WesWorld

I hope this is OK to post here, I've been playing about with spring sharp to try and come up with a small AA cruiser/Flotilla leader type.

She has quite a heavy 40mm Fit, which may be unrealistic but it's balanced by a light torpedo fit of only 4 tubes in twin mounts.

I'm not quite sure about the depth and size of the Belt armour, or indeed weather it's needed.

All critiques are welcome as i's still learning to use SS2 so all advice is welcome.


F Class Light AA, UK CLAA laid down 1934

Displacement:
3,820 t light; 3,969 t standard; 4,337 t normal; 4,632 t full load

Dimensions: Length overall / water x beam x draught
427.43 ft / 411.00 ft x 40.00 ft x 19.00 ft (normal load)
130.28 m / 125.27 m x 12.19 m x 5.79 m

Armament:
8 - 4.70" / 119 mm guns (4x2 guns), 51.91lbs / 23.55kg shells, 1934 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, evenly spread, 2 raised mounts - superfiring
4 - 1.57" / 40.0 mm guns (2x2 guns), 1.95lbs / 0.89kg shells, 1934 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
4 - 1.57" / 40.0 mm guns (2x2 guns), 1.95lbs / 0.89kg shells, 1934 Model
Anti-aircraft guns in deck mounts
on centreline ends, evenly spread, all raised mounts
4 - 0.79" / 20.0 mm guns in single mounts, 0.24lbs / 0.11kg shells, 1934 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
4 - 0.79" / 20.0 mm guns in single mounts, 0.24lbs / 0.11kg shells, 1934 Model
Anti-aircraft guns in deck mounts
on centreline, evenly spread
Weight of broadside 433 lbs / 196 kg
Shells per gun, main battery: 250
4 - 21.0" / 533.4 mm above water torpedoes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 1.50" / 38 mm 340.00 ft / 103.63 m 11.00 ft / 3.35 m
Ends: Unarmoured
Main Belt covers 127 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2.00" / 51 mm 0.50" / 13 mm 2.00" / 51 mm

- Armour deck: 2.00" / 51 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 45,084 shp / 33,633 Kw = 30.00 kts
Range 8,000nm at 12.00 kts
Bunker at max displacement = 663 tons

Complement:
266 - 347

Cost:
£1.771 million / $7.084 million

Distribution of weights at normal displacement:
Armament: 54 tons, 1.2 %
Armour: 652 tons, 15.0 %
- Belts: 225 tons, 5.2 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 27 tons, 0.6 %
- Armour Deck: 400 tons, 9.2 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 1,297 tons, 29.9 %
Hull, fittings & equipment: 1,567 tons, 36.1 %
Fuel, ammunition & stores: 517 tons, 11.9 %
Miscellaneous weights: 250 tons, 5.8 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
3,719 lbs / 1,687 Kg = 71.6 x 4.7 " / 119 mm shells or 0.8 torpedoes
Stability (Unstable if below 1.00): 1.01
Metacentric height 1.3 ft / 0.4 m
Roll period: 14.8 seconds
Steadiness - As gun platform (Average = 50 %): 76 %
- Recoil effect (Restricted arc if above 1.00): 0.60
Seaboat quality (Average = 1.00): 1.26

Hull form characteristics:
Hull has rise forward of midbreak
Block coefficient: 0.486
Length to Beam Ratio: 10.28 : 1
'Natural speed' for length: 20.27 kts
Power going to wave formation at top speed: 61 %
Trim (Max stability = 0, Max steadiness = 100): 60
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 10.00 ft / 3.05 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 24.00 ft / 7.32 m
- Forecastle (18 %): 18.00 ft / 5.49 m
- Mid (60 %): 18.00 ft / 5.49 m (15.00 ft / 4.57 m aft of break)
- Quarterdeck (18 %): 15.00 ft / 4.57 m
- Stern: 15.00 ft / 4.57 m
- Average freeboard: 17.22 ft / 5.25 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 113.7 %
- Above water (accommodation/working, high = better): 109.3 %
Waterplane Area: 10,816 Square feet or 1,005 Square metres
Displacement factor (Displacement / loading): 110 %
Structure weight / hull surface area: 70 lbs/sq ft or 340 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.89
- Longitudinal: 2.93
- Overall: 1.00
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is adequate
Ship has slow, easy roll, a good, steady gun platform
Good seaboat, rides out heavy weather easily

250T Misc Weight - Reserved for 2 AA Directors and Radar fit

Not a bad design for an early effort. There are several areas in which it might be improved.

