical Parthian fashion, they expect to have an ...expansive... Immunity Zone.
From 15km to 29km, complete
From 13km to 30+km, partial
magazines : from ~8km +

Armor Scheme:

Conceding the chance of a con is low, and that actually stopping a main battery round with no concussive damage or ejecta unlikely, the conning armor is reduced to 165mm, sufficient for most round and all splinters. The Aux con is armored to the same level. A CIC below the main armored deck is provided.

Deck

The Deck armor over the citadel is :
140mm main - 5159t
40mm splinter protective deck - 1,474
75mm over magazines. - 251

40mm protective deck forward - 161
140mm protective deck aft - 628
(each with +35mm slopes)
----
Subtotal : 7673

186.9mm Total Tonnage : 7675

The 140mm main deck caps the belt armor system and is meant to stop shells at all reasonable ranges. This is backed by a substantial 40mm splinter deck. This is meant to stop high order splinters from either the belt or deck from penetrating the vitals.

Forward, a 40mm protective deck guards the bow, and aft a 140mm protective deck guards the stern.

Vertical Protection Effective : 140 + 40/2 = 160mm
Over magazines : +75/2 = 197.5 mm

Belt
Exterior 80mm decapping plate, interior 330mm belt inclined 20degrees.

Waterline effective
80mm decapping, 330 inclined, 40mm Protective Deck, 57mm TDS
80/2 + 330/0.8 (decapped pen) + 40*1.5/2 + 57/2=
520.5mm at waterline
558mm at magazines at waterline.

An exterior 80mm decapping plate also serves to defeat HE shells and bombs.

Underwater, below the exterior belt, is the exterior bulge.

The interior belt is sloped at 20 degrees and is 330mm above the waterline, tapering once 1m below the waterline down to 230mmm.

Belt Armor Math:
a) determine volume of decapping plate, volume of main belt & tapered section for full height.
tapering will reduce volume compared to full thickness.

b) Goal is to show on SS full thickness, but adjust height for same volume. So Volume/Full thickness = height

C) Then apply the COS for the inclined belt to the height, to get adjusted height. Since Decapping plate is not inclined, this will be slightly high.

The exterior shell is a 80mm homogeneous decapping plate from +2.65 to -3
452 = 5.65 * 80

The interior belt is inclined outwards at 20degrees and tapers
Starting at 330mm above water from +2.65m to -1m below waterline, then
From -1m to -3m it tapers to 230mm.

The Main Belt Math :
untapered portion
1204.5 = (2.65 to -1) x 330mm
tapered portion
460 = (-1 to -3) x 230mm
110 = (-1 to -3) x 1/2 x (330-230)

Subtotal
= 1774.5 main belt

Adjust for inclined = 1774.5/cos(20) = 1888.38
+452 for decapping plate
----
2340.38 plate volume

At a thickness of 80+330 = 410mm
This is a plate height of :
2340.38/410 = 5.708 = 5.71

2.65m to -3m : total 5.65

Decapping Volume : 2.65

The entire inner belt is outsloped

The Bulge goes to the bottom of the exterior plate.

TDS
The TDS rises to 0.2m above WL, sealing to the bottom of the splinter deck.
With the exterior bulge and interior room, it is 8m deep.

9mm bulge skin
1.5m Void bulge
Hull
1.5m Void
mild bulkhead
2m Fuel
mild bulkhead
2m Fuel
1x 20mm STS
2m Void
1x 30mm STS

The TDS rises behind the lower main belt, sealing to the botom of the splinter deck. The TDS with its
hull material, and 1x19mm STS middle bulkhead and 2x19mm STS holding bulkhead is expected to be proof against splinters.
Further, the TDS system serves as a flooding barrier if the outer decapping plate or main belt are pierced or pushed in.

