Design 46EC Version 2, French Experimental Cruiser designed in 1946
The Design 46EC was an experimental vessel designed to evaluate a proposed new type of armament. Although the size of a large destroyer, Design 46EC would be equipped with four (later reduced to three) large single turrets with an automatic 20cm/L55 gun designed to fire at a rate of twelve rounds per minute. In theory, this would allow destroyer-sized ships to overpower their opposition at extremely long ranges and quickly disable them with high-caliber hits, finishing them off before getting into range of the enemy guns.
A single 20cm automatic mounting was trialed in the early 1940s, and a degree of success was achieved. The 20cm/L55 automatic gun eventually went into service in triple turrets aboard the Suffren-class cruisers, where they were a satisfactory success, achieving a reliable eight to nine rounds per minute rate of fire.
However, detail blueprints of Design 46EC demonstrated that the topweight of the turrets presented a significant problem. Although one of the aft turrets was deleted from the design, this reduced the expected efficiency against enemy vessels. Concerns also rose about the effects that firing vibrations would cause upon the lightly-built barbettes. Finally, it became clear that the 20cm guns had no capability to fire as dual-purpose anti-aircraft guns (particularly beyond their maximum elevation of 45 degrees), and in December of 1946, the Marine Nationale decided to cancel plans to build a testbed ship.
Displacement:
4,000 t light; 4,199 t standard; 4,975 t normal; 5,596 t full load
Dimensions: Length overall / water x beam x draught
501.68 ft / 492.13 ft x 49.54 ft x 15.75 ft (normal load)
152.91 m / 150.00 m x 15.10 m x 4.80 m
Armament:
3 - 7.87" / 200 mm guns in single mounts, 286.60lbs / 130.00kg shells, 1946 Model
Automatic rapid fire guns in turrets (on barbettes)
on centreline ends, majority forward, 1 raised mount
8 - 2.24" / 57.0 mm guns (4x2 guns), 6.61lbs / 3.00kg shells, 1946 Model
Automatic rapid fire guns in deck mounts with hoists
on side, all amidships
16 - 0.79" / 20.0 mm guns (8x2 guns), 0.24lbs / 0.11kg shells, 1946 Model
Machine guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 917 lbs / 416 kg
Shells per gun, main battery: 190
Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.97" / 50 mm 0.79" / 20 mm 0.79" / 20 mm
2nd: 0.59" / 15 mm 0.20" / 5 mm 0.20" / 5 mm
3rd: 0.59" / 15 mm - -
- Conning tower: 1.97" / 50 mm
Machinery:
Oil fired boilers, steam turbines plus diesel motors,
Electric motors, 2 shafts, 63,377 shp / 47,279 Kw = 34.00 kts
Range 7,500nm at 18.00 kts
Bunker at max displacement = 1,397 tons
Complement:
296 - 385
Cost:
£3.262 million / $13.046 million
Distribution of weights at normal displacement:
Armament: 117 tons, 2.4 %
Armour: 65 tons, 1.3 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 52 tons, 1.1 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 12 tons, 0.2 %
Machinery: 1,583 tons, 31.8 %
Hull, fittings & equipment: 1,905 tons, 38.3 %
Fuel, ammunition & stores: 975 tons, 19.6 %
Miscellaneous weights: 330 tons, 6.6 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
3,382 lbs / 1,534 Kg = 13.9 x 7.9 " / 200 mm shells or 0.8 torpedoes
Stability (Unstable if below 1.00): 1.13
Metacentric height 2.2 ft / 0.7 m
Roll period: 14.1 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.59
Seaboat quality (Average = 1.00): 1.21
Hull form characteristics:
Hull has rise forward of midbreak
and transom stern
Block coefficient: 0.454
Length to Beam Ratio: 9.93 : 1
'Natural speed' for length: 25.48 kts
Power going to wave formation at top speed: 62 %
Trim (Max stability = 0, Max steadiness = 100): 58
Bow angle (Positive = bow angles forward): 20.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 26.25 ft / 8.00 m
- Forecastle (25 %): 24.61 ft / 7.50 m
- Mid (50 %): 22.97 ft / 7.00 m (15.75 ft / 4.80 m aft of break)
- Quarterdeck (15 %): 15.75 ft / 4.80 m
- Stern: 15.75 ft / 4.80 m
- Average freeboard: 20.14 ft / 6.14 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 128.9 %
- Above water (accommodation/working, high = better): 199.1 %
Waterplane Area: 16,202 Square feet or 1,505 Square metres
Displacement factor (Displacement / loading): 111 %
Structure weight / hull surface area: 66 lbs/sq ft or 322 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.69
- Longitudinal: 1.98
- Overall: 0.77
Caution: Hull subject to strain in open-sea
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform
Good seaboat, rides out heavy weather easily
Each single 20cm auto turret weighs 45 tons in Springsharp. 45
Breakdown of Miscellaneous Weight:
- 45 tons for A turret automation
- 45 tons for B turret automation
- 45 tons for X turret automation
135 tons total, 195 tons remaining