WesWorld

Based on my previous large destroyer design but now beefed up to 4500 t standard. The 150mm guns should have some limited capabilities aginst aircrafts. Perhaps not the best design ever, but me still want to know what people think.


Enter ship name, Siam Scout Cruiser laid down 1938

Displacement:
4,291 t light; 4,500 t standard; 5,057 t normal; 5,502 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(555.83 ft / 541.34 ft) x 49.21 ft x (14.76 / 15.65 ft)
(169.42 m / 165.00 m) x 15.00 m x (4.50 / 4.77 m)

Armament:
6 - 5.91" / 150 mm 60.0 cal guns - 110.23lbs / 50.00kg shells, 200 per gun
Dual purpose guns in deck and hoist mounts, 1938 Model
2 x Twin mounts on centreline, forward deck forward
1 raised mount - superfiring
1 x Twin mount on centreline, aft deck aft
8 - 2.17" / 55.0 mm 55.0 cal guns - 5.51lbs / 2.50kg shells, 1,200 per gun
Anti-air guns in deck mounts, 1938 Model
4 x Twin mounts on centreline, evenly spread
4 raised mounts
8 - 0.98" / 25.0 mm 75.0 cal guns - 0.55lbs / 0.25kg shells, 2,000 per gun
Anti-air guns in deck mounts, 1938 Model
8 x Single mounts on sides, evenly spread
4 raised mounts
Weight of broadside 710 lbs / 322 kg
Main Torpedoes
8 - 23.6" / 600 mm, 29.53 ft / 9.00 m torpedoes - 2.402 t each, 19.214 t total
In 2 sets of deck mounted centre rotating tubes
Main DC/AS Mortars
40 - 440.92 lbs / 200.00 kg Depth Charges - 7.874 t total
in Stern depth charge racks

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 0.79" / 20 mm 351.87 ft / 107.25 m 8.20 ft / 2.50 m
Ends: Unarmoured
Main Belt covers 100% of normal length
Main belt does not fully cover magazines and engineering spaces

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.97" / 50 mm 0.79" / 20 mm 0.79" / 20 mm
2nd: 0.79" / 20 mm - -
3rd: 0.39" / 10 mm - -

- Conning towers: Forward 1.97" / 50 mm, Aft 0.79" / 20 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 77,053 shp / 57,482 Kw = 36.00 kts
Range 3,535nm at 20.00 kts
Bunker at max displacement = 1,003 tons

Complement:
299 - 389

Cost:
£3.012 million / $12.050 million

Distribution of weights at normal displacement:
Armament: 264 tons, 5.2%
- Guns: 216 tons, 4.3%
- Weapons: 48 tons, 1.0%
Armour: 138 tons, 2.7%
- Belts: 92 tons, 1.8%
- Armament: 28 tons, 0.6%
- Conning Towers: 17 tons, 0.3%
Machinery: 2,110 tons, 41.7%
Hull, fittings & equipment: 1,739 tons, 34.4%
Fuel, ammunition & stores: 766 tons, 15.1%
Miscellaneous weights: 40 tons, 0.8%
- On freeboard deck: 20 tons
- Above deck: 20 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
2,462 lbs / 1,117 Kg = 23.9 x 5.9 " / 150 mm shells or 0.3 torpedoes
Stability (Unstable if below 1.00): 1.23
Metacentric height 2.5 ft / 0.8 m
Roll period: 13.0 seconds
Steadiness - As gun platform (Average = 50 %): 57 %
- Recoil effect (Restricted arc if above 1.00): 0.35
Seaboat quality (Average = 1.00): 1.03

Hull form characteristics:
Hull has a flush deck,
a normal bow and large transom stern
Block coefficient (normal/deep): 0.450 / 0.462
Length to Beam Ratio: 11.00 : 1
'Natural speed' for length: 26.52 kts
Power going to wave formation at top speed: 61 %
Trim (Max stability = 0, Max steadiness = 100): 56
Bow angle (Positive = bow angles forward): 25.00 degrees
Stern overhang: 1.64 ft / 0.50 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 20.00%, 27.56 ft / 8.40 m, 21.00 ft / 6.40 m
- Forward deck: 20.00%, 21.00 ft / 6.40 m, 16.40 ft / 5.00 m
- Aft deck: 45.00%, 16.40 ft / 5.00 m, 16.40 ft / 5.00 m
- Quarter deck: 15.00%, 16.40 ft / 5.00 m, 16.40 ft / 5.00 m
- Average freeboard: 18.31 ft / 5.58 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 151.8%
- Above water (accommodation/working, high = better): 159.2%
Waterplane Area: 17,652 Square feet or 1,640 Square metres
Displacement factor (Displacement / loading): 96%
Structure weight / hull surface area: 63 lbs/sq ft or 309 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.71
- Longitudinal: 1.20
- Overall: 0.75
Caution: Hull subject to strain in open-sea
Cramped machinery, storage, compartmentation space
Excellent accommodation and workspace room

Interesting aggressive design.