Decks
7.55 Forecastle deck
5.10 Weather Deck - unarmored
2.65 Battery Deck, 145mm Armor
0.20 Top Protective Splinter Deck, 40mm Armor, Top TDS.
-2.3 Bottom edge Splinter Deck
-3.0 Bottom Main Belt.
-5.5 1st platform dec
-8.2 Engineering
-9.2 Double Bottom
-9.5 K

Misc Wt
250t Resv

453t FC 1930
25t LR Radio
0t SR Radio
10t Air SR Radio
25t Hulesmeyer station keeping
25t Night Fight tower
75t Admirals Quarters

OD
5t - Paravanes
100t - 4x Ftr/ scout float
10t - 2x CAT
20t - Hangers in stern
45t - Ext Fire Suppression

HAW
45t Ext Fire Suppression
45t Climate Control

HBW
100t - Combat information Center
215 tons Torpedo Nets
804 tons Turbo-Electric
45t Enhanced Pumps

60t -Aux Diesel-Electrice plant. - Last 138nm of fuel is Diesel for this . sufficient for ~7knots

The Rock Doctor · April 21, 2024, 08:49:45 AM

Speaking of decapping plates, do we have a guideline on integrating them into a SS design? Or what thickness accomplishes what effect?

I won't have them until 1934, so shrugged and carried on with my 1931 battleship class...

Kaiser Kirk · April 21, 2024, 12:26:15 PM

Quote from: The Rock Doctor on April 21, 2024, 08:49:45 AMSpeaking of decapping plates, do we have a guideline on integrating them into a SS design? Or what thickness accomplishes what effect?

I won't have them until 1934, so shrugged and carried on with my 1931 battleship class...

I thought we did, wasn't able to find it.
But I did recall the source material.

Nathan Okun speaks about them while evaluating Bismarck's gun vs. various battleships on CombinedFleet
and then there's an article with a little graph on Navweaps.

Decapping plate thickness
The early concept was up to a decapping plate needed to be 1/5th of the shell size to work, with varying effectiveness beyond that point.

Looking at the little chart, it seems like he arrived at 0.17 of shell size to be effective.
So that's what I'm using.
80mm / 0.17 = 470mm aka about 1" larger than the biggest gun the Parthians know about.

That's also thick enough to protect the side hull from 'nuisance' holes....and flooding... from Bombs/non-AP shells, and cruiser shells. Which offsets one of the big negatives of an internal belt.

Only the Italians actually fitted a designed Decapping plate, the USN tried to address the external flooding issue with reinforced hull that mimics it incidentally but does not work on capital-ship level shells.

Effect
That's a little harder to pin down.
BigGun used a 0.8 penetration modifier if the shell was decapped or lacked an AP cap.
I am unsure how that was derived, but until I run across something better,
that is what I plan to use.

That is where I get the numbers above
though I do not include the outsloped belt effect,
which Logi's Ballistics does allow me to figure it out if desired. I decided that's too specific.

QuoteExterior 80mm decapping plate, interior 330mm belt inclined 20degrees.

Waterline effective
80mm decapping, 330 inclined, 40mm Protective Deck, 57mm TDS
80/2 + 330/0.8 (decapped pen) + 40*1.5/2 + 57/2=
520.5mm at waterline
558mm at magazines at waterline.

The Rock Doctor · April 21, 2024, 12:55:30 PM

Good to know, good to know...

Kaiser Kirk · April 22, 2024, 01:12:50 AM

A somewhat antiquated example of a never build 500t torpedo boat from 1925

QuoteSea Hornet, Parthian Torpedo Attack laid down 1925

Displacement:
   500 t light; 516 t standard; 552 t normal; 581 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (258.23 ft / 255.91 ft) x 24.05 ft x (8.27 / 8.55 ft)
   (78.71 m / 78.00 m) x 7.33 m x (2.52 / 2.61 m)

Armament:
1 - 3.54" / 90.0 mm 50.0 cal gun - 24.25lbs / 11.00kg shells, 200 per gun
     Quick firing gun in deck mount, 1925 Model
     1 x Single mount on centreline, forward deck forward
2 - 2.24" / 57.0 mm 60.0 cal guns - 6.61lbs / 3.00kg shells, 300 per gun
     Anti-air guns in deck mounts, 1925 Model
     2 x Single mounts on centreline ends, evenly spread
      2 raised mounts
Weight of broadside 37 lbs / 17 kg

