Re: SDN World 3 Ship Design Thread
Posted: 2010-03-21 03:31pm
This is the tentative design for my next light cruiser. At 10,000 tons standard she may seem a bit bloated for a six-gun cruiser, but there was no other way to combine a 32-knot speed (the same as the previous class) without using a large transom, a 1.2 seakeeping rating, plus the scale of armor protection I wanted. Even then I had to scratch my head to keep it under 10,000 tons for the sake of the build-time threshold.
CL1927, Madagascar Light Cruiser laid down 1926 (Engine 1927)
Displacement:
9,603 t light; 9,999 t standard; 11,353 t normal; 12,435 t full load
Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(575.79 ft / 567.59 ft) x 55.77 ft (Bulges 62.34 ft) x (22.97 / 24.74 ft)
(175.50 m / 173.00 m) x 17.00 m (Bulges 19.00 m) x (7.00 / 7.54 m)
Armament:
6 - 7.87" / 200 mm 50.0 cal guns - 279.99lbs / 127.00kg shells, 140 per gun
Breech loading guns in turret on barbette mounts, 1926 Model
3 x 2-gun mounts on centreline ends, majority forward
1 raised mount - superfiring
7 - 3.94" / 100.0 mm 50.0 cal guns - 30.86lbs / 14.00kg shells, 275 per gun
Dual purpose guns in deck mounts, 1926 Model
6 x Single mounts on sides, aft deck forward
6 raised mounts
1 x Single mount on centreline, aft deck aft
1 raised mount
20 - 0.59" / 15.0 mm 90.0 cal guns - 0.17lbs / 0.08kg shells, 3,000 per gun
Anti-air guns in deck mounts, 1926 Model
8 x Single mounts on centreline, evenly spread
8 raised mounts
6 x Twin mounts on centreline, evenly spread
6 raised mounts
Weight of broadside 1,899 lbs / 862 kg
Main Torpedoes
8 - 21.7" / 550 mm, 24.61 ft / 7.50 m torpedoes - 1.691 t each, 13.530 t total
In 2 sets of deck mounted side rotating tubes
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 5.51" / 140 mm 354.33 ft / 108.00 m 12.04 ft / 3.67 m
Ends: Unarmoured
Main Belt covers 96 % of normal length
Main Belt inclined 5.00 degrees (positive = in)
- Torpedo Bulkhead - Strengthened structural bulkheads:
0.98" / 25 mm 354.33 ft / 108.00 m 19.91 ft / 6.07 m
Beam between torpedo bulkheads 55.77 ft / 17.00 m
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 7.87" / 200 mm 3.74" / 95 mm 5.91" / 150 mm
2nd: 0.98" / 25 mm - -
3rd: 0.39" / 10 mm - -
- Armoured deck - single deck:
For and Aft decks: 2.56" / 65 mm
Forecastle: 0.00" / 0 mm Quarter deck: 1.57" / 40 mm
- Conning towers: Forward 5.91" / 150 mm, Aft 0.00" / 0 mm
Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 86,000 shp / 64,156 Kw = 32.00 kts
Range 9,180nm at 15.00 kts
Bunker at max displacement = 2,436 tons
Complement:
549 - 714
Cost:
£3.078 million / $12.311 million
Distribution of weights at normal displacement:
Armament: 561 tons, 4.9 %
- Guns: 534 tons, 4.7 %
- Weapons: 27 tons, 0.2 %
Armour: 2,640 tons, 23.3 %
- Belts: 970 tons, 8.5 %
- Torpedo bulkhead: 257 tons, 2.3 %
- Armament: 475 tons, 4.2 %
- Armour Deck: 874 tons, 7.7 %
- Conning Tower: 64 tons, 0.6 %
Machinery: 2,715 tons, 23.9 %
Hull, fittings & equipment: 3,623 tons, 31.9 %
Fuel, ammunition & stores: 1,750 tons, 15.4 %
Miscellaneous weights: 64 tons, 0.6 %
- On freeboard deck: 64 tons
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
13,613 lbs / 6,175 Kg = 55.8 x 7.9 " / 200 mm shells or 1.6 torpedoes
Stability (Unstable if below 1.00): 1.15
Metacentric height 2.7 ft / 0.8 m
Roll period: 15.9 seconds
Steadiness - As gun platform (Average = 50 %): 60 %
- Recoil effect (Restricted arc if above 1.00): 0.45
Seaboat quality (Average = 1.00): 1.20
Hull form characteristics:
Hull has a flush deck,
a normal bow and small transom stern
Block coefficient (normal/deep): 0.489 / 0.497
Length to Beam Ratio: 9.11 : 1
'Natural speed' for length: 25.69 kts
Power going to wave formation at top speed: 58 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 12.90 degrees
Stern overhang: 1.64 ft / 0.50 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 22.10 %, 28.67 ft / 8.74 m, 21.49 ft / 6.55 m
- Forward deck: 25.00 %, 21.49 ft / 6.55 m, 19.69 ft / 6.00 m
- Aft deck: 37.40 %, 19.69 ft / 6.00 m, 19.69 ft / 6.00 m
- Quarter deck: 15.50 %, 19.69 ft / 6.00 m, 19.69 ft / 6.00 m
- Average freeboard: 20.94 ft / 6.38 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 92.5 %
- Above water (accommodation/working, high = better): 144.2 %
Waterplane Area: 21,380 Square feet or 1,986 Square metres
Displacement factor (Displacement / loading): 116 %
Structure weight / hull surface area: 108 lbs/sq ft or 525 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.93
- Longitudinal: 1.87
- Overall: 1.00
Adequate machinery, storage, compartmentation space
Excellent accommodation and workspace room
Good seaboat, rides out heavy weather easily
50 tons for aircraft carried
13.5 tons for torpedoes