1. Rather than having the 20mm LAA in single mounts, I would considering mounting the in pairs along the side, rather than some on the side and some on the centerline.

2. The stability of the ship is rather low; while 1.01 is in theory an acceptable value, any damage to the ship would require immediate counter flooding; if you were to improve the design, I would strive for more stability; consider adjusting the trim to balance the stability versus sea-keeping.

3. Overall, armor is on the light side of things; this is likely a factor of the overall size of the design and its small tonnage.

4. For a cruiser, the speed is in the low end of the spectrum; not unacceptable, but slower than most contemporaries, and certainly slower than destroyers were it to operate as a flotilla leader.

To address some of these issues, I would first suggest building the design with a transom stern; this has the effect of allowing you to take advantage of waterflow to achieve additional speed at no cost of engine power.

Consolidating the 20mm AA armament into twin mounts, and perhaps the 40mm AA armament into quad mounts, would also economize on tonnage and perhaps allow light armor for the LAA mounts. As it stands now they are all open.

I am of two minds about the usefulness of an amored deck on so small a design; the older hands here can give you better guidance.

To add to Bruce's comments about armor: I personally think that the belt is to thin to stop most rounds and should be omitted. It would then look like more of an late 1800's/early 1900's PC in terms of its armor layout, which on this tonnage may be a better way to go about things.

Other comments: I would remove the torpedo tubes as two abeam is not enough to warent there inclusion in my mind. and add on some more speed, which with a transom stern should be more then possible. I would also consider lowering the Stem height, as the 18ft to 24ft difference would make getting low-angle shots over the bow harder without elevating the turret. I would also increase the rounds for the main battery to at least 400. Other then those things, I like the design. Great first go.

Interesting design. It appears you've avoided most of the more serious pitfalls of first-time Springsharp users, so congratulations.

I would join the crowd of people concerned about her armour. The side belts are frankly insufficient to stop much beside perhaps 3" rounds at most battle ranges. At the same time, the 2" thick deck is quite thick by comparison, but not thick enough to stop an aerial bomb. Frankly, I'd make the ship unarmoured completely, aside from the armament and conn. Use the weight to improve the speed, which is somewhat deficient (and as Bruce says, the transom stern will help).

My opinion, which Springsharp itself will not reveal, is that four shafts on a ship of this beam is rather too many, as it would require a tight machinery layout in the engine rooms. The only reason I'd consider four shafts on a ship this size is if the manufacturer was unable to build a shaft capable of higher shaft horsepowers; but that'd not be too likely, so two shafts is probably better.

I'm not so sure on the armour myself. It'll probably still be useful if the ship is used in cruiser roles. The 2" armour deck should be good against most HE bombs and light AP, this is only the mid 30s.

Overall, it reminds me of the C and D Class cruiser rebuilds from the RN in the 1930s. Very similar size and characteristics. I'm just not sure that I'd build such a ship in 1934. I think increasing speed to 32kts+ would increase it's value quite a bit.

Quoted

Originally posted by Red Admiral
I'm not so sure on the armour myself. It'll probably still be useful if the ship is used in cruiser roles. The 2" armour deck should be good against most HE bombs and light AP, this is only the mid 30s.

Ah, true; I didn't take notice of the date.

Regarding armour: mm, yes, it might be useful in that event, in which case I'd suggest upsizing the vessel to do the job appropriately, or arranging the armour in a box around machinery or magazines, as the British did in other period cruisers.

Thanks for all the feed back.

Red Admiral was almost correct, the plan was to build a cheap fast-ish convoy or fleet AA escort that is almost disposable, she's really nothing more than a pumped up destroyer with much improved HA FCS, hopefully she could be built to commercial scantlings to save costs.

Which is part of the thinking behind the high steadiness and lowish stability, hopefully giving a decent gun platform. Following advice I have increased the stability.