Armour:
- Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.12" / 3 mm     -           -

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 1 shaft, 14,687 shp / 10,956 Kw = 30.00 kts
   Range 2,400nm at 12.00 kts
   Bunker at max displacement = 65 tons

Complement:
   56 - 74

Cost:
   £0.193 million / $0.770 million

Distribution of weights at normal displacement:
   Armament: 8 tons, 1.5 %
     - Guns: 8 tons, 1.5 %
   Armour: 0 tons, 0.0 %
     - Armament: 0 tons, 0.0 %
   Machinery: 280 tons, 50.6 %
   Hull, fittings & equipment: 174 tons, 31.5 %
   Fuel, ammunition & stores: 52 tons, 9.4 %
   Miscellaneous weights: 38 tons, 6.9 %
     - On freeboard deck: 36 tons
     - Above deck: 2 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     190 lbs / 86 Kg = 8.5 x 3.5 " / 90 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.22
   Metacentric height 0.9 ft / 0.3 m
   Roll period: 10.9 seconds
   Steadiness   - As gun platform (Average = 50 %): 51 %
         - Recoil effect (Restricted arc if above 1.00): 0.12
   Seaboat quality (Average = 1.00): 1.02

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a cruiser stern
   Block coefficient (normal/deep): 0.380 / 0.386
   Length to Beam Ratio: 10.64 : 1
   'Natural speed' for length: 16.00 kts
   Power going to wave formation at top speed: 67 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 12.00 degrees
   Stern overhang: 0.00 ft / 0.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
     - Forecastle:   20.00 %, 10.93 ft / 3.33 m, 10.93 ft / 3.33 m
     - Forward deck:   20.00 %, 10.93 ft / 3.33 m, 10.93 ft / 3.33 m
     - Aft deck:   45.00 %, 10.93 ft / 3.33 m, 10.93 ft / 3.33 m
     - Quarter deck:   15.00 %, 10.93 ft / 3.33 m, 10.93 ft / 3.33 m
     - Average freeboard:      10.93 ft / 3.33 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 167.9 %
      - Above water (accommodation/working, high = better): 131.2 %
   Waterplane Area: 3,532 Square feet or 328 Square metres
   Displacement factor (Displacement / loading): 55 %
   Structure weight / hull surface area: 24 lbs/sq ft or 115 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 2.25
      - Overall: 0.58
   Cramped machinery, storage, compartmentation space
   Excellent accommodation and workspace room

Warning: Beam between bulkheads too wide

1 FC
0t SR Radio

1 NF Binocs, signals, running lights

4 TT3 21" 3t

Kaiser Kirk · April 22, 2024, 01:21:33 AM

The Pesh-Kabr was probably the last 500 ton TB I considered- build space you know.
However it was designed from the concept that I would have 1 per 4-8 MTBs
interdicting the sealanes vs. mercantile traffic, and only engage actual
Battlefleets at night, or at amphibious landing spots. Part of the concept
was the MTB force was largely best as an harassment force and fleet in being.
That did mean seakeeping could be sacrificed, after all amphib TFs do not land in storms.

Generally on my 500 ton designs, I do not view HW torps as needed, I figure any hole under the waterline is advantageous to my battlefleet, and most non-capital ships have no TDS anyhow so more torpedoes are more important than heavier torpedoes.

So, the ability to act while cut off (coal) was built in.

