Irish General Light Cruiser/ Costal Defence Ship

[snip]

This is a design I have been toying with for a wile. If any examples are built, they would be the largest ship in the Irish navy by 500 tons (light displacement). The goal with the design is to have an escort for the larger minelayers that has a good anti-DD armament that can also fight other cruisers of around the same weight class. The hull also has some minelaying ablities. Another consideration was a large amount of reserve and assignable weight to allow for modifications as needed. Hulls are scarce so modibilty and expansion room are going to be a requirement on any large ship. The layout is based on the Emerald class light cruisers of the Royal Navy.

Kerrianne Class, Irish Pocket Cruiser laid down 1920 (Engine 1912)

Displacement:
   3,000 t light; 3,146 t standard; 3,463 t normal; 3,717 t full load

Dimensions: Length overall / water x beam x draught
   320.00 ft / 310.00 ft x 50.00 ft x 14.00 ft (normal load)
   97.54 m / 94.49 m x 15.24 m  x 4.27 m

Armament:
      4 - 6.00" / 152 mm guns in single mounts, 100.00lbs / 45.36kg shells, 1920 Model
     Breech loading guns in deck mounts with hoists
     on centreline ends, evenly spread, 2 raised mounts - superfiring
      2 - 6.00" / 152 mm guns in single mounts, 100.00lbs / 45.36kg shells, 1920 Model
     Breech loading guns in deck mounts with hoists
     on side, all forward
      4 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1920 Model
     Quick firing guns in deck mounts
     on side, all amidships
      4 - 0.98" / 25.0 mm guns (2x2 guns), 0.48lbs / 0.22kg shells, 1920 Model
     Machine guns in deck mounts
     on side, all aft
      2 - 0.98" / 25.0 mm guns (1x2 guns), 0.48lbs / 0.22kg shells, 1920 Model
     Machine guns in deck mount
     on centreline amidships
   Weight of broadside 731 lbs / 332 kg
   Shells per gun, main battery: 172

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   4.00" / 102 mm   201.50 ft / 61.42 m   8.49 ft / 2.59 m
   Ends:   1.00" / 25 mm   108.48 ft / 33.06 m   8.49 ft / 2.59 m
   Upper:   2.00" / 51 mm   201.50 ft / 61.42 m   8.00 ft / 2.44 m
     Main Belt covers 100 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   3.00" / 76 mm   1.00" / 25 mm      3.00" / 76 mm
   2nd:   3.00" / 76 mm   1.00" / 25 mm      3.00" / 76 mm
   3rd:   1.00" / 25 mm         -               -
   4th:   0.50" / 13 mm         -               -
   5th:   0.50" / 13 mm         -               -

   - Armour deck: 1.50" / 38 mm, Conning tower: 5.00" / 127 mm

Machinery:
   Diesel Internal combustion motors,
   Direct drive, 2 shafts, 13,958 shp / 10,413 Kw = 22.00 kts
   Range 5,000nm at 12.00 kts
   Bunker at max displacement = 571 tons

Complement:
   225 - 293

Cost:
   £0.626 million / $2.503 million

Distribution of weights at normal displacement:
   Armament: 97 tons, 2.8 %
   Armour: 864 tons, 25.0 %
      - Belts: 475 tons, 13.7 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 62 tons, 1.8 %
      - Armour Deck: 303 tons, 8.7 %
      - Conning Tower: 25 tons, 0.7 %
   Machinery: 557 tons, 16.1 %
   Hull, fittings & equipment: 1,226 tons, 35.4 %
   Fuel, ammunition & stores: 463 tons, 13.4 %
   Miscellaneous weights: 256 tons, 7.4 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     5,400 lbs / 2,450 Kg = 50.0 x 6.0 " / 152 mm shells or 1.3 torpedoes
   Stability (Unstable if below 1.00): 1.21
   Metacentric height 2.5 ft / 0.8 m
   Roll period: 13.2 seconds
   Steadiness   - As gun platform (Average = 50 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.30
   Seaboat quality  (Average = 1.00): 1.08