The box armour scheme is one I would like to go for, is there a way to sim it in SS2?

She has been reduced to 2 shafts and now only has splinter protection on the belt and deck.

Quoted

F Class Light AA, UK CLAA laid down 1934

Displacement:
3,445 t light; 3,623 t standard; 3,959 t normal; 4,228 t full load

Dimensions: Length overall / water x beam x draught
415.89 ft / 400.00 ft x 37.50 ft (Bulges 37.75 ft) x 19.00 ft (normal load)
126.76 m / 121.92 m x 11.43 m (Bulges 11.51 m) x 5.79 m

Armament:
8 - 4.70" / 119 mm guns (4x2 guns), 51.91lbs / 23.55kg shells, 1934 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, evenly spread, 2 raised mounts - superfiring
4 - 1.57" / 40.0 mm guns (2x2 guns), 1.95lbs / 0.88kg shells, 1934 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
4 - 1.57" / 40.0 mm guns (2x2 guns), 1.95lbs / 0.88kg shells, 1934 Model
Anti-aircraft guns in deck mounts
on centreline ends, evenly spread, all raised mounts
8 - 0.79" / 20.0 mm guns (4x2 guns), 0.24lbs / 0.11kg shells, 1934 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
4 - 0.00" / 0.0 mm guns in single mounts, 0.00lbs / 0.00kg shells, 8 Model
Muzzle loading guns in deck mounts
on centreline, evenly spread
Weight of broadside 433 lbs / 196 kg
Shells per gun, main battery: 400
6 - 21.0" / 533.4 mm above water torpedoes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 1.00" / 25 mm 343.00 ft / 104.55 m 11.00 ft / 3.35 m
Ends: Unarmoured
Main Belt covers 132 % of normal length
Main belt does not fully cover magazines and engineering spaces

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2.00" / 51 mm 0.50" / 13 mm 2.00" / 51 mm

- Armour deck: 0.50" / 13 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 48,008 shp / 35,814 Kw = 32.00 kts
Range 8,000nm at 12.00 kts
Bunker at max displacement = 605 tons

Complement:
249 - 324

Cost:
£1.764 million / $7.057 million

Distribution of weights at normal displacement:
Armament: 54 tons, 1.4 %
Armour: 271 tons, 6.9 %
- Belts: 150 tons, 3.8 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 27 tons, 0.7 %
- Armour Deck: 95 tons, 2.4 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 1,381 tons, 34.9 %
Hull, fittings & equipment: 1,488 tons, 37.6 %
Fuel, ammunition & stores: 514 tons, 13.0 %
Miscellaneous weights: 250 tons, 6.3 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
2,674 lbs / 1,213 Kg = 51.5 x 4.7 " / 119 mm shells or 0.6 torpedoes
Stability (Unstable if below 1.00): 1.10
Metacentric height 1.4 ft / 0.4 m
Roll period: 13.5 seconds
Steadiness - As gun platform (Average = 50 %): 51 %
- Recoil effect (Restricted arc if above 1.00): 0.56
Seaboat quality (Average = 1.00): 1.11

Hull form characteristics:
Hull has rise forward of midbreak
and transom stern
Block coefficient: 0.483
Length to Beam Ratio: 10.60 : 1
'Natural speed' for length: 22.77 kts
Power going to wave formation at top speed: 65 %
Trim (Max stability = 0, Max steadiness = 100): 46
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 10.00 ft / 3.05 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 22.00 ft / 6.71 m
- Forecastle (18 %): 18.00 ft / 5.49 m
- Mid (60 %): 18.00 ft / 5.49 m (15.00 ft / 4.57 m aft of break)
- Quarterdeck (18 %): 15.00 ft / 4.57 m
- Stern: 15.00 ft / 4.57 m
- Average freeboard: 17.08 ft / 5.21 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 132.1 %
- Above water (accommodation/working, high = better): 96.2 %
Waterplane Area: 10,231 Square feet or 951 Square metres
Displacement factor (Displacement / loading): 107 %
Structure weight / hull surface area: 68 lbs/sq ft or 331 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.87
- Longitudinal: 3.35
- Overall: 1.00
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is adequate

250T Misc Weight - Reserved for 2 AA Directors and Radar fit