QuotePesh-Kabz, Parthian Torpedo Boat Leader laid down 1924

Displacement:
   459 t light; 475 t standard; 544 t normal; 599 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
   (261.88 ft / 258.37 ft) x 24.05 ft x (7.87 / 8.41 ft)
   (79.82 m / 78.75 m) x 7.33 m x (2.40 / 2.56 m)

Armament:
2 - 3.54" / 90.0 mm 50.0 cal guns - 24.25lbs / 11.00kg shells, 120 per gun
     Quick firing guns in deck mounts, 1911 Model
     2 x Single mounts on centreline, forward evenly spread
      1 raised mount
1 - 2.24" / 57.0 mm 60.0 cal gun - 6.61lbs / 3.00kg shells, 300 per gun
     Anti-air gun in deck mount, 1917 Model
     1 x Single mount on centreline, aft deck centre
      1 raised mount
4 - 0.59" / 15.0 mm 70.0 cal guns - 0.11lbs / 0.05kg shells, 1,500 per gun
     Machine guns in deck mounts, 1917 Model
     2 x Twin mounts on sides forward
      2 double raised mounts
Weight of broadside 56 lbs / 25 kg

Armour:
- Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0.12" / 3 mm     -           -

Machinery:
   Coal and oil fired boilers, steam turbines,
   Geared drive, 1 shaft, 13,538 shp / 10,100 Kw = 29.51 kts
   Range 1,055nm at 21.00 kts
   Bunker at max displacement = 124 tons (23% coal)

Complement:
   56 - 73

Cost:
   £0.177 million / $0.709 million

Distribution of weights at normal displacement:
   Armament: 12 tons, 2.1 %
     - Guns: 12 tons, 2.1 %
   Armour: 1 tons, 0.1 %
     - Armament: 1 tons, 0.1 %
   Machinery: 272 tons, 50.1 %
   Hull, fittings & equipment: 141 tons, 25.9 %
   Fuel, ammunition & stores: 84 tons, 15.5 %
   Miscellaneous weights: 34 tons, 6.3 %
     - Hull void weights: 5 tons
     - On freeboard deck: 28 tons
     - Above deck: 1 tons

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     160 lbs / 73 Kg = 7.2 x 3.5 " / 90 mm shells or 0.2 torpedoes
   Stability (Unstable if below 1.00): 1.29
   Metacentric height 0.9 ft / 0.3 m
   Roll period: 10.5 seconds
   Steadiness   - As gun platform (Average = 50 %): 51 %
         - Recoil effect (Restricted arc if above 1.00): 0.16
   Seaboat quality (Average = 1.00): 0.81

Hull form characteristics:
   Hull has a flush deck,
     a normal bow and a round stern
   Block coefficient (normal/deep): 0.389 / 0.401
   Length to Beam Ratio: 10.74 : 1
   'Natural speed' for length: 16.07 kts
   Power going to wave formation at top speed: 66 %
   Trim (Max stability = 0, Max steadiness = 100): 63
   Bow angle (Positive = bow angles forward): 15.00 degrees
   Stern overhang: -3.28 ft / -1.00 m
   Freeboard (% = length of deck as a percentage of waterline length):
            Fore end,    Aft end
     - Forecastle:   20.00 %, 13.12 ft / 4.00 m, 10.83 ft / 3.30 m
     - Forward deck:   32.50 %, 10.83 ft / 3.30 m, 8.20 ft / 2.50 m
     - Aft deck:   32.50 %, 8.20 ft / 2.50 m, 8.20 ft / 2.50 m
     - Quarter deck:   15.00 %, 8.20 ft / 2.50 m, 8.20 ft / 2.50 m
     - Average freeboard:      9.34 ft / 2.85 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 167.6 %
      - Above water (accommodation/working, high = better): 108.1 %
   Waterplane Area: 3,588 Square feet or 333 Square metres
   Displacement factor (Displacement / loading): 56 %
   Structure weight / hull surface area: 22 lbs/sq ft or 108 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.50
      - Longitudinal: 1.21
      - Overall: 0.55
   Cramped machinery, storage, compartmentation space
   Adequate accommodation and workspace room
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

Warning: Beam between bulkheads too wide

Trial Speed Bonus : 2.49
+29.51
----
32.0

This is meant as a Parthian Torpedo Boat Leader.
This will serve as a dedicate lead vessel for MTBs,
providing the long range navigation and radio facilities they lack.

Seakeeping is minimal, as they expect choose when they go to sea.

