Atacama-class, Chilean Light Cruiser laid down 1926 (Engine 1943)
Between 1943 and 1944, a refit program for the
Atacama-class cruisers was instituted.
Displacement:
9,165 t light; 9,554 t standard; 10,975 t normal; 12,113 t full load
Dimensions: Length overall / water x beam x draught
556.95 ft / 551.00 ft x 64.00 ft x 22.60 ft (normal load)
169.76 m / 167.94 m x 19.51 m x 6.89 m
Armament:
12 - 5.91" / 150 mm guns (4x3 guns), 102.98lbs / 46.71kg shells, 1926 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, evenly spread, 2 raised mounts - superfiring
8 - 4.33" / 110 mm guns (4x2 guns), 40.61lbs / 18.42kg shells, 1943 Model
Dual purpose guns in deck mounts with hoists
on centreline, all amidships
12 - 1.57" / 40.0 mm guns (6x2 guns), 1.95lbs / 0.88kg shells, 1943 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
16 - 1.10" / 27.9 mm guns (2x8 guns), 0.67lbs / 0.30kg shells, 1943 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 1,595 lbs / 723 kg
Shells per gun, main battery: 180
12 - 21.0" / 533.4 mm above water torpedoes
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 4.33" / 110 mm 350.00 ft / 106.68 m 10.00 ft / 3.05 m
Ends: Unarmoured
Upper: 2.76" / 70 mm 170.00 ft / 51.82 m 5.00 ft / 1.52 m
Main Belt covers 98 % of normal length
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 5.51" / 140 mm 3.94" / 100 mm 3.15" / 80 mm
2nd: 0.79" / 20 mm 0.20" / 5 mm 0.20" / 5 mm
3rd: 0.20" / 5 mm 0.20" / 5 mm -
4th: 0.20" / 5 mm 0.20" / 5 mm -
- Armour deck: 1.97" / 50 mm, Conning tower: 1.57" / 40 mm
Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 93,433 shp / 69,701 Kw = 32.00 kts
Range 12,000nm at 15.00 kts
Bunker at max displacement = 2,559 tons
Complement:
535 - 696
Cost:
£2.854 million / $11.414 million
Distribution of weights at normal displacement:
Armament: 199 tons, 1.8 %
Armour: 2,018 tons, 18.4 %
- Belts: 758 tons, 6.9 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 401 tons, 3.7 %
- Armour Deck: 842 tons, 7.7 %
- Conning Tower: 17 tons, 0.2 %
Machinery: 2,413 tons, 22.0 %
Hull, fittings & equipment: 4,235 tons, 38.6 %
Fuel, ammunition & stores: 1,811 tons, 16.5 %
Miscellaneous weights: 300 tons, 2.7 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
15,149 lbs / 6,871 Kg = 147.1 x 5.9 " / 150 mm shells or 1.9 torpedoes
Stability (Unstable if below 1.00): 1.10
Metacentric height 3.1 ft / 0.9 m
Roll period: 15.4 seconds
Steadiness - As gun platform (Average = 50 %): 64 %
- Recoil effect (Restricted arc if above 1.00): 0.44
Seaboat quality (Average = 1.00): 1.16
Hull form characteristics:
Hull has rise forward of midbreak
Block coefficient: 0.482
Length to Beam Ratio: 8.61 : 1
'Natural speed' for length: 23.47 kts
Power going to wave formation at top speed: 60 %
Trim (Max stability = 0, Max steadiness = 100): 55
Bow angle (Positive = bow angles forward): 12.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 28.00 ft / 8.53 m
- Forecastle (25 %): 27.00 ft / 8.23 m
- Mid (60 %): 26.00 ft / 7.92 m (16.00 ft / 4.88 m aft of break)
- Quarterdeck (18 %): 16.00 ft / 4.88 m
- Stern: 16.00 ft / 4.88 m
- Average freeboard: 22.53 ft / 6.87 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 89.2 %
- Above water (accommodation/working, high = better): 141.4 %
Waterplane Area: 23,118 Square feet or 2,148 Square metres
Displacement factor (Displacement / loading): 126 %
Structure weight / hull surface area: 108 lbs/sq ft or 529 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.92
- Longitudinal: 2.07
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Breakdown of Miscellaneous Weights:
- 75 tons for 3x Coati seaplanes
- 15 tons for catapult and crane
- 120 tons for Electronics Suite
- 50 tons for crew comforts (air conditioning, movie theatre, and ice cream machine)
- 25 tons for electronic fire-control on 150mm, 110mm, and 40mm guns
- 15 tons for extra damage-control gear, pumps, etc
Total weight: 300 tons
Ships in Class:
- CNS
Atacama (refitted 1943-1944)
- CNS
Picunches (refitted 1945-1946)
- CNS
Antofagasta (refitted 1946-1947)
* * * * *
Image by thesmilingassassin and colored by Brockpaine
Atacama-class, Chilean Light Cruiser laid down 1926 (Atlantean design)
Original design of these cruisers prior to refit.
