F - Class Frigate
Six vessels laid down 1938
F1, F2, F3, F4, F5, F6
Six vessels laid down 1939
F7, F8, F9, F10, F11, F12
An anti-submarine frigate more suited to open ocean work to augment the previous Vespa and Diana Classes. The new design offers greater capability against submarine and aircraft threats whilst remaining cheap to construct.
The propulsion is the same as the previous Diana Class, with diesel and electric drive, giving long range, rapid response and quiet running at low speeds.
The main armament consists of three 76/62 single weapons. This gun was developed from the 65/64 automatic weapons program. Towards the end of 1937 it was felt that the basis of the weapon's employment had change and a larger calibre was needed to deal with surface threats. As a result, a 76mm gun was built on the same principles, with a heavier shell, a slight reduction in muzzle velocity giving a slightly shorter barrel. The development of the automatic feed continued but in the mean time a manually loaded version was adopted. This is in an enclosed weatherproof mounting with RPC. The mountings are controlled from the two lightweight GDR5 directors. Against aircraft it is expected to give much improved results than the previous classes' armament whilst retaining ability against likely surface threats. The gun armament is rounded out by twelve individual 25mm guns. The anti-submarine armament is unchanged from previous classes, with a quadruple lanciabombe weapon mounted aft and a scariabombe mounted on the fantail. A new more advanced D5 sonar set with better passive ability is mounted for the first time.
Habitability is expected to be good, with a larger superstructure for accommodation spaces than in previous classes, and a more spacious enclosed bridge. The new flush deck has lead to improved structural strength, which along with higher freeboard and thicker hull plating, will give improved capability in heavier seas. It is expected that the ship type will be the mainstay of oceanic escorts.
Fregata Antisom laid down 1938
Displacement:
1,253 t light; 1,310 t standard; 1,570 t normal; 1,777 t full load
Dimensions: Length (overall / waterline) x beam x draught (normal/deep)
(307.51 ft / 295.28 ft) x 35.79 ft x (11.15 / 12.19 ft)
(93.73 m / 90.00 m) x 10.91 m x (3.40 / 3.72 m)
Armament:
3 - 3.00" / 76.2 mm 62.0 cal guns - 13.78lbs / 6.25kg shells, 500 per gun
Anti-air guns in deck and hoist mounts, 1938 Model
3 x Single mounts on centreline ends, evenly spread
1 raised mount - superfiring
12 - 0.98" / 25.0 mm 77.0 cal guns - 0.54lbs / 0.24kg shells, 4,000 per gun
Anti-air guns in deck mounts, 1938 Model
12 x Single mounts on sides amidships
Weight of broadside 48 lbs / 22 kg
Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.18" / 30 mm 0.79" / 20 mm 0.79" / 20 mm
2nd: 0.39" / 10 mm - -
- Conning towers: Forward 2.76" / 70 mm, Aft 0.00" / 0 mm
Machinery:
Diesel Internal combustion motors,
Electric cruising motors plus geared drives, 2 shafts, 8,000 shp / 5,968 Kw = 22.26 kts
Range 6,000nm at 15.00 kts
Bunker at max displacement = 467 tons
Complement:
124 - 162
Cost:
£0.461 million / $1.843 million
Distribution of weights at normal displacement:
Armament: 20 tons, 1.3 %
Armour: 26 tons, 1.6 %
- Armament: 18 tons, 1.1 %
- Conning Tower: 8 tons, 0.5 %
Machinery: 219 tons, 14.0 %
Hull, fittings & equipment: 845 tons, 53.8 %
Fuel, ammunition & stores: 317 tons, 20.2 %
Miscellaneous weights: 143 tons, 9.1 %
- Hull below water: 24 tons
- On freeboard deck: 89 tons
- Above deck: 30 tons
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
4,915 lbs / 2,230 Kg = 364.1 x 3.0 " / 76 mm shells or 1.7 torpedoes
Stability (Unstable if below 1.00): 1.18
Metacentric height 1.5 ft / 0.4 m
Roll period: 12.4 seconds
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0.08
Seaboat quality (Average = 1.00): 2.00
Hull form characteristics:
Hull has a flush deck,
a normal bow and small transom stern
Block coefficient (normal/deep): 0.466 / 0.483
Length to Beam Ratio: 8.25 : 1
'Natural speed' for length: 18.65 kts
Power going to wave formation at top speed: 55 %
Trim (Max stability = 0, Max steadiness = 100): 25
Bow angle (Positive = bow angles forward): 20.00 degrees
Stern overhang: 3.28 ft / 1.00 m
Freeboard (% = length of deck as a percentage of waterline length):
Fore end, Aft end
- Forecastle: 20.00 %, 24.61 ft / 7.50 m, 19.69 ft / 6.00 m
- Forward deck: 20.00 %, 19.69 ft / 6.00 m, 16.40 ft / 5.00 m
- Aft deck: 35.00 %, 16.40 ft / 5.00 m, 14.76 ft / 4.50 m
- Quarter deck: 25.00 %, 14.76 ft / 4.50 m, 14.76 ft / 4.50 m
- Average freeboard: 17.08 ft / 5.21 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 53.8 %
- Above water (accommodation/working, high = better): 177.0 %
Waterplane Area: 6,993 Square feet or 650 Square metres
Displacement factor (Displacement / loading): 232 %
Structure weight / hull surface area: 60 lbs/sq ft or 293 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.03
- Longitudinal: 6.63
- Overall: 1.25
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is excellent
Excellent seaboat, comfortable, can fire her guns in the heaviest weather
10t per 76/62 mounting
1t per 25mm mounting
10t = 2 x GDR.5 FCS
15t = D5 sonar
7t = Scaricabombe
10t = Lanciabombe AS
50t = 150 Depth charges
9t = 250hp electric creeping motors
121tons
8knts on creeping motors