A few new types are planned, but some are still being tinkered with. So just one for the time being:
The two Patna class cruisers are intended to provide the Talwar class carriers with additional protection against aircraft.
The main battery is dual-purpose in the same sense as the historical Fubuki class destroyer's guns - elevating up to seventy degrees. Reasonable light AA is also provided.
The other notable change is the adoption of splinter protection for the torpedo banks. This is a consequence of the loss of SR Male some months back. Some witnesses claim that the catastrophic explosion which destroyed the ship originated in her portside torpedo carriage, and not the wing 21 cm turret. Given that the actual hit which triggered the loss was somewhat forward of this area, it has been supposed that flying debris somehow initiated the loss. The protection installed here may prove to be a new standard for Indian cruisers.
Two aircraft are provided as usual.
A fair weight reserve has been provided for this class. This is not only for possible additional light AA but also for potential modifications to the main battery. The BNS is aware of the development and potential for radar, but has no operational model to actually install at this time. Still, the class has weight set aside for it, and space has been set aside on the foremast for one.
Although the ship could have been designed around a hull strength of 0.9, the additional hull strength was deemed desirable in case operations brought the ship into cyclone paths.
Patna & Ludhiana, laid down 1934
Displacement:
5,736 t light; 5,985 t standard; 7,182 t normal; 8,140 t full load
Dimensions: Length overall / water x beam x draught
566.05 ft / 547.90 ft x 53.31 ft x 20.01 ft (normal load)
172.53 m / 167.00 m x 16.25 m x 6.10 m
Armament:
12 - 4.92" / 125 mm guns (6x2 guns), 59.59lbs / 27.03kg shells, 1934 Model
Dual purpose guns in deck mounts with hoists
on centreline ends, evenly spread, 4 raised mounts - superfiring
16 - 1.38" / 35.0 mm guns (8x2 guns), 1.31lbs / 0.59kg shells, 1934 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, 4 raised mounts
16 - 0.59" / 15.0 mm guns (4x4 guns), 0.10lbs / 0.05kg shells, 1934 Model
Machine guns in deck mounts
on side, all aft, all raised mounts - superfiring
Weight of broadside 738 lbs / 335 kg
Shells per gun, main battery: 250
10 - 21.7" / 550 mm above water torpedoes
Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 1.18" / 30 mm 356.14 ft / 108.55 m 8.86 ft / 2.70 m
Ends: Unarmoured
Upper: 1.18" / 30 mm 39.37 ft / 12.00 m 8.01 ft / 2.44 m
Main Belt covers 100 % of normal length
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.18" / 30 mm 0.79" / 20 mm 1.18" / 30 mm
3rd: 0.79" / 20 mm - -
4th: 0.79" / 20 mm - -
- Armour deck: 1.57" / 40 mm, Conning tower: 1.18" / 30 mm
Miscellaneous Weight:
-75 t: Two aircraft and a catapult
-40 t: Armor plating above torpedo carriages
-75 t: Weight reserve
Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 65,684 shp / 49,000 Kw = 32.85 kts
Range 20,000nm at 12.00 kts (Bunkerage = 2,155 tons)
Complement:
389 - 507
Cost:
£2.665 million / $10.658 million
Distribution of weights at normal displacement:
Armament: 92 tons, 1.3 %
Armour: 793 tons, 11.0 %
- Belts: 186 tons, 2.6 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 43 tons, 0.6 %
- Armour Deck: 555 tons, 7.7 %
- Conning Tower: 9 tons, 0.1 %
Machinery: 1,890 tons, 26.3 %
Hull, fittings & equipment: 2,771 tons, 38.6 %
Fuel, ammunition & stores: 1,446 tons, 20.1 %
Miscellaneous weights: 190 tons, 2.6 %
Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
9,310 lbs / 4,223 Kg = 156.2 x 4.9 " / 125 mm shells or 1.4 torpedoes
Stability (Unstable if below 1.00): 1.19
Metacentric height 2.7 ft / 0.8 m
Roll period: 13.7 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.33
Seaboat quality (Average = 1.00): 1.19
Hull form characteristics:
Hull has a flush deck
and transom stern
Block coefficient: 0.430
Length to Beam Ratio: 10.28 : 1
'Natural speed' for length: 26.89 kts
Power going to wave formation at top speed: 56 %
Trim (Max stability = 0, Max steadiness = 100): 59
Bow angle (Positive = bow angles forward): 30.00 degrees
Stern overhang: 3.28 ft / 1.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 25.75 ft / 7.85 m
- Forecastle (20 %): 18.04 ft / 5.50 m
- Mid (50 %): 18.04 ft / 5.50 m
- Quarterdeck (15 %): 18.04 ft / 5.50 m
- Stern: 18.04 ft / 5.50 m
- Average freeboard: 18.66 ft / 5.69 m
Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 99.2 %
- Above water (accommodation/working, high = better): 126.1 %
Waterplane Area: 19,046 Square feet or 1,769 Square metres
Displacement factor (Displacement / loading): 131 %
Structure weight / hull surface area: 87 lbs/sq ft or 423 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.94
- Longitudinal: 1.63
- Overall: 1.00
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is excellent
Ship has slow, easy roll, a good, steady gun platform