GB/CB/1915 design study, Great Britain Battlecruiser laid down 1915 (Engine 1950)
Displacement:
34,888 t light; 36,564 t standard; 39,099 t normal; 41,127 t full load
Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(855.20 ft / 850.00 ft) x 105.00 ft x (25.90 / 27.00 ft)
(260.67 m / 259.08 m) x 32.00 m x (7.89 / 8.23 m)
Armament:
8 - 15.00" / 381 mm 45.0 cal guns - 1,950.00lbs / 884.51kg shells, 90 per gun
Breech loading guns in turret on barbette mounts, 1915 Model
4 x Twin mounts on centreline ends, evenly spread
2 raised mounts - superfiring
16 - 5.50" / 140 mm 45.0 cal guns - 85.00lbs / 38.56kg shells, 150 per gun
Quick firing guns in deck and hoist mounts, 1915 Model
16 x Single mounts on sides, evenly spread
4 raised mounts
Weight of broadside 16,960 lbs / 7,693 kg
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 8.00" / 203 mm 565.00 ft / 172.21 m 9.00 ft / 2.74 m
Ends: Unarmoured
Upper: 5.00" / 127 mm 565.00 ft / 172.21 m 9.00 ft / 2.74 m
Main Belt covers 102 % of normal length
- Torpedo Bulkhead:
2.00" / 51 mm 565.00 ft / 172.21 m 25.90 ft / 7.89 m
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 8.00" / 203 mm 5.00" / 127 mm 8.00" / 203 mm
2nd: 4.00" / 102 mm 3.00" / 76 mm 4.00" / 102 mm
- Protected deck - multiple decks: 3.00" / 76 mm For and Aft decks
Forecastle: 3.00" / 76 mm Quarter deck: 3.00" / 76 mm
- Conning towers: Forward 8.00" / 203 mm, Aft 0.00" / 0 mm
Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 184,470 shp / 137,614 Kw = 32.00 kts
Range 6,500nm at 18.00 kts
Bunker at max displacement = 4,563 tons
Complement:
1,389 - 1,807
Cost:
£4.706 million / $18.825 million
Distribution of weights at normal displacement:
Armament: 2,618 tons, 6.7 %
Armour: 10,219 tons, 26.1 %
- Belts: 2,789 tons, 7.1 %
- Torpedo bulkhead: 1,083 tons, 2.8 %
- Armament: 2,527 tons, 6.5 %
- Armour Deck: 3,621 tons, 9.3 %
- Conning Tower: 199 tons, 0.5 %
Machinery: 4,413 tons, 11.3 %
Hull, fittings & equipment: 17,638 tons, 45.1 %
Fuel, ammunition & stores: 4,210 tons, 10.8 %
Miscellaneous weights: 0 tons, 0.0 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
71,119 lbs / 32,259 Kg = 42.1 x 15.0 " / 381 mm shells or 10.5 torpedoes
Stability (Unstable if below 1.00): 1.13
Metacentric height 6.8 ft / 2.1 m
Roll period: 16.9 seconds
Steadiness - As gun platform (Average = 50 %): 64 %
- Recoil effect (Restricted arc if above 1.00): 0.89
Seaboat quality (Average = 1.00): 1.28
Hull form characteristics:
Hull has rise forward of midbreak,
a normal bow and a cruiser stern
Block coefficient (normal/deep): 0.592 / 0.597
Length to Beam Ratio: 8.10 : 1
'Natural speed' for length: 29.15 kts
Power going to wave formation at top speed: 52 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 8.00 degrees
Stern overhang: -3.00 ft / -0.91 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 34.00 %, 37.00 ft / 11.28 m, 32.00 ft / 9.75 m
- Forward deck: 33.00 %, 32.00 ft / 9.75 m, 32.00 ft / 9.75 m
- Aft deck: 18.00 %, 24.00 ft / 7.32 m, 24.00 ft / 7.32 m
- Quarter deck: 15.00 %, 24.00 ft / 7.32 m, 26.00 ft / 7.92 m
- Average freeboard: 30.19 ft / 9.20 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 85.9 %
- Above water (accommodation/working, high = better): 259.2 %
Waterplane Area: 64,789 Square feet or 6,019 Square metres
Displacement factor (Displacement / loading): 121 %
Structure weight / hull surface area: 202 lbs/sq ft or 985 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.96
- Longitudinal: 1.42
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Good seaboat, rides out heavy weather easily
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.
Tuesday, September 18, 2007
A more normal GB/CB/1915 alternative design
I wondered what the GB/CB/1915 would be like with a more normal speed for the sort of power that I had envisioned. The answer is that just 32 knots seems reasonable. This design still requires the lightest possible machinery. This is the revised Springsharp report:
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