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.559
   Length to Beam Ratio: 6.20 : 1
   'Natural speed' for length: 17.61 kts
   Power going to wave formation at top speed: 61 %
   Trim (Max stability = 0, Max steadiness = 100): 46
   Bow angle (Positive = bow angles forward): 20.22 degrees
   Stern overhang: 3.00 ft / 0.91 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      19.00 ft / 5.79 m
      - Forecastle (20 %):   16.00 ft / 4.88 m
      - Mid (65 %):      16.00 ft / 4.88 m (12.50 ft / 3.81 m aft of break)
      - Quarterdeck (15 %):   12.50 ft / 3.81 m
      - Stern:      12.50 ft / 3.81 m
      - Average freeboard:   15.02 ft / 4.58 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 82.8 %
      - Above water (accommodation/working, high = better): 137.8 %
   Waterplane Area: 10,904 Square feet or 1,013 Square metres
   Displacement factor (Displacement / loading): 115 %
   Structure weight / hull surface area: 76 lbs/sq ft or 370 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.91
      - Longitudinal: 2.39
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is excellent
   Room for accommodation and workspaces is excellent

100 tons Fire controle
50 tons mines
25 tons long range wireless
25 tons flag facilities
25 tons nightfighting equipment
15 tons medical facilities
10 tons short range wireless (redundant)
6 tons construction reserve

Here is a line drawing


Thanks to Carthaginian for his help with this.

[Carthaginian]

A nice little deterrent ship.
Armor is good, speed is fine for a CDS, and it has good firing arcs overall.

I might think about a few small modifications, though:
1.) The superstructure: YUCK! That gentle slope aft of the bridge has got to go. ;)
Just let the stacks protrude and end the bridge structure where the bridge ends... cut down on 'topweight.'
2.) I'd think about making that forward 4" gun raised in order to get a clear field of fire forward over the 6" mount.
As it's placed right now, it's only got a very limited field of fire. You've got a lot of tonnage on this ship for things you don't really have enough space to put aboard. Use some of it for this small change. Drop the 10 tons for the redundant SR Marconi... that is too much redundancy. :)
3.) Torpedoes- nothing in the nautical world says 'keep your distance' like a spread of torpedoes.
And as this ship will likely be doing most of it's work near shore, close to friendly mine fields and in places where deeper draft ships might not be able to maneuver so well... well, the space to avoid those torps might not be available without exposing your ships to even greater dangers. :D
A triple launcher on the fantail would work WONDERS... and can be purchased for a pittance at your local Confederate Embassy.


It's a good ship for Ireland, I think... perhaps not as 'perfect' as it could be, but still she'd be a tough little nut for many N-verse cruisers to crack and is a very unique design.

[snip]

1. Why is the downward slope ugly? I think it looks good...
2. Now that I think about it that might not be a bad idea. would have to move the other mount further aft but it would work.
3. Now its looking like there would be a very small number of these ships (ie 1 maybe 2). They would also have there own escorts that have torpedo launchers. And dont forget about those little things called subs...I have a few  :)

[TexanCowboy]

I'm still confused what the purpose of this ship is to be. The gun battery of the ship is fairly weak for a CDS, and it doesn't seem like it would be much of a deterrent.

A modified version of this CSA design would seem to be a more effective deterrent.

laid down 1919 (Engine 1916)

Displacement:
  3,580 t light; 3,834 t standard; 4,287 t normal; 4,649 t full load

Dimensions: Length overall / water x beam x draught
  315.00 ft / 315.00 ft x 62.00 ft x 12.00 ft (normal load)
  96.01 m / 96.01 m x 18.90 m  x 3.66 m

Armament:
     6 - 7.50" / 191 mm guns (3x2 guns), 200.00lbs / 90.72kg shells, 1919 Model
    Breech loading guns in turrets (on barbettes)
    on centreline ends, majority aft, 1 raised mount aft - superfiring
     1 - 1.58" / 40.1 mm guns in single mounts, 2.00lbs / 0.91kg shells, 1919 Model
    Anti-aircraft gun in deck mount
    on centreline amidships, 1 raised gun
     8 - 1.00" / 25.4 mm guns (4x2 guns), 0.50lbs / 0.23kg shells, 1919 Model
    Machine guns in deck mounts
    on side, all amidships, all raised mounts - superfiring
  Weight of broadside 1,206 lbs / 547 kg
  Shells per gun, main battery: 250

