(Historical data)
A-3, laid down 1942
A-4, laid down 1942
A-5, laid down 1942
A-6, laid down 1942
A-7, laid down 1943
A-8, laid down 1943
A-3 class minesweeper, laid down 1941
Displacement: 396 t light; 417 t standard; 515 t normal; 594 t full load
Dimensions: Length overall / water x beam x draught
167.67 ft / 161.09 ft x 26.25 ft x 8.20 ft (normal load)
51.11 m / 49.10 m x 8.00 m x 2.50 m
Armament:
2 - 4.13" / 105 mm guns in single mounts, 35.32lbs / 16.02kg shells, 1941 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, evenly spread, 1 raised mount
2 - 1.46" / 37.0 mm guns in single mounts, 1.55lbs / 0.70kg shells, 1941 Model
Anti-aircraft guns in deck mounts
on side, all amidships
8 - 0.79" / 20.0 mm guns in single mounts, 0.24lbs / 0.11kg shells, 1941 Model
Anti-aircraft guns in deck mounts
on side, all aft
Weight of broadside 76 lbs / 34 kg
Shells per gun, main battery: 250
Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.98" / 25 mm - -
2nd: 0.59" / 15 mm - -
3rd: 0.59" / 15 mm - -
Machinery:
Diesel Internal combustion motors,
Direct drive, 2 shafts, 3,000 shp / 2,238 Kw = 18.81 kts
Range 4,000nm at 15.00 kts (Bunkerage = 176 tons)
Complement: 53 - 70
Cost: £0.203 million / $0.814 million
Distribution of weights at normal displacement:
Armament: 9 tons, 1.8 %
Armour: 5 tons, 1.0 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 5 tons, 1.0 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 79 tons, 15.4 %
Hull, fittings & equipment: 218 tons, 42.3 %
Fuel, ammunition & stores: 119 tons, 23.2 %
Miscellaneous weights: 84 tons, 16.3 %
-50 t: Boom for minesweeping/salvage/target-towing
-14 t: Weight reserve
-10 t: Depth charges and throwers
-10 t: ASDIC
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
921 lbs / 418 Kg = 26.1 x 4.1 " / 105 mm shells or 0.6 torpedoes
Stability (Unstable if below 1.00): 1.11
Metacentric height 0.8 ft / 0.2 m
Roll period: 12.2 seconds
Steadiness - As gun platform (Average = 50 %): 51 %
- Recoil effect (Restricted arc if above 1.00): 0.37
Seaboat quality (Average = 1.00): 1.41
Hull form characteristics:
Hull has rise forward of midbreak
Block coefficient: 0.520
Length to Beam Ratio: 6.14 : 1
'Natural speed' for length: 12.69 kts
Power going to wave formation at top speed: 67 %
Trim (Max stability = 0, Max steadiness = 100): 36
Bow angle (Positive = bow angles forward): 10.00 degrees
Stern overhang: 3.28 ft / 1.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 18.70 ft / 5.70 m
- Forecastle (20 %): 15.75 ft / 4.80 m
- Mid (50 %): 15.75 ft / 4.80 m (7.87 ft / 2.40 m aft of break)
- Quarterdeck (15 %): 7.87 ft / 2.40 m
- Stern: 7.87 ft / 2.40 m
- Average freeboard: 12.05 ft / 3.67 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 83.4 %
- Above water (accommodation/working, high = better): 118.7 %
Waterplane Area: 2,869 Square feet or 267 Square metres
Displacement factor (Displacement / loading): 159 %
Structure weight / hull surface area: 39 lbs/sq ft or 188 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.79
- Longitudinal: 8.06
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is adequate
Good seaboat, rides out heavy weather easily