1920s Costal battleship design challenge.

[JSB]

My ship was primarily designed to defend the DEI (from the IJN, mostly 8inch CAs).

I have only shown what can be learned by outside observers and publicity announcements. (not necessarily to be trusted ).

I have changed the AA guns to newer ones, the ammo is for space to fit more AA guns later (as is the 300t misc weight).

I have decided I don't need float planes as I will be fighting near to my islands with flying boats & land planes and I also don't need much range.

What do you think ?.(before and after reading below?)
JSB


Dutch CA killer, Netherlands Coastal CA killer laid down 1929

Displacement:
11,318 t light; 11,906 t standard; 12,760 t normal; 13,443 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(630.98 ft / 630.00 ft) x 72.00 ft x (20.00 / 20.77 ft)
(192.32 m / 192.02 m) x 21.95 m x (6.10 / 6.33 m)

Armament:
6 - 11.00" / 279 mm 45.0 cal guns - 671.18lbs / 304.44kg shells, 100 per gun
Breech loading guns in turret on barbette mounts, 1929 Model
2 x Triple mounts on centreline, evenly spread
6 - 6.00" / 152 mm 45.0 cal guns - 108.93lbs / 49.41kg shells, 250 per gun
Breech loading guns in turret on barbette mounts, 1929 Model
2 x Triple mounts on centreline, evenly spread
2 raised mounts
4 - 3.46" / 88.0 mm 45.0 cal guns - 20.97lbs / 9.51kg shells, 400 per gun
Anti-air guns in deck mounts, 1929 Model
4 x Single mounts on sides, evenly spread
Weight of broadside 4,764 lbs / 2,161 kg

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 4.00" / 102 mm 348.00 ft / 106.07 m 12.00 ft / 3.66 m
Ends: Unarmoured
Main Belt covers 85 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 4.00" / 102 mm 2.50" / 64 mm 4.00" / 102 mm
2nd: 4.00" / 102 mm 2.50" / 64 mm 4.00" / 102 mm
3rd: 1.00" / 25 mm - -

- Armoured deck - single deck:
For and Aft decks: 2.50" / 64 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 65,407 shp / 48,793 Kw = 30.00 kts
Range 5,000nm at 15.00 kts
Bunker at max displacement = 1,537 tons

Complement:
599 - 780

Cost:
£4.478 million / $17.910 million

Distribution of weights at normal displacement:
Armament: 897 tons, 7.0 %
- Guns: 897 tons, 7.0 %
Armour: 2,368 tons, 18.6 %
- Belts: 718 tons, 5.6 %
- Armament: 466 tons, 3.7 %
- Armour Deck: 1,184 tons, 9.3 %
Machinery: 2,009 tons, 15.7 %
Hull, fittings & equipment: 5,744 tons, 45.0 %
Fuel, ammunition & stores: 1,442 tons, 11.3 %
Miscellaneous weights: 300 tons, 2.4 %
- Above deck: 300 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
18,867 lbs / 8,558 Kg = 28.3 x 11.0 " / 279 mm shells or 2.3 torpedoes
Stability (Unstable if below 1.00): 1.15
Metacentric height 4.0 ft / 1.2 m
Roll period: 15.1 seconds
Steadiness - As gun platform (Average = 50 %): 56 %
- Recoil effect (Restricted arc if above 1.00): 0.64
Seaboat quality (Average = 1.00): 1.10

Hull form characteristics:
Hull has rise forward of midbreak,
a normal bow and large transom stern
Block coefficient (normal/deep): 0.492 / 0.499
Length to Beam Ratio: 8.75 : 1
'Natural speed' for length: 28.98 kts
Power going to wave formation at top speed: 52 %
Trim (Max stability = 0, Max steadiness = 100): 51
Bow angle (Positive = bow angles forward): 2.00 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 %, 28.00 ft / 8.53 m, 20.00 ft / 6.10 m
- Forward deck: 50.00 %, 20.00 ft / 6.10 m, 20.00 ft / 6.10 m
- Aft deck: 15.00 %, 14.00 ft / 4.27 m, 14.00 ft / 4.27 m
- Quarter deck: 15.00 %, 14.00 ft / 4.27 m, 14.00 ft / 4.27 m
- Average freeboard: 18.84 ft / 5.74 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 83.2 %
- Above water (accommodation/working, high = better): 184.6 %
Waterplane Area: 31,193 Square feet or 2,898 Square metres
Displacement factor (Displacement / loading): 117 %
Structure weight / hull surface area: 139 lbs/sq ft or 678 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.96
- Longitudinal: 1.34
- Overall: 1.00
Excellent machinery, storage, compartmentation space
Excellent accommodation and workspace room

Edit - I didn't notice the 6inch are not in turrets but I can swap using up the ammo (it works with 100main RPG and 250 6 inch)

[denodon]

Talking about the DEI, here is a WIP of one for them that I've been working on, albeit a fair bit older. Kinda thinking in terms of a WW1 or before design not completed until after that war. Rather conservative design as you don't want fancy new tech that can't be supported from home on the other side of the world.