Power :
75% Oil fired boilers, 25% coal fired
10050 / 3350

29.505 kts : 13,400shp
27.556 kts :10050shp - max oiled fired
20.961 kts : 3350shp - max coal fired

7540 shp = 75% oil power = 25.706 kts
5025 shp = 50% oil power = 23.247 kts
3350 shp = 33% oil power = 20.961 kts

Fuel : 122 tons
93.9t : Oil
32.1t : Oil-sprayed coal (10/90)

Range :
27.5kts : 1.0 Seakeeping
25.6kts : 1.2 Seakeeping
22.5 kts : 1.5 Seakeeping

Range (without gearing bonus_:
373nm, 12hrs at 29.505 - All Boilers
3070nm 219hrs / 9days/ at 14knts

Just Oil Fired
350nm, 13hrs at 27.5 kts, oil fired
440nm, 17hrs at 25.5 kts, oil fired.
565nm, 24hrs at 23.5 kts, oil fired

Just Oil-sprayed Coal
1550nm @ 10knts : oil-sprayed coal.

Misc Weight :
5t Const Reserve

0t SR Radio
1.2t FC 1918 - Rangefinders, TDC

10t - Squadron Leader plot room
5t : NF gear

18t : 2TT3 Torpedoes 21"

{/quote]

TacCovert4 · April 22, 2024, 09:57:43 AM

To ask, vis a vis the 18in, 21in, and 21in HW, were you considering all of them to have roughly the same effective range from a platform like a DD/GTB? My reasoning for going big on torpedoes is that something like a large torpedo boat gets an edge over MTBs at night for the range at which they can launch their torpedoes accurately. Which has also made it difficult to get enough torpedoes on one at 500t to be viable and also have enough speed.

A hypothetical 20t dedicated to torpedoes would net the following:

2 Quintuple launchers of 18in torpedoes
2 Triple Launchers of 21in Torpedoes
1 Quintuple launcher of 21in HW Torpedoes
1 Quad launcher of 24in Torpedoes

I concur that if you have the choice between extremely powerful torpedoes and larger spreads on target, you'd want the larger spreads in this case. Just trying to figure out if you're getting the effective range to make it work.

Kaiser Kirk · April 22, 2024, 08:47:19 PM

Quote from: TacCovert4 on April 22, 2024, 09:57:43 AMTo ask, vis a vis the 18in, 21in, and 21in HW, were you considering all of them to have roughly the same effective range from a platform like a DD/GTB? My reasoning for going big on torpedoes is that something like a large torpedo boat gets an edge over MTBs at night for the range at which they can launch their torpedoes accurately.

All of these should be full ship-size torpedoes. Planes and MTBs will be presume to have - whatever they had.

Further I long ago noted that the Torpedo Tech tree focuses on the internals of of the torpedo,
independent of size. While the Design guidelines indicate sizes are unlocked at certain points.

So if I really wanted, I could choose to field a 16" oxygen propelled advanced warhead torpedo.
Instead I expect my 18" Torpedoes to have 'advanced wet heater engines, advanced warheads, and either advanced contact or primitive magnetic (contact in my case)'.

Figuring out how that all works never rose high enough on my 'to do' list. Heck I just finally got the gun research tool up and the shell pen updated !
But I did expect the range on a 16" to be inadequate, and the warheads were really small too.

So no, that won't give them the same range as a 21", the latter has more room for fuel.
However, I do not consider very long range on torpedoes as being very usable.
So the effective range I wish to use them is closer,

Simply glancing at the Brit WWI 18" vs 21", it looks like about 80% of the range, while ~10,000@30knots looks about right, so 8000 @ 30 would be ballpark - and that is about the outer range I want to launch at. I would like to launch 6000-7000. So that's ok.

At that point, my goal with these attacks is to put holes below the waterline.
The more shots I take, the higher the chance I'll hit. The vast majority of targets out there do not have a TDS. Against a merchant or amphious ship at a beachhead, 18" is devastating. Even ships WITH a TDS, the hole tends to force speeds under 20knots or else internal bulkheads have issues - example North Carolina, down to 18max from 28. Even a Parthian battleship can run that down. Ironically underwater tubes couldn't be used at over 20knots for the same reason.