Displacement:
9,747 t light; 10,105 t standard; 10,975 t normal; 11,671 t full load
Dimensions: Length overall / water x beam x draught
556.95 ft / 551.00 ft x 64.00 ft x 22.60 ft (normal load)
169.76 m / 167.94 m x 19.51 m x 6.89 m
Armament:
12 - 5.90" / 150 mm guns (4x3 guns), 102.69lbs / 46.58kg shells, 1926 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, evenly spread, 2 raised mounts - superfiring
8 - 4.33" / 110 mm guns (4x2 guns), 40.59lbs / 18.41kg shells, 1926 Model
Quick firing guns in deck mounts
on side, all aft
12 - 1.46" / 37.0 mm guns (6x2 guns), 1.54lbs / 0.70kg shells, 1926 Model
Anti-aircraft guns in deck mounts
on side, evenly spread
Weight of broadside 1,575 lbs / 715 kg
Shells per gun, main battery: 150
12 - 21.0" / 533.4 mm above water torpedoes
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 4.10" / 104 mm 350.00 ft / 106.68 m 10.00 ft / 3.05 m
Ends: Unarmoured
Upper: 2.76" / 70 mm 170.00 ft / 51.82 m 5.00 ft / 1.52 m
Main Belt covers 98 % of normal length
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 5.50" / 140 mm 3.92" / 100 mm 3.15" / 80 mm
2nd: 1.00" / 25 mm - -
- Armour deck: 1.57" / 40 mm, Conning tower: 1.57" / 40 mm
Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 82,011 shp / 61,180 Kw = 31.00 kts
Range 10,000nm at 12.00 kts
Bunker at max displacement = 1,566 tons
Complement:
535 - 696
Cost:
£3.020 million / $12.079 million
Distribution of weights at normal displacement:
Armament: 197 tons, 1.8 %
Armour: 1,825 tons, 16.6 %
- Belts: 724 tons, 6.6 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 413 tons, 3.8 %
- Armour Deck: 671 tons, 6.1 %
- Conning Tower: 17 tons, 0.2 %
Machinery: 2,625 tons, 23.9 %
Hull, fittings & equipment: 4,950 tons, 45.1 %
Fuel, ammunition & stores: 1,228 tons, 11.2 %
Miscellaneous weights: 150 tons, 1.4 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
14,422 lbs / 6,542 Kg = 140.4 x 5.9 " / 150 mm shells or 1.8 torpedoes
Stability (Unstable if below 1.00): 1.08
Metacentric height 2.9 ft / 0.9 m
Roll period: 15.7 seconds
Steadiness - As gun platform (Average = 50 %): 71 %
- Recoil effect (Restricted arc if above 1.00): 0.45
Seaboat quality (Average = 1.00): 1.26
Hull form characteristics:
Hull has raised forecastle
Block coefficient: 0.482
Length to Beam Ratio: 8.61 : 1
'Natural speed' for length: 23.47 kts
Power going to wave formation at top speed: 58 %
Trim (Max stability = 0, Max steadiness = 100): 56
Bow angle (Positive = bow angles forward): 12.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 28.00 ft / 8.53 m
- Forecastle (25 %): 27.50 ft / 8.38 m (26.00 ft / 7.92 m aft of break)
- Mid (45 %): 26.00 ft / 7.92 m
- Quarterdeck (18 %): 16.00 ft / 4.88 m
- Stern: 16.00 ft / 4.88 m
- Average freeboard: 22.78 ft / 6.94 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 93.5 %
- Above water (accommodation/working, high = better): 143.4 %
Waterplane Area: 23,118 Square feet or 2,148 Square metres
Displacement factor (Displacement / loading): 125 %
Structure weight / hull surface area: 126 lbs/sq ft or 615 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.09
- Longitudinal: 2.48
- Overall: 1.18
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform
Good seaboat, rides out heavy weather easily
Breakdown of Miscellaneous Weights:
N/A
Ships in Class:
-
Atacama (CL-6) - 1926 (Atlantis-built)
-
Picunches (CL-7) - 1927 (Atlantis-built)
-
Antofagasta (CL-9) - 1932 (Atlantis-built)