Unnamed, Country Coastal Defence Ship laid down 1920

Displacement:
7,190 t light; 7,535 t standard; 7,998 t normal; 8,368 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(415.00 ft / 406.00 ft) x 64.00 ft x (21.00 / 21.74 ft)
(126.49 m / 123.75 m) x 19.51 m x (6.40 / 6.63 m)

Armament:
4 - 11.10" / 282 mm 42.5 cal guns - 665.40lbs / 301.82kg shells, 100 per gun
Breech loading guns in deck and hoist mounts, 1910 Model
2 x 2-gun mounts on centreline, evenly spread
6 - 4.70" / 119 mm 45.0 cal guns - 52.36lbs / 23.75kg shells, 200 per gun
Breech loading guns in deck mounts, 1918 Model
6 x Single mounts on sides, evenly spread
4 - 1.58" / 40.0 mm 39.0 cal guns - 1.85lbs / 0.84kg shells, 720 per gun
Quick firing guns in deck mounts, 1920 Model
4 x Single mounts on sides, evenly spread
4 raised mounts
Weight of broadside 2,983 lbs / 1,353 kg

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 9.00" / 229 mm 228.00 ft / 69.49 m 14.00 ft / 4.27 m
Ends: Unarmoured
Upper: 4.00" / 102 mm 228.00 ft / 69.49 m 9.00 ft / 2.74 m
Main Belt covers 86 % of normal length

- Torpedo Bulkhead - Additional damage containing bulkheads:
6.00" / 152 mm 228.00 ft / 69.49 m 5.00 ft / 1.52 m
Beam between torpedo bulkheads 57.00 ft / 17.37 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 7.90" / 201 mm 6.00" / 152 mm 6.00" / 152 mm
2nd: 5.00" / 127 mm - -
3rd: 2.00" / 51 mm - -

- Armoured deck - multiple decks:
For and Aft decks: 1.80" / 46 mm

- Conning towers: Forward 7.00" / 178 mm, Aft 0.00" / 0 mm

Machinery:
Coal fired boilers, complex reciprocating steam engines,
Direct drive, 2 shafts, 15,997 ihp / 11,933 Kw = 20.72 kts
Range 4,000nm at 11.00 kts
Bunker at max displacement = 833 tons (100% coal)

Complement:
422 - 549

Cost:
£1.528 million / $6.111 million

Distribution of weights at normal displacement:
Armament: 574 tons, 7.2 %
- Guns: 574 tons, 7.2 %
Armour: 2,699 tons, 33.7 %
- Belts: 1,654 tons, 20.7 %
- Torpedo bulkhead: 253 tons, 3.2 %
- Armament: 305 tons, 3.8 %
- Armour Deck: 427 tons, 5.3 %
- Conning Tower: 60 tons, 0.8 %
Machinery: 1,032 tons, 12.9 %
Hull, fittings & equipment: 2,585 tons, 32.3 %
Fuel, ammunition & stores: 808 tons, 10.1 %
Miscellaneous weights: 300 tons, 3.8 %
- Hull above water: 150 tons
- Above deck: 150 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
11,909 lbs / 5,402 Kg = 17.4 x 11.1 " / 282 mm shells or 2.6 torpedoes
Stability (Unstable if below 1.00): 1.25
Metacentric height 3.9 ft / 1.2 m
Roll period: 13.7 seconds
Steadiness - As gun platform (Average = 50 %): 77 %
- Recoil effect (Restricted arc if above 1.00): 0.49
Seaboat quality (Average = 1.00): 1.53

Hull form characteristics:
Hull has a flush deck,
a ram bow and a cruiser stern
Block coefficient (normal/deep): 0.513 / 0.518
Length to Beam Ratio: 6.34 : 1
'Natural speed' for length: 20.15 kts
Power going to wave formation at top speed: 50 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 0.00 degrees
Stern overhang: -5.00 ft / -1.52 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 22.00 %, 16.50 ft / 5.03 m, 15.50 ft / 4.72 m
- Forward deck: 24.00 %, 15.50 ft / 4.72 m, 15.00 ft / 4.57 m
- Aft deck: 31.00 %, 15.00 ft / 4.57 m, 15.00 ft / 4.57 m
- Quarter deck: 23.00 %, 15.00 ft / 4.57 m, 15.50 ft / 4.72 m
- Average freeboard: 15.32 ft / 4.67 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 82.1 %
- Above water (accommodation/working, high = better): 119.5 %
Waterplane Area: 17,520 Square feet or 1,628 Square metres
Displacement factor (Displacement / loading): 107 %
Structure weight / hull surface area: 111 lbs/sq ft or 542 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.92
- Longitudinal: 2.20
- Overall: 1.00
Excellent machinery, storage, compartmentation space
Adequate accommodation and workspace room
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

