Project 91A Orfei, Russian Minelayer (Minny i Setevoy Zagraditel') laid down 1949
Displacement:
3,683 t light; 3,839 t standard; 4,731 t normal; 5,446 t full load
Dimensions: Length overall / water x beam x draught
475.72 ft / 475.72 ft x 48.23 ft x 13.12 ft (normal load)
145.00 m / 145.00 m x 14.70 m x 4.00 m
Armament:
6 - 3.94" / 100 mm guns (3x2 guns), 37.48lbs / 17.00kg shells, 1949 Model
Automatic rapid fire guns in deck mounts with hoists
on centreline ends, majority forward, 1 raised mount - superfiring
8 - 1.46" / 37.0 mm guns (4x2 guns), 1.55lbs / 0.70kg shells, 1949 Model
Anti-aircraft guns in deck mounts
on side, all amidships, all raised mounts - superfiring
4 - 0.55" / 14.0 mm guns in single mounts, 0.08lbs / 0.04kg shells, 1949 Model
Machine guns in deck mounts
on side, evenly spread
Weight of broadside 238 lbs / 108 kg
Shells per gun, main battery: 450
Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.98" / 25 mm 0.20" / 5 mm 0.20" / 5 mm
2nd: 0.20" / 5 mm - -
3rd: 0.20" / 5 mm - -
- Conning tower: 0.98" / 25 mm
Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 78,169 shp / 58,314 Kw = 34.00 kts
Range 3,400nm at 25.00 kts
Bunker at max displacement = 1,607 tons
Complement:
284 - 370
Cost:
£3.191 million / $12.765 million
Distribution of weights at normal displacement:
Armament: 29 tons, 0.6 %
Armour: 13 tons, 0.3 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 7 tons, 0.2 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 6 tons, 0.1 %
Machinery: 1,890 tons, 39.9 %
Hull, fittings & equipment: 1,550 tons, 32.8 %
Fuel, ammunition & stores: 1,049 tons, 22.2 %
Miscellaneous weights: 200 tons, 4.2 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
2,923 lbs / 1,326 Kg = 95.8 x 3.9 " / 100 mm shells or 0.7 torpedoes
Stability (Unstable if below 1.00): 1.28
Metacentric height 2.6 ft / 0.8 m
Roll period: 12.6 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.15
Seaboat quality (Average = 1.00): 1.08
Hull form characteristics:
Hull has rise forward of midbreak
Block coefficient: 0.550
Length to Beam Ratio: 9.86 : 1
'Natural speed' for length: 21.81 kts
Power going to wave formation at top speed: 65 %
Trim (Max stability = 0, Max steadiness = 100): 65
Bow angle (Positive = bow angles forward): 0.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 24.61 ft / 7.50 m
- Forecastle (25 %): 23.79 ft / 7.25 m
- Mid (50 %): 22.97 ft / 7.00 m (16.08 ft / 4.90 m aft of break)
- Quarterdeck (15 %): 16.08 ft / 4.90 m
- Stern: 16.08 ft / 4.90 m
- Average freeboard: 19.91 ft / 6.07 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 139.7 %
- Above water (accommodation/working, high = better): 205.3 %
Waterplane Area: 16,012 Square feet or 1,488 Square metres
Displacement factor (Displacement / loading): 112 %
Structure weight / hull surface area: 55 lbs/sq ft or 270 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.68
- Longitudinal: 1.71
- Overall: 0.75
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
Breakdown of Miscellaneous Weights:
Not yet available.
Ships in Class:
- Orfei
- Evstafi