A couple of heavy cruisers and a rebuilt trials ship.
Beyond the Wiltshire Class the Admiralty looked at another repeat Northumberland. The DNC offered a modernised design (CA6) with the new YARD powerplant, in this case three 30,000hp units giving a three-shaft layout. The belt armour was modified to that of the Wiltshire so the overall effect has been to reduce weight and cost with the benefits of improved speed and increased range (1,000nm at 20kts). The DNC then offered a further improved version (CA6a) with the 4.5in battery replaced by eight twin 3in L/50 and the new 57mm quad mount which offered even more weight saving and formidable anti-aircraft firepower. A modernised fire-control suite is also to be fitted. Four ships will be completed as the Cumberland Class.
Cumberland Class, Great Britain Heavy Cruiser laid down 1949
Displacement:
12,737 t light; 13,499 t standard; 15,830 t normal; 17,695 t full load
Dimensions: Length overall / water x beam x draught
661.91 ft / 655.00 ft x 76.00 ft x 21.00 ft (normal load)
201.75 m / 199.64 m x 23.16 m x 6.40 m
Armament:
9 - 7.50" / 191 mm guns (3x3 guns), 250.00lbs / 113.40kg shells, 1945 Model
Automatic rapid fire guns in turrets (on barbettes)
on centreline ends, majority forward, 1 raised mount - superfiring
16 - 3.00" / 76.2 mm guns (8x2 guns), 12.50lbs / 5.67kg shells, 1950 Model
Automatic rapid fire guns in deck mounts with hoists
on side ends, evenly spread
16 - 2.24" / 57.0 mm guns (4x4 guns), 6.00lbs / 2.72kg shells, 1950 Model
Anti-aircraft guns in deck mounts
on side, all amidships, all raised mounts - superfiring
4 - 1.57" / 40.0 mm guns (2x2 guns), 2.00lbs / 0.91kg shells, 1945 Model
Anti-aircraft guns in deck mounts
on side, all aft, all raised mounts - superfiring
Weight of broadside 2,554 lbs / 1,158 kg
Shells per gun, main battery: 300
12 - 24.5" / 622.3 mm above water torpedoes
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 6.00" / 152 mm 350.00 ft / 106.68 m 13.00 ft / 3.96 m
Ends: Unarmoured
Main Belt covers 82 % of normal length
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 6.00" / 152 mm 3.00" / 76 mm 4.00" / 102 mm
2nd: 1.00" / 25 mm 1.00" / 25 mm 2.00" / 51 mm
3rd: 1.00" / 25 mm 1.00" / 25 mm -
4th: 0.50" / 13 mm 0.50" / 13 mm -
- Armour deck: 3.00" / 76 mm, Conning tower: 1.00" / 25 mm
Machinery:
Oil fired boilers, steam turbines,
Electric motors, 3 shafts, 90,000 shp / 67,140 Kw = 31.43 kts
Range 9,000nm at 20.00 kts
Bunker at max displacement = 4,197 tons
Complement:
705 - 917
Cost:
£7.844 million / $31.376 million
Distribution of weights at normal displacement:
Armament: 329 tons, 2.1 %
Armour: 3,648 tons, 23.0 %
- Belts: 1,196 tons, 7.6 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 469 tons, 3.0 %
- Armour Deck: 1,969 tons, 12.4 %
- Conning Tower: 14 tons, 0.1 %
Machinery: 2,176 tons, 13.7 %
Hull, fittings & equipment: 6,134 tons, 38.7 %
Fuel, ammunition & stores: 3,093 tons, 19.5 %
Miscellaneous weights: 450 tons, 2.8 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
31,663 lbs / 14,362 Kg = 150.1 x 7.5 " / 191 mm shells or 3.4 torpedoes
Stability (Unstable if below 1.00): 1.19
Metacentric height 4.6 ft / 1.4 m
Roll period: 14.9 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.34
Seaboat quality (Average = 1.00): 1.20
Hull form characteristics:
Hull has rise forward of midbreak
and transom stern
Block coefficient: 0.530