I've tried in the various wars to underscore that the formula SK uses makes distance very important. There were noticeable drops in hit rates between 2000 and ~6000m.
Further, the 'hit' rate drops madly when they get Bow-on....not surprising.
The Glowworm vs. Hipper I referenced was 5 torps at 870yards, vs. a bow-on Hipper..5 misses.
While historical navies thought ramming a torpedo could make them fail or glance off, that curiously is not reflected.

It has long bounced about on my to-do list to reformulate the formula for TIME, so that faster torpedoes see a distinct benefit. At that point Range @ Fast setting may be more imperative.

For MTBs, I presume they have no rangefinder/plotting table, can't change range @ speed, though I think they had a simple slide-rule type thing that one has to guess at the inputs for . Still, they need to close in. I know I've used both 3000 and 6000m as a launch point, but I think 3-4000m is likely more "reasonable" as that was the expected battle range pre-rangefinder, while a vessel with fire control I think gets a bonus for that, and combines with the choice of ranges.
Plus MTBS are very limited in sea states they can operate in, though they can operate in basically the same sea states amphibious landings can lower boats at reasonable rates.

From the Sino-Japanese war, getting TBs in close at night worked.Foxy adjusted his tactics to have screens, which actually worked quite well. I've learned enough since then that I did have the MTBs a little too fast- sorry Fox, probably not the difference maker though.

But the daytime engagements have not gone well- in part because the defensive fire is not saturated. So you see the Pesh-kabr concept, and the amalgamation of Parthian MTBs into larger formations they were meant to lead in night attacks to saturate defenses.

Ok, that was a lot.
Did I actually answer anything?

So part of the task would be to lead the gagge

TacCovert4 · April 22, 2024, 09:07:23 PM

Ok, so an 18in torpedo could still have sufficient range.

As we move into the 30s I'm looking at night launches around 10km or so, improving hit rate by surprise.

Like you noted, MTBs typically shoot smaller torpedoes, and they do so with the most basic of aiming systems, mostly mk1 eyeball. Overall I think 4km would be a max range launch from an MTB in anything less than a full squadron saturation attack, with aimed launches being between 1.5 and 2.5km.

At least that's how I treat it, and why if I can make it worthwhile I'll do a big TB, because it brings a significant capability to the battlespace. Mostly that it has FC, can do a larger and more controlled launch and even coordinate amongst multiple ships....and they can house NF Devices to allow better night operations. Plus a 500t ship is a hard target to find at night.

Kaiser Kirk · April 22, 2024, 09:08:56 PM

Long long ago in drydocks far away, the Parthians lay down 4 cruisers on the same hull design that were meant to be matchup challenges, able to raid the sealanes across the globe. A mix of 28 and 30.25 knots, 180 and 165mm guns, varying armors, a ship class optimized to catch and beat any of them would be quite large in displacement. There was even the idea raiding into the Med through the Gates of Gibraltar from Cape Verde, forcing the Byzantines to guard their rear areas - that entire concept, and drive for Cape Verde, died with the Malta treaty.

So now, 20 years later, they can be scrapped or refurbished.

The Vatu/Vanu ...in hindsight...might have had trouble fitting 2 x MTB-A (meant for night raids on enemy harbors) on the deck. I'm guessing they had a flying bridge over them to reclaim some space.

But now, with the Parthians trying to field Seaplane Cruisers, this space seems like a reasonable place to host seaplanes.

