The ABS war told RSAN high ranks they completely missed river warfare in their plans and doctrines. Learning the hard war the RSAN is now interested in having some river/coastal gun boats.
Below is one of the proposed designs. What do you think?
RGB37A, South African River Gun Boat laid down 1937
Displacement:
460 t light; 490 t standard; 552 t normal; 602 t full load
Dimensions: Length overall / water x beam x draught
219,31 ft / 213,25 ft x 25,59 ft x 5,91 ft (normal load)
66,85 m / 65,00 m x 7,80 m x 1,80 m
Armament:
4 - 4,13" / 105 mm guns (2x2 guns), 35,32lbs / 16,02kg shells, 1937 Model
Breech loading guns in deck mounts
on centreline ends, evenly spread
4 - 1,57" / 40,0 mm guns (2x2 guns), 1,95lbs / 0,88kg shells, 1937 Model
Anti-aircraft guns in deck mounts
on side, all amidships, all raised mounts - superfiring
4 - 0,79" / 20,0 mm guns (2x2 guns), 0,24lbs / 0,11kg shells, 1937 Model
Anti-aircraft guns in deck mounts
on centreline ends, evenly spread
Weight of broadside 150 lbs / 68 kg
Shells per gun, main battery: 220
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 0,79" / 20 mm 98,43 ft / 30,00 m 6,56 ft / 2,00 m
Ends: Unarmoured
Main Belt covers 71% of normal length
Main belt does not fully cover magazines and engineering spaces
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1,18" / 30 mm 0,79" / 20 mm -
2nd: 0,59" / 15 mm - -
3rd: 0,39" / 10 mm - -
Machinery:
Coal fired boilers, complex reciprocating steam engines,
Geared drive, 2 shafts, 2.500 ihp / 1.865 Kw = 18,38 kts
Range 2.500nm at 12,00 kts
Bunker at max displacement = 112 tons (100% coal)
Complement:
56 - 74
Cost:
£0,291 million / $1,162 million
Distribution of weights at normal displacement:
Armament: 19 tons, 3,4%
Armour: 34 tons, 6,1%
- Belts: 23 tons, 4,2%
- Torpedo bulkhead: 0 tons, 0,0%
- Armament: 11 tons, 1,9%
- Armour Deck: 0 tons, 0,0%
- Conning Tower: 0 tons, 0,0%
Machinery: 153 tons, 27,7%
Hull, fittings & equipment: 205 tons, 37,0%
Fuel, ammunition & stores: 92 tons, 16,7%
Miscellaneous weights: 50 tons, 9,1%
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
488 lbs / 222 Kg = 13,8 x 4,1 " / 105 mm shells or 0,3 torpedoes
Stability (Unstable if below 1.00): 1,24
Metacentric height 1,0 ft / 0,3 m
Roll period: 11,0 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0,25
Seaboat quality (Average = 1.00): 1,00
Hull form characteristics:
Hull has a flush deck
Block coefficient: 0,600
Length to Beam Ratio: 8,33 : 1
'Natural speed' for length: 14,60 kts
Power going to wave formation at top speed: 55 %
Trim (Max stability = 0, Max steadiness = 100): 70
Bow angle (Positive = bow angles forward): 20,00 degrees
Stern overhang: 1,64 ft / 0,50 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 12,14 ft / 3,70 m
- Forecastle (20%): 7,55 ft / 2,30 m
- Mid (44%): 7,55 ft / 2,30 m
- Quarterdeck (15%): 7,55 ft / 2,30 m
- Stern: 7,55 ft / 2,30 m
- Average freeboard: 7,91 ft / 2,41 m
Ship tends to be wet forward
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 126,9%
- Above water (accommodation/working, high = better): 102,4%
Waterplane Area: 3.991 Square feet or 371 Square metres
Displacement factor (Displacement / loading): 102%
Structure weight / hull surface area: 36 lbs/sq ft or 175 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0,97
- Longitudinal: 1,32
- Overall: 1,00
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is adequate
Ship has slow, easy roll, a good, steady gun platform
NOTE: Armor is meant to protect magazines and boilers only.