I'm not a fan of twin mount & hoist 150mm guns. The weight is fairly hefty for that structure. The Omahas had such a mount and it was considered underarmored and slow. I'd rather see 5x 1. My bias.

I'm not sure at what point beam becomes "to much" for centerline torpedo mountings to be functional, but I suspect that might be a problem.

The belt is of debatable use. Likely arranged as WL - 2.5m, it has some utility since your engines likely extend above WL. 20mm will stop strafing and shell splinters from smaller shells, though it won't stop a common or possibly HE round from penetrating.
For my taste, I'd like to see it cover the "magazines and engineering spaces", which will likely take a belt over most of the hull.

However, the lack of an armored deck robs the belt of most of it's utility. Shells exploding in the upper reaches of the ship can shower splinters into critical areas, as can strafing aircraft. The OTL Fletcher had a 0.75" belt and 0.5" deck.

I also don't see why the con is more heavily armored than the magazines and boilers. The latter explode. The former, you need the Aux Con.

Good points, KK.

I´d like to add the high l:b ratio again which is a risk.

Regarding mount&hoist - IJN Yubari also had enclosed deckmounts with hoist but no barbets to speak of. Same for the Dutch Tromp.

Her armor suit really makes no sense at all and hardly protects anything. You can´t outrun a shell so at least magazins and machinery should have some protection when you spend 4500 tons which is quite a lot for a small country.

Btw, what is the mission profile for that ship (or any of the others recently posted)? Coming up with weird designs is easy. Coming up with a reasonable doctrine and strategy for a given country and environment is more difficult and to design ships that fit into budget and answer such doctrine and strategy is the task to master.

Looking at it, I suspect you can get the same main armament on your previous hull (judging by the Peruvian Indepencia class). 60 caliber 15cms might be a bit much for the mount & hoist mounting, but 53 and 48 caliber guns were fine (see Omaha, Zerstorer 1936a (mob), etc). The 20mm belt, as noted, is pretty marginal, being useful against smaller splinters and very small caliber guns but pointless against larger weapons.

A slightly revised version in response to posts. Cut down on range for slightly better protection. I wasn't able to fit the 150mm guns I have here for my previous design. I'll have to cut down to something like 4 guns or something else has to go away.



Enter ship name, Siam Scout Cruiser laid down 1938

Displacement:
4,309 t light; 4,500 t standard; 4,995 t normal; 5,390 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(555.83 ft / 541.34 ft) x 49.21 ft x (16.40 / 17.22 ft)
(169.42 m / 165.00 m) x 15.00 m x (5.00 / 5.25 m)

Armament:
5 - 5.91" / 150 mm 60.0 cal guns - 110.23lbs / 50.00kg shells, 200 per gun
Dual purpose guns in deck and hoist mounts, 1938 Model
2 x Single mounts on centreline, forward deck forward
1 raised mount - superfiring
3 x Single mounts on centreline, aft evenly spread
2 raised mounts
8 - 2.17" / 55.0 mm 55.0 cal guns - 5.51lbs / 2.50kg shells, 1,000 per gun
Anti-air guns in deck mounts, 1938 Model
4 x Twin mounts on centreline, evenly spread
4 raised mounts
8 - 0.98" / 25.0 mm 75.0 cal guns - 0.55lbs / 0.25kg shells, 2,000 per gun
Anti-air guns in deck mounts, 1938 Model
4 x Twin mounts on sides, evenly spread
4 raised mounts
Weight of broadside 600 lbs / 272 kg
Main Torpedoes
8 - 23.6" / 600 mm, 29.53 ft / 9.00 m torpedoes - 2.402 t each, 19.214 t total
In 2 sets of deck mounted centre rotating tubes
Main DC/AS Mortars
40 - 440.92 lbs / 200.00 kg Depth Charges - 7.874 t total
in Stern depth charge racks

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 0.79" / 20 mm 512.80 ft / 156.30 m 8.20 ft / 2.50 m
Ends: Unarmoured
Main Belt covers 146% of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.97" / 50 mm 0.79" / 20 mm 0.79" / 20 mm
2nd: 0.79" / 20 mm - -
3rd: 0.39" / 10 mm - -

- Armoured deck - single deck:
For and Aft decks: 0.49" / 13 mm

- Conning towers: Forward 1.97" / 50 mm, Aft 0.79" / 20 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 74,043 shp / 55,236 Kw = 36.00 kts
Range 3,170nm at 20.00 kts
Bunker at max displacement = 891 tons

Complement:
296 - 386

Cost:
£2.871 million / $11.483 million

Distribution of weights at normal displacement:
Armament: 272 tons, 5.5%
- Guns: 224 tons, 4.5%
- Weapons: 48 tons, 1.0%
Armour: 311 tons, 6.2%
- Belts: 127 tons, 2.5%
- Armament: 40 tons, 0.8%
- Armour Deck: 127 tons, 2.5%
- Conning Towers: 17 tons, 0.3%
Machinery: 2,027 tons, 40.6%
Hull, fittings & equipment: 1,658 tons, 33.2%
Fuel, ammunition & stores: 685 tons, 13.7%
Miscellaneous weights: 40 tons, 0.8%
- On freeboard deck: 20 tons
- Above deck: 20 tons

