After news of the RSAN's attack on the Brazillian navy at Rio de Janerio reached Germany, plans were put in place to try to make a similar attack on German harbors more difficult. This vessel is one of the counter-tactics: a floating AA battery to be deployed on the seaward approaches to the harbor. From there it could attempt to detect and engage any approaching threat aircraft, using it's radar and searchlights to spot the threat. Additionally, it can serve a similar purpose against any small torpedo craft, making use of it's shallow-draft design to limit the threat such craft pose to it.
FB-1, German Floating AA battery laid down 1935
Displacement:
473 t light; 525 t standard; 530 t normal; 533 t full load
Dimensions: Length overall / water x beam x draught
169.96 ft / 164.04 ft x 32.81 ft x 5.74 ft (normal load)
51.80 m / 50.00 m x 10.00 m x 1.75 m
Armament:
4 - 4.13" / 105 mm guns (2x2 guns), 35.32lbs / 16.02kg shells, 1928 Model
Dual purpose guns in deck mounts
on centreline ends, evenly spread
4 - 1.46" / 37.0 mm guns (2x2 guns), 1.55lbs / 0.70kg shells, 1929 Model
Anti-aircraft guns in deck mounts
on centreline ends, evenly spread, all raised mounts - superfiring
24 - 0.79" / 20.0 mm guns (6x4 guns), 0.24lbs / 0.11kg shells, 1935 Model
Machine guns in deck mounts
on side, evenly spread, 4 raised mounts
Weight of broadside 153 lbs / 70 kg
Shells per gun, main battery: 450
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 1.97" / 50 mm 164.04 ft / 50.00 m 7.51 ft / 2.29 m
Ends: Unarmoured
Main Belt covers 154 % of normal length
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.18" / 30 mm 0.79" / 20 mm -
2nd: 0.79" / 20 mm 0.39" / 10 mm -
3rd: 0.39" / 10 mm - -
- Armour deck: 1.18" / 30 mm, Conning tower: 1.97" / 50 mm
Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 543 shp / 405 Kw = 12.00 kts
Range 1,000nm at 5.00 kts
Bunker at max displacement = 8 tons
Complement:
54 - 71
Cost:
£0.177 million / $0.709 million
Distribution of weights at normal displacement:
Armament: 19 tons, 3.6 %
Armour: 191 tons, 36.0 %
- Belts: 90 tons, 16.9 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 12 tons, 2.3 %
- Armour Deck: 86 tons, 16.2 %
- Conning Tower: 3 tons, 0.5 %
Machinery: 15 tons, 2.9 %
Hull, fittings & equipment: 208 tons, 39.3 %
Fuel, ammunition & stores: 56 tons, 10.6 %
Miscellaneous weights: 40 tons, 7.6 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1,725 lbs / 782 Kg = 48.8 x 4.1 " / 105 mm shells or 1.2 torpedoes
Stability (Unstable if below 1.00): 1.37
Metacentric height 1.6 ft / 0.5 m
Roll period: 10.8 seconds
Steadiness - As gun platform (Average = 50 %): 94 %
- Recoil effect (Restricted arc if above 1.00): 0.16
Seaboat quality (Average = 1.00): 1.88
Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.600
Length to Beam Ratio: 5.00 : 1
'Natural speed' for length: 12.81 kts
Power going to wave formation at top speed: 45 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 15.00 degrees
Stern overhang: 3.28 ft / 1.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 9.84 ft / 3.00 m
- Forecastle (20 %): 9.02 ft / 2.75 m
- Mid (50 %): 9.02 ft / 2.75 m
- Quarterdeck (15 %): 9.02 ft / 2.75 m
- Stern: 9.02 ft / 2.75 m
- Average freeboard: 9.09 ft / 2.77 m
Ship tends to be wet forward
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 52.4 %
- Above water (accommodation/working, high = better): 125.3 %
Waterplane Area: 3,936 Square feet or 366 Square metres
Displacement factor (Displacement / loading): 128 %
Structure weight / hull surface area: 40 lbs/sq ft or 194 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.92
- Longitudinal: 2.72
- Overall: 1.03
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform
Excellent seaboat, comfortable, can fire her guns in the heaviest weather
40 tons for radar
5 tons for additional searchlights
This post has been edited 1 times, last edit by "Hrolf Hakonson" (Aug 6th 2009, 3:26am)