Costs

Base : 1.4992

A) Armanent & Machinery
405 Guns & mounts
2024 machinery
----
2429

$ 4.858
BP 2.429

B) Armor & Functional Misc Wt
114 t Weapon armor
475t Hull armor
385t F Misc Wt (585-150)
----
974

$ 0.974
BP 0.974

C) Hull
7392/5000
---
$ 1.4784

D) Bunkers and Magazines
1815 - bunker
322 - magazines
----
2137/2000
---
$ 1.0685

Totals :

$ 9.88
BP 3.40

QuoteVaryu / Vatu, Parthian Raider laid down 1911 (Engine 1932)

Displacement:
7,392 t light; 7,892 t standard; 8,900 t normal; 9,707 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(492.13 ft / 485.56 ft) x 50.03 ft x (22.15 / 23.77 ft)
(150.00 m / 148.00 m) x 15.25 m x (6.75 / 7.24 m)

Armament:
8 - 6.50" / 165 mm 47.0 cal guns - 176.37lbs / 80.00kg shells, 240 per gun
Quick firing guns in deck and hoist mounts, 1929 Model
4 x Single mounts on centreline ends, evenly spread
2 raised mounts - superfiring
4 x Single mounts on side ends, evenly spread
8 - 3.54" / 90.0 mm 54.0 cal guns - 24.25lbs / 11.00kg shells, 600 per gun
Dual purpose guns in deck and hoist mounts, 1929 Model
4 x 2-gun mounts on side ends, evenly spread
4 raised mounts
16 - 1.46" / 37.0 mm 70.0 cal guns - 1.72lbs / 0.78kg shells, 2,600 per gun
Anti-air guns in deck and hoist mounts, 1929 Model
2 x 2 row quad mounts on sides amidships
2 raised mounts
2 x 2 row quad mounts on centreline ends, evenly spread
2 double raised mounts
24 - 0.91" / 23.0 mm 90.0 cal guns - 0.44lbs / 0.20kg shells, 5,000 per gun
Anti-air guns in deck mounts, 1929 Model
12 x Single mounts on sides, evenly spread
Weight of broadside 1,643 lbs / 745 kg

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 3.54" / 90 mm 388.45 ft / 118.40 m 8.20 ft / 2.50 m
Ends: 0.98" / 25 mm 97.08 ft / 29.59 m 8.20 ft / 2.50 m
Upper: 1.97" / 50 mm 388.45 ft / 118.40 m 8.20 ft / 2.50 m
Main Belt covers 123 % of normal length

- Hull void:
0.00" / 0 mm 0.00 ft / 0.00 m 0.00 ft / 0.00 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2.56" / 65 mm 1.38" / 35 mm 1.97" / 50 mm
2nd: 0.59" / 15 mm 0.31" / 8 mm 0.31" / 8 mm
3rd: 0.31" / 8 mm - 0.31" / 8 mm

- Armoured deck - multiple decks:
For and Aft decks: 3.15" / 80 mm
Forecastle: 1.38" / 35 mm Quarter deck: 1.77" / 45 mm

- Conning towers: Forward 1.97" / 50 mm, Aft 0.00" / 0 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 3 shafts, 68,562 shp / 51,148 Kw = 30.00 kts
Range 7,340nm at 16.00 kts
Bunker at max displacement = 1,815 tons

Complement:
457 - 595

Cost:
£0.685 million / $2.739 million

Distribution of weights at normal displacement:
Armament: 406 tons, 4.6 %
- Guns: 406 tons, 4.6 %
Armour: 1,843 tons, 20.7 %
- Belts: 730 tons, 8.2 %
- Armament: 114 tons, 1.3 %
- Armour Deck: 981 tons, 11.0 %
- Conning Tower: 18 tons, 0.2 %
Machinery: 2,024 tons, 22.7 %
Hull, fittings & equipment: 2,585 tons, 29.0 %
Fuel, ammunition & stores: 1,508 tons, 16.9 %
Miscellaneous weights: 535 tons, 6.0 %
- Hull below water: 56 tons
- Hull void weights: 150 tons
- Hull above water: 16 tons
- On freeboard deck: 213 tons
- Above deck: 100 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
9,837 lbs / 4,462 Kg = 71.8 x 6.5 " / 165 mm shells or 1.4 torpedoes
Stability (Unstable if below 1.00): 1.05
Metacentric height 1.9 ft / 0.6 m
Roll period: 15.1 seconds
Steadiness - As gun platform (Average = 50 %): 53 %
- Recoil effect (Restricted arc if above 1.00): 0.80
Seaboat quality (Average = 1.00): 1.03