Length to Beam Ratio: 8.62 : 1
'Natural speed' for length: 29.45 kts
Power going to wave formation at top speed: 55 %
Trim (Max stability = 0, Max steadiness = 100): 58
Bow angle (Positive = bow angles forward): 12.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 32.50 ft / 9.91 m
- Forecastle (20 %): 26.00 ft / 7.92 m
- Mid (65 %): 23.00 ft / 7.01 m (16.00 ft / 4.88 m aft of break)
- Quarterdeck (20 %): 16.00 ft / 4.88 m
- Stern: 17.90 ft / 5.46 m
- Average freeboard: 22.54 ft / 6.87 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 66.2 %
- Above water (accommodation/working, high = better): 166.0 %
Waterplane Area: 35,483 Square feet or 3,296 Square metres
Displacement factor (Displacement / loading): 143 %
Structure weight / hull surface area: 120 lbs/sq ft or 584 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.96
- Longitudinal: 1.35
- Overall: 1.00
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
Good seaboat, rides out heavy weather easily
Class Names: Cumberland, Devonshire, Norfolk, Antrim
RDF Sets
One Aerial Search Type 971 set
One Surface Search Type 970 set
One Height-Finder and Surface Search Type 277 set
Two LRS1 fire-control systems using LRS Directors with twin Type 901 RDF sets
Three MRS7 fire-control systems using Mk.6M Gunnery Directors with twin Type 988 RDF sets and Simple Electric Deflection Calculator and Flyplane
Four MRS8 fire-control systems using Close-Range Blind Fire (CRBF) directors with Type 262 RDF sets
HF/DF Type 292
Passive Intercept Type UA1
Four RU-series jammers
ASDIC Type 146M
The four Howe Class cruisers will be refitted with updated electronics and fire-control systems and will lose their catapults and aircraft.
Howe Class, Great Britain Heavy Cruiser laid down 1927 (Engine 1942)
Displacement:
9,910 t light; 10,387 t standard; 11,865 t normal; 13,048 t full load
Dimensions: Length overall / water x beam x draught
615.64 ft / 610.00 ft x 68.25 ft x 19.00 ft (normal load)
187.65 m / 185.93 m x 20.80 m x 5.79 m
Armament:
8 - 8.00" / 203 mm guns (4x2 guns), 290.00lbs / 131.54kg shells, 1927 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, evenly spread, 2 raised mounts - superfiring
8 - 4.50" / 114 mm guns (4x2 guns), 45.56lbs / 20.67kg shells, 1938 Model
Dual purpose guns in deck mounts with hoists
on side, all amidships
8 - 2.24" / 57.0 mm guns (4x2 guns), 5.65lbs / 2.56kg shells, 1946 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, all raised mounts
12 - 1.57" / 40.0 mm guns (6x2 guns), 1.95lbs / 0.88kg shells, 1941 Model
Anti-aircraft guns in deck mounts
on side ends, evenly spread, all raised mounts - superfiring
Weight of broadside 2,753 lbs / 1,249 kg
Shells per gun, main battery: 150
6 - 24.5" / 622.3 mm above water torpedoes
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 2.00" / 51 mm 300.00 ft / 91.44 m 12.00 ft / 3.66 m
Ends: 4.00" / 102 mm 100.00 ft / 30.48 m 12.00 ft / 3.66 m
210.00 ft / 64.01 m Unarmoured ends
Main Belt covers 76 % of normal length
Main belt does not fully cover magazines and engineering spaces
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 3.00" / 76 mm 2.00" / 51 mm 1.00" / 25 mm
2nd: 1.00" / 25 mm 0.50" / 13 mm 1.00" / 25 mm
3rd: 0.50" / 13 mm 0.50" / 13 mm -
4th: 0.50" / 13 mm 0.50" / 13 mm -
- Armour deck: 2.00" / 51 mm, Conning tower: 1.00" / 25 mm
Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 88,058 shp / 65,692 Kw = 31.35 kts