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
2,565 lbs / 1,164 Kg = 24.9 x 5.9 " / 150 mm shells or 0.4 torpedoes
Stability (Unstable if below 1.00): 1.24
Metacentric height 2.5 ft / 0.8 m
Roll period: 13.0 seconds
Steadiness - As gun platform (Average = 50 %): 54 %
- Recoil effect (Restricted arc if above 1.00): 0.31
Seaboat quality (Average = 1.00): 1.07

Hull form characteristics:
Hull has a flush deck,
a normal bow and large transom stern
Block coefficient (normal/deep): 0.400 / 0.411
Length to Beam Ratio: 11.00 : 1
'Natural speed' for length: 26.70 kts
Power going to wave formation at top speed: 59 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 25.00 degrees
Stern overhang: 1.64 ft / 0.50 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 20.00%, 27.56 ft / 8.40 m, 21.00 ft / 6.40 m
- Forward deck: 20.00%, 21.00 ft / 6.40 m, 15.75 ft / 4.80 m
- Aft deck: 45.00%, 15.75 ft / 4.80 m, 15.75 ft / 4.80 m
- Quarter deck: 15.00%, 15.75 ft / 4.80 m, 15.75 ft / 4.80 m
- Average freeboard: 17.85 ft / 5.44 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 145.7%
- Above water (accommodation/working, high = better): 148.8%
Waterplane Area: 17,019 Square feet or 1,581 Square metres
Displacement factor (Displacement / loading): 98%
Structure weight / hull surface area: 63 lbs/sq ft or 307 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.71
- Longitudinal: 1.24
- Overall: 0.75
Caution: Hull subject to strain in open-sea
Cramped machinery, storage, compartmentation space
Excellent accommodation and workspace room

Quoted

Btw, what is the mission profile for that ship (or any of the others recently posted)? Coming up with weird designs is easy. Coming up with a reasonable doctrine and strategy for a given country and environment is more difficult and to design ships that fit into budget and answer such doctrine and strategy is the task to master.

Siam has plenty of older warships that are slow and mainly used for secondary roles and coastal defense. Some form of naval force that can strike out against the enemy may be desired. Since Siam is a small nation, her navy cannot be expected to outfight a greater force possessed by other nations, hence high speed is taken into high consideration to outrun any potential adversary. These newly designed ships are mainly used to make hit and run attacks on the enemy.

The armor protection is meant for protection against splinters and lighter shells only.

Quoted

Originally posted by gaiasabre11
The armor protection is meant for protection against splinters and lighter shells only.

20mm hardly serves that purpose. Light splinters with little enegery, yes. Standard rifle ammunition of 12,7mm and less, yes. Everything above - heavily depends on angle of impact and the actual size of the projectile and the energy it carries.

Quoted

Originally posted by HoOmAn

20mm hardly serves that purpose. Light splinters with little enegery, yes. Standard rifle ammunition of 12,7mm and less, yes. Everything above - heavily depends on angle of impact and the actual size of the projectile and the energy it carries.

So the belt armor should at least be inclined?

btw, I found the armor penetration table for 40mm bofors:

Armor Penetration with 1.960 lbs. (0.889 kg) AP Shell
Estimated for "Class B" Homogeneous Armor
.
Range
"Class B" Armor
0 yards (0 m)
2.70" (69 mm)
2,000 yards (1,829 m)
1.20" (30 mm)
4,000 yards (3,658 m)
0.60" (15 mm)
6,000 yards (5,486 m)
0.45" (11 mm)
Note: This data is from "Battleships: United States Battleships 1935-1992" and is based upon the USN Empirical Armor Penetration formula.


It seems that 20mm is marginally enough to me...

For the roles you've posited, I'd go with your heavy destroyer or a version of that design with the 15cm guns (though possibly somewhat shorter barrels, 60 caliber guns might be a bit much for the mount and hoist and the lightweight hull). This vessel doesn't add enough capability to be worthwhile, IMO.

Quoted

Originally posted by Hrolf Hakonson
For the roles you've posited, I'd go with your heavy destroyer or a version of that design with the 15cm guns (though possibly somewhat shorter barrels, 60 caliber guns might be a bit much for the mount and hoist and the lightweight hull). This vessel doesn't add enough capability to be worthwhile, IMO.

Yeah, probably. This design mainly allows 1~2 more 150mm guns and better protection scheme.

Currently thinking about a shorter main gun of 150mm/55 or 150mm/50, but still want to stick to the 150mm/60 if possible.

edit: I was wrong, I can fit 5 150mms on my previous design.