Hull form characteristics:
Hull has rise forward of midbreak,
a ram bow and a round stern
Block coefficient (normal/deep): 0.579 / 0.588
Length to Beam Ratio: 9.70 : 1
'Natural speed' for length: 22.04 kts
Power going to wave formation at top speed: 61 %
Trim (Max stability = 0, Max steadiness = 100): 52
Bow angle (Positive = bow angles forward): 13.00 degrees
Stern overhang: -6.56 ft / -2.00 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 15.00 %, 26.57 ft / 8.10 m, 24.11 ft / 7.35 m
- Forward deck: 37.00 %, 24.11 ft / 7.35 m, 21.65 ft / 6.60 m
- Aft deck: 43.00 %, 13.45 ft / 4.10 m, 13.45 ft / 4.10 m
- Quarter deck: 5.00 %, 13.45 ft / 4.10 m, 15.09 ft / 4.60 m
- Average freeboard: 18.73 ft / 5.71 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 92.4 %
- Above water (accommodation/working, high = better): 129.4 %
Waterplane Area: 17,422 Square feet or 1,619 Square metres
Displacement factor (Displacement / loading): 114 %
Structure weight / hull surface area: 90 lbs/sq ft or 439 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.93
- Longitudinal: 1.96
- Overall: 1.00
Adequate machinery, storage, compartmentation space
Excellent accommodation and workspace room

Original Light Disp : 7496
1.00 Comp hull
Original Engines - Turbine : 2961
Original Bunker : 1815

The original design shipped 2 x MTBs side by side amidships on a boat deck.
This space now is converted to a hanger for floatplanes to make this a Seaplane Cruiser.

Replace 180 & 165 with 180L47 with 85kg shell in PA hoists
Replace 4x T1 90AA with 4x T2 90AA
Add 4x Quad 37mm
Add 23mm

Replace Engine : 2,024
Replace bunker : 1815
Replace Misc Wt :
Functional : 385
Non Functional : 150
Reshaped forecastle (bow).

Armor :
Vertical (25/2 + 30+(15*.8)) = 12.5+ 30+12= 54.5mm

412t - Add 35mm deck over upper belt.
192t - Laminate 15mm onto armor deck.
---
475t

Costs

Base : 1.4992

A) Armanent & Machinery
405 Guns & mounts
2024 machinery
----
2429

$ 4.858
BP 2.429

B) Armor & Functional Misc Wt
114 t Weapon armor
475t Hull armor
385t F Misc Wt (585-150)
----
974

$ 0.974
BP 0.974

C) Hull
7392/5000
---
$ 1.4784

D) Bunkers and Magazines
1815 - bunker
322 - magazines
----
2137/2000
---
$ 1.0685

Totals :

$ 9.88
BP 3.40

reserve : 150

AD
50t - FC 1930
25t - LR Radio
0t - SR Radio
25t - Searchlight tower (NF)
25t - Hulesmeyer device

OD
5t - Paravanes
10t - Cross ship catapult
10t - 2x waist catapults
150t - Provision 6 armed floatplanes (2 ftr, 4 Scout)
30t - Hanger
8t - Enhanced Fire Suppression

HAW
8t - CO2 compressor AC
8t - Enhanced Fire suppresion

HBW
8t - Enhanced pumps
8t - Enhanced Fire Suppresion
15t- Aircraft fuel, Doublewall tank
10t - Aircraft armanents
15t - Enhanced Hydrophones

Forecastle above weather deck
Upper belt covers from Weather deck to Armor Deck
Belt Armor covers from Armor deck to 2nd Deck

+6.10 : Forecastle Deck
+3.60 : Weather Deck, Top upper belt
+1.20m Armor Deck, Top main belt
-1.30m : 2nd Deck, bottom main belt
-3.80m : 1st Deck
-6.30m : Bilges
Bilges : -6.3m