[JSB]

Hi, If we are running this for a month then you only have 3 more days to enter (you know you want to !)

denodon
1) I think you have made the same problem with your turrets as me ?(deck and hoist mounts not turret on barbette mounts)
2) I'm not sure about a 1920 laid down with coal/complex reciprocating steam engines the DEI has oil but not sure about coal ? (I think Java is already turbine at that was designed in 1913)

JSB

[KHT]

Oh bugger, I have to finish my drawing...

Deno: I like it. A very typical CDS, but you do manage to get a lot of armour into it, considering the other factors. I'll have to agree with JSB's points though.
Now, I'd personaly decrease the belt by 1,5-2", and increase deck armour instead, but that's really a personal preference. I like to maintain long range against my enemies when using ships like these, and therefore I tend to prorathize deck armour to some degree.

JSB: already before reading the springsharp it was rather obvious she'd be above 10 000 tonnes in standard displacement.
I generally like the design though. I'm glad to see you've given her a relatively thick deck, even though I'd like thicker belt and turret armour(preferably above 5", anything below just isn't enough to stop a heavy cruiser shell at normal battle distances.) Regarding the belt though, you could incline it outwards(negative in Springsharp) which increases the "practical" thickness, even though the actuall one remains the same(Since shells hitting the belt will then hit it at a slightly awkward angle, it will have trouble penetrating it properly. IIRC the HMS Hood was one of the most notable early ships to use this feature, so it would certainly be around).

[JSB]

I decided to have another go (with an AU twist).
What if the US wanted to cheat the WNT slightly, say that one of the dominions split from GB and refused to be counted in the same total, what then would the US be willing to 'help its allies' get a costal ship ?

I give you the Panamanian Canal Gun Boat. (of 1925)


1x3 16inch (16/50 from cancelled BBs)
4 x 3 inch
4 x .5
Very wide, slow and unseaworthy (but does it matter if you don't intend to leave the canal much).

JSB

[acelanceloet]

the problem is that you don't get that turret in that hull. look at the HMS Terror and Erebus, how high on the ship that turret was placed. this was mainly because the barbette underneath it required that height.
http://shipbucket.com/images.php?dir=Re ... Erebus.png
also, could you do me a favor and use the standard template? we have those for a reason.

[JSB]

Ok I will redo it with a standard template.

Does it need to be higher ? cant the ship be deep, its not going to work in shallow water as its going to site in the canal/in each entrance channels ?

[heuhen]

A ship can't just be deeper. the dept of a hull is proportionate to how much a ship weight, so if a ship weight 3000 tons... then it push 3000++ tons of water away.

But on the other hand I was believing this ...topic was about Coastal Battleships and defense ships, and not monitors....

[JSB]

A ship can't just be deeper. the dept of a hull is proportionate to how much a ship weight, so if a ship weight 3000 tons... then it push 3000++ tons of water away.

But on the other hand I was believing this ...topic was about Coastal Battleships and defense ships, and not monitors....

Sorry to derail the CBS thread,

But since in haven't drawn the depth (or said the size of the ship apart from under 10,000t ish) cant I just have a bigger ship (with less % freeboard so more of it is underwater) ?

My ship could be deep (as its only going to operate in deep dredged waters) and have very low freeboard (as its not going out into big seas) and thus have the hull depth to fit a big turret ?

(I do actually agree I should probably change it to more like the rn monitors, but would the above not work ?)

JSB

[heuhen]

you can't increase depth.. just like that. Thus deeper a ship is thus heavier it have to be. If you want to make the ship deep, then you can add ballast... let us say the two lower deck with concrete... oh wait that's where the engine and magazine is going. other problem you get is stability, you'r ship doesn't have any... she is just to small for triple 16" guns, one salvo... The Only Monitor that had big gun was an British one that had an aft mounted 18" single gun... and to target anything you had to move the entire ship to do so... and that Monitor was almost three time as big than you'rs. And it had to operate together with HMS Gorgon (ex Bjorgvin class) due to that ship was the only ship that could fire accurate at that range the 18" could fire!

The only ships that I know of that manage to combine big guns with low free-board is CDS.

and monitor don't need 16" guns when it's task is to just protect one small area.. shore line artillery do that better. an monitor task is to stop destroyers, cruiser and give artillery support that's it.

Now draw an 10000 ton coastal battleship that can travel along an coastline, weather should be an problem to it either. What you do is taking an BB and just shrink it by 200-400% and instead of 4 guns give it 2 fast loading 8-10" guns... done