Range 10,000nm at 16.00 kts
Bunker at max displacement = 2,662 tons
Complement:
567 - 738
Cost:
£3.380 million / $13.519 million
Distribution of weights at normal displacement:
Armament: 310 tons, 2.6 %
Armour: 1,783 tons, 15.0 %
- Belts: 496 tons, 4.2 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 226 tons, 1.9 %
- Armour Deck: 1,050 tons, 8.9 %
- Conning Tower: 11 tons, 0.1 %
Machinery: 2,300 tons, 19.4 %
Hull, fittings & equipment: 5,386 tons, 45.4 %
Fuel, ammunition & stores: 1,955 tons, 16.5 %
Miscellaneous weights: 130 tons, 1.1 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
20,258 lbs / 9,189 Kg = 79.1 x 8.0 " / 203 mm shells or 2.2 torpedoes
Stability (Unstable if below 1.00): 1.19
Metacentric height 3.9 ft / 1.2 m
Roll period: 14.6 seconds
Steadiness - As gun platform (Average = 50 %): 69 %
- Recoil effect (Restricted arc if above 1.00): 0.63
Seaboat quality (Average = 1.00): 1.40
Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.525
Length to Beam Ratio: 8.94 : 1
'Natural speed' for length: 24.70 kts
Power going to wave formation at top speed: 56 %
Trim (Max stability = 0, Max steadiness = 100): 49
Bow angle (Positive = bow angles forward): 10.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 32.00 ft / 9.75 m
- Forecastle (20 %): 26.00 ft / 7.92 m
- Mid (50 %): 24.00 ft / 7.32 m
- Quarterdeck (15 %): 24.00 ft / 7.32 m
- Stern: 24.00 ft / 7.32 m
- Average freeboard: 25.18 ft / 7.67 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 85.1 %
- Above water (accommodation/working, high = better): 201.7 %
Waterplane Area: 28,384 Square feet or 2,637 Square metres
Displacement factor (Displacement / loading): 132 %
Structure weight / hull surface area: 116 lbs/sq ft or 567 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.92
- Longitudinal: 2.00
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Good seaboat, rides out heavy weather easily
Refit Notes:
Replacement of 4in twins with 4,5in DP twin mounts
Replacement of 2pdr octuple mounts with 6pdr twin mounts
Addition of six twin 2pdr L/70 mounts
Removal of third aircraft
2 inch extra armour on main turret fronts and 1 inch on the roofs
1 inch extra armour on the main deck
New turbines and boilers
Two HACS Mk.IV
Radio-Location sets: one Type 284, one Type 285M, two Type 282M, one Type 283, one Type 276, one Type 271M, Passive Radio Intercept Type 293 (P,Q,M) and Passive RDF Intercept Type 294 and 294M
1948 Refit Notes
Removal of all aircraft and catapult
6pdr twin mounts updated with newer model
RDF and fire control systems updated
One Aerial Search Type 971 set
One Surface Search Type 970 set
One Height-Finder and Surface Search Type 277 set
Type 290 splash-spotting sets added to main director
Two Close-Range Blind Fire (CRBF) directors with Type 289 RDF
Passive Radio Intercept Type 293 series
Passive RDF intercept Type 297
Two RU-series jammers
The retired County Class cruiser HMS Suffolk will be rebuilt as a weapons trials ship with several new gun mounts. These will include a twin 5.5in mount based on the gun used in the Town Class cruiser-destroyers, a new 3in L/50 automatic gun for rapid-fire AA and anti-destroyer fire for vessels unable to carry the 4.5in gun or for major vessels which need additional AA firepower. The DNO also outlined a quadruple 6pdr AA using the same basic mount as the new sextuple 2pdr.
