Philadelphia class light cruiser - as constructed in 1924

Ships in class:

- Philadelphia
- Scranton
- Clarion
- Wilkes-Barre
- Reading
- Flemington
- Wayne
- Hanover
- Perkasie
- Easton
- Harrisburg - Converted into subclass
- Wildwood - Converted into subclass

SpringSharp report, made by

Keisser
********************************************************

USS Philadelphia, USA cruiser laid down 1924

Displacement:

5 976 t light; 6 159 t standard; 6 693 t normal; 7 120 t full load

Dimensions: Length (overall / waterline) x beam x draught (normal/deep)

(500,06 ft / 492,00 ft) x 52,00 ft x (21,00 / 21,93 ft)

(152,42 m / 149,96 m) x 15,85 m x (6,40 / 6,68 m)

Armament:

8 - 6,00" / 152 mm 45,0 cal guns - 108,92lbs / 49,41kg shells, 100 per gun

Dual purpose guns in turret on barbette mounts, 1924 Model

2 x Twin mounts on centreline, forward deck forward

1 raised mount - superfiring

2 x Twin mounts on centreline, aft deck aft

1 raised mount aft - superfiring

6 - 1,10" / 27,9 mm 40,0 cal guns - 0,64lbs / 0,29kg shells, 500 per gun

Anti-air guns in deck mounts, 1924 Model

6 x Single mounts on side ends, majority aft

2 raised mounts - superfiring

Weight of broadside 875 lbs / 397 kg

Main Torpedoes

8 - 21,0" / 533 mm, 30,00 ft / 9,14 m torpedoes - 1,910 t each, 15,283 t total

In 2 sets of deck mounted side rotating tubes

Armour:

- Belts: Width (max) Length (avg) Height (avg)

Main: 2,99" / 76 mm 328,08 ft / 100,00 m 6,56 ft / 2,00 m

Ends: Unarmoured

Main Belt covers 103% of normal length

Main belt does not fully cover magazines and engineering spaces

- Torpedo Bulkhead - Strengthened structural bulkheads:

2,01" / 51 mm 328,08 ft / 100,00 m 6,56 ft / 2,00 m

Beam between torpedo bulkheads 45,93 ft / 14,00 m

- Hull void:

2,99" / 76 mm 175,52 ft / 53,50 m 11,48 ft / 3,50 m

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)

Main: 3,98" / 101 mm 4,00" / 102 mm 3,00" / 76 mm

- Armoured deck - multiple decks:

For and Aft decks: 1,42" / 36 mm

Forecastle: 1,42" / 36 mm Quarter deck: 1,42" / 36 mm

- Conning towers: Forward 10,00" / 254 mm, Aft 10,00" / 254 mm

Machinery:

Oil fired boilers, steam turbines,

Geared drive, 4 shafts, 61 223 shp / 45 672 Kw = 31,00 kts

Range 8 000nm at 12,00 kts

Bunker at max displacement = 960 tons

Complement:

369 - 480

Cost:

£1,774 million / $7,098 million

Distribution of weights at normal displacement:

Armament: 243 tons, 3,6%

- Guns: 213 tons, 3,2%

- Weapons: 31 tons, 0,5%

Armour: 1 423 tons, 21,3%

- Belts: 264 tons, 3,9%

- Torpedo bulkhead: 160 tons, 2,4%

- Void: 223 tons, 2,8%

- Armament: 197 tons, 2,9%

- Armour Deck: 427 tons, 6,4%

- Conning Towers: 153 tons, 2,3%

Machinery: 2 017 tons, 30,1%

Hull, fittings & equipment: 2 293 tons, 34,3%

Fuel, ammunition & stores: 717 tons, 10,7%

Miscellaneous weights: 0 tons, 0,0%

Overall survivability and seakeeping ability:

Survivability (Non-critical penetrating hits needed to sink ship):

5 630 lbs / 2 554 Kg = 52,1 x 6,0 " / 152 mm shells or 0,8 torpedoes

Stability (Unstable if below 1.00): 1,00

Metacentric height 1,9 ft / 0,6 m

Roll period: 15,9 seconds

Steadiness - As gun platform (Average = 50 %): 55 %

- Recoil effect (Restricted arc if above 1.00): 0,47

Seaboat quality (Average = 1.00): 0,87

Hull form characteristics:

Hull has raised forecastle, rise aft of midbreak, low quarterdeck ,

a normal bow and a cruiser stern

Block coefficient (normal/deep): 0,436 / 0,444

Length to Beam Ratio: 9,46 : 1

'Natural speed' for length: 22,18 kts

Power going to wave formation at top speed: 58 %

Trim (Max stability = 0, Max steadiness = 100): 63

Bow angle (Positive = bow angles forward): 21,00 degrees

Stern overhang: 0,00 ft / 0,00 m

Freeboard (% = length of deck as a percentage of waterline length):

Fore end, Aft end

- Forecastle: 33,00%, 21,00 ft / 6,40 m, 14,50 ft / 4,42 m

- Forward deck: 0,00%, 0,00 ft / 0,00 m, 0,00 ft / 0,00 m

- Aft deck: 67,00%, 14,50 ft / 4,42 m, 14,50 ft / 4,42 m

- Quarter deck: 0,00%, 0,00 ft / 0,00 m, 0,00 ft / 0,00 m

- Average freeboard: 15,36 ft / 4,68 m

Ship tends to be wet forward

Ship space, strength and comments:

Space - Hull below water (magazines/engines, low = better): 123,5%

- Above water (accommodation/working, high = better): 114,1%

Waterplane Area: 16 139 Square feet or 1 499 Square metres

Displacement factor (Displacement / loading): 107%

Structure weight / hull surface area: 96 lbs/sq ft or 468 Kg/sq metre

Hull strength (Relative):

- Cross-sectional: 0,96

- Longitudinal: 1,46

- Overall: 1,00

Cramped machinery, storage, compartmentation space

Adequate accommodation and workspace room

Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

1941

1942