GB/CL/1921, Great Britain Light Cruiser laid down 1921
Displacement:
5,674 t light; 5,901 t standard; 6,142 t normal; 6,335 t full load
Dimensions: Length overall / water x beam x draught
517.87 ft / 517.00 ft x 44.00 ft x 18.00 ft (normal load)
157.85 m / 157.58 m x 13.41 m x 5.49 m
Armament:
9 - 5.50" / 140 mm guns (3x3 guns), 83.19lbs / 37.73kg shells, 1921 Model
Quick firing guns in turrets (on barbettes)
on centreline ends, majority forward, all raised mounts - superfiring
8 - 4.70" / 119 mm guns in single mounts, 51.91lbs / 23.55kg shells, 1921 Model
Dual purpose guns in deck mounts with hoists
on side, evenly spread, all raised mounts
Weight of broadside 1,164 lbs / 528 kg
Shells per gun, main battery: 150
6 - 21.0" / 533.4 mm above water torpedoes
Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2.00" / 51 mm 2.00" / 51 mm 2.00" / 51 mm
- Armour deck: 2.00" / 51 mm, Conning tower: 2.00" / 51 mm
Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 64,908 shp / 48,421 Kw = 33.00 kts
Range 3,500nm at 12.00 kts
Bunker at max displacement = 434 tons
Complement:
346 - 450
Cost:
£1.613 million / $6.452 million
Distribution of weights at normal displacement:
Armament: 145 tons, 2.4 %
Armour: 765 tons, 12.5 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 154 tons, 2.5 %
- Armour Deck: 597 tons, 9.7 %
- Conning Tower: 14 tons, 0.2 %
Machinery: 2,235 tons, 36.4 %
Hull, fittings & equipment: 2,528 tons, 41.2 %
Fuel, ammunition & stores: 468 tons, 7.6 %
Miscellaneous weights: 0 tons, 0.0 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
3,663 lbs / 1,662 Kg = 44.0 x 5.5 " / 140 mm shells or 0.7 torpedoes
Stability (Unstable if below 1.00): 1.08
Metacentric height 1.7 ft / 0.5 m
Roll period: 14.2 seconds
Steadiness - As gun platform (Average = 50 %): 53 %
- Recoil effect (Restricted arc if above 1.00): 0.86
Seaboat quality (Average = 1.00): 1.06
Hull form characteristics:
Hull has rise forward of midbreak
and transom stern
Block coefficient: 0.525
Length to Beam Ratio: 11.75 : 1
'Natural speed' for length: 25.57 kts
Power going to wave formation at top speed: 60 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 2.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 25.00 ft / 7.62 m
- Forecastle (35 %): 23.00 ft / 7.01 m
- Mid (35 %): 23.00 ft / 7.01 m (15.00 ft / 4.57 m aft of break)
- Quarterdeck (15 %): 15.00 ft / 4.57 m
- Stern: 15.00 ft / 4.57 m
- Average freeboard: 18.08 ft / 5.51 m
Ship tends to be wet forward
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 136.2 %
- Above water (accommodation/working, high = better): 109.0 %
Waterplane Area: 16,138 Square feet or 1,499 Square metres
Displacement factor (Displacement / loading): 96 %
Structure weight / hull surface area: 85 lbs/sq ft or 413 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.94
- Longitudinal: 1.75
- Overall: 1.00
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is adequate
This is a forum for discussion of topics relating to the Dreadnought era, prior to the ascendency of naval aviation. We will be discussing history, ship design, and naval wargaming.
Sunday, January 23, 2005
A (relatively) fast protected cruiser
In my quest for very fast ships, I just tried a British light cruiser for 1921 that only has a 2in protective deck and can make 33 knots. My requirement is for a good seaboat and stability, so that had to be taken into account. I also want good strength, not something that is very lightly built and easily damaged. I started with 462ft x 46ft x 15ft, and went from there. I had wanted 35 knots, which should be doable, but is not with Springsharp. I had to narrow the hull, deepen the draft, go from flush-decked to a raised forecastle, to make the design work. The armament is what I think is appropriate for such a ship: 9-5.5in QF and 8-4.7in DP guns. Needless to say, the size ballooned, as is usual with my Springsharp designs. Occasionally, I will be surprised, and that doesn't happen, but with fast ships, it is often true. I find that I still don't have a really good handle on how to specify freeboard, as I have been showing the raised forecastle wrong. This is the report:
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