HMS Suffolk, Great Britain Weapons Trials Ship laid down 1924
Displacement:
9,761 t light; 10,052 t standard; 11,539 t normal; 12,729 t full load
Dimensions: Length overall / water x beam x draught
581.19 ft / 570.00 ft x 60.00 ft x 22.71 ft (normal load)
177.15 m / 173.74 m x 18.29 m x 6.92 m
Armament:
2 - 5.50" / 140 mm guns (1x2 guns), 80.00lbs / 36.29kg shells, 1945 Model
Automatic rapid fire guns in a deck mount with hoist
on centreline forward
2 - 4.50" / 114 mm guns (1x2 guns), 45.00lbs / 20.41kg shells, 1949 Model
Automatic rapid fire guns in a deck mount with hoist
on centreline aft
2 - 3.00" / 76.2 mm guns (1x2 guns), 12.50lbs / 5.67kg shells, 1950 Model
Automatic rapid fire guns in a deck mount with hoist
on centreline aft, all raised guns - superfiring
6 - 1.57" / 40.0 mm guns (1x6 guns), 2.00lbs / 0.91kg shells, 1947 Model
Anti-aircraft guns in deck mount
on centreline forward, all raised guns - superfiring
4 - 2.24" / 57.0 mm guns (1x4 guns), 6.00lbs / 2.72kg shells, 1950 Model
Anti-aircraft guns in deck mount
on side amidships, all raised guns
Weight of broadside 311 lbs / 141 kg
Shells per gun, main battery: 300
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 4.50" / 114 mm 405.00 ft / 123.44 m 9.30 ft / 2.83 m
Ends: Unarmoured
Main Belt covers 109 % of normal length
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.50" / 38 mm 1.00" / 25 mm 3.00" / 76 mm
2nd: 1.00" / 25 mm 1.00" / 25 mm 3.00" / 76 mm
3rd: 1.00" / 25 mm 1.00" / 25 mm 3.00" / 76 mm
4th: 1.00" / 25 mm 1.00" / 25 mm -
5th: 1.00" / 25 mm 1.00" / 25 mm -
- Armour deck: 2.00" / 51 mm
Machinery:
Oil fired boilers, steam turbines,
Geared drive, 4 shafts, 95,294 shp / 71,089 Kw = 32.00 kts
Range 10,100nm at 15.00 kts
Bunker at max displacement = 2,678 tons
Complement:
556 - 723
Cost:
£2.536 million / $10.145 million
Distribution of weights at normal displacement:
Armament: 47 tons, 0.4 %
Armour: 1,586 tons, 13.7 %
- Belts: 699 tons, 6.1 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 28 tons, 0.2 %
- Armour Deck: 859 tons, 7.4 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 3,139 tons, 27.2 %
Hull, fittings & equipment: 4,490 tons, 38.9 %
Fuel, ammunition & stores: 1,778 tons, 15.4 %
Miscellaneous weights: 500 tons, 4.3 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
14,254 lbs / 6,465 Kg = 171.3 x 5.5 " / 140 mm shells or 1.6 torpedoes
Stability (Unstable if below 1.00): 1.23
Metacentric height 3.4 ft / 1.0 m
Roll period: 13.7 seconds
Steadiness - As gun platform (Average = 50 %): 61 %
- Recoil effect (Restricted arc if above 1.00): 0.07
Seaboat quality (Average = 1.00): 1.10
Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.520
Length to Beam Ratio: 9.50 : 1
'Natural speed' for length: 23.87 kts
Power going to wave formation at top speed: 59 %
Trim (Max stability = 0, Max steadiness = 100): 55
Bow angle (Positive = bow angles forward): 25.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 24.00 ft / 7.32 m
- Forecastle (20 %): 23.00 ft / 7.01 m
- Mid (50 %): 20.00 ft / 6.10 m
- Quarterdeck (15 %): 18.00 ft / 5.49 m
- Stern: 18.00 ft / 5.49 m
- Average freeboard: 20.48 ft / 6.24 m
Ship tends to be wet forward
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 96.9 %
- Above water (accommodation/working, high = better): 160.2 %
Waterplane Area: 23,209 Square feet or 2,156 Square metres
Displacement factor (Displacement / loading): 132 %
Structure weight / hull surface area: 116 lbs/sq ft or 565 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 1.21
- Longitudinal: 1.92
- Overall: 1.27
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Weapons Trials Rebuild
Removal of all previous armament and electronics
Refurbishment of internal fittings
Reconstructed bridge and forward superstructure
Weapons Fit
'A' Position: twin 5.5in automatic mount (cancelled 6in auto turret with Canadian Vickers 5.5in)
'B' Position: sextuple 40mm mount (improved model)
'X' Position: twin 3in L/70 (experimental new gun and mount)
'Y' Position: twin 4.5in (new lighter mount)
'S1' Position: quadruple 57mm (6pdr) (experimental mount)
Electronics Fit
Two Surface Search Type 970
One Target Indication Type 975
One Height-Finding and Surface Search Type 977
One Prototype LRS.1 director with two Type 901
One Prototype MRS.3 director with Type 903
One Mk. VI director with two Type 288 with Tallboy console and Flyplane table
Two CRBF directors with Type 289
VHF Direction Finder Type 295Q