Armour:
  - Belts:      Width (max)   Length (avg)      Height (avg)
  Main:   4.00" / 102 mm   200.00 ft / 60.96 m   16.00 ft / 4.88 m
  Ends:   Unarmoured
    Main Belt covers 98 % of normal length

  - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
  Main:   4.00" / 102 mm   2.00" / 51 mm      3.00" / 76 mm

  - Armour deck: 1.00" / 25 mm, Conning tower: 3.00" / 76 mm

Machinery:
  Diesel Internal combustion motors,
  Geared drive, 4 shafts, 12,000 shp / 8,952 Kw = 20.10 kts
  Range 7,000nm at 12.00 kts
  Bunker at max displacement = 815 tons

Complement:
  264 - 344

Cost:
  £0.701 million / $2.805 million

Distribution of weights at normal displacement:
  Armament: 159 tons, 3.7 %
  Armour: 1,038 tons, 24.2 %
     - Belts: 581 tons, 13.6 %
     - Torpedo bulkhead: 0 tons, 0.0 %
     - Armament: 165 tons, 3.9 %
     - Armour Deck: 274 tons, 6.4 %
     - Conning Tower: 17 tons, 0.4 %
  Machinery: 447 tons, 10.4 %
  Hull, fittings & equipment: 1,737 tons, 40.5 %
  Fuel, ammunition & stores: 707 tons, 16.5 %
  Miscellaneous weights: 200 tons, 4.7 %

Overall survivability and seakeeping ability:
  Survivability (Non-critical penetrating hits needed to sink ship):
    8,114 lbs / 3,681 Kg = 38.5 x 7.5 " / 191 mm shells or 1.9 torpedoes
  Stability (Unstable if below 1.00): 1.16
  Metacentric height 3.2 ft / 1.0 m
  Roll period: 14.5 seconds
  Steadiness   - As gun platform (Average = 50 %): 70 %
        - Recoil effect (Restricted arc if above 1.00): 0.32
  Seaboat quality  (Average = 1.00): 1.00

Hull form characteristics:
  Hull has rise forward of midbreak
  Block coefficient: 0.640
  Length to Beam Ratio: 5.08 : 1
  'Natural speed' for length: 17.75 kts
  Power going to wave formation at top speed: 58 %
  Trim (Max stability = 0, Max steadiness = 100): 70
  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:      20.00 ft / 6.10 m
     - Forecastle (15 %):   17.00 ft / 5.18 m
     - Mid (70 %):      16.00 ft / 4.88 m (8.00 ft / 2.44 m aft of break)
     - Quarterdeck (15 %):   8.50 ft / 2.59 m
     - Stern:      9.00 ft / 2.74 m
     - Average freeboard:   14.36 ft / 4.38 m

Ship space, strength and comments:
  Space   - Hull below water (magazines/engines, low = better): 69.8 %
     - Above water (accommodation/working, high = better): 157.6 %
  Waterplane Area: 14,827 Square feet or 1,378 Square metres
  Displacement factor (Displacement / loading): 126 %
  Structure weight / hull surface area: 91 lbs/sq ft or 444 Kg/sq metre
  Hull strength (Relative):
     - Cross-sectional: 0.92
     - Longitudinal: 2.14
     - 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

[snip]

The idea is more of an anti-DD escort for the minelayers. There is one class that has 8 inch guns that could also serve in a CDS role. The other one only has 4 inch guns and is much faster. I also need a ship that can be very multi-purpose due to the fact that I will only have a small number of large hulls.

[Carthaginian]

*snip* (no pun intended)

I'm still confused what the purpose of this ship is to be. The gun battery of the ship is fairly weak for a CDS, and it doesn't seem like it would be much of a deterrent.

A modified version of this CSA design would seem to be a more effective deterrent.

*snip*

TC,

Against most light cruisers in N-verse, Snip's little ship would be a rather annoying vessel. Not something to be terrified of, but a ship that can cause real damage nonetheless. His rather thick deck and belt should give a good immunity against most 5.5-6.1" armed ships, many of whom would have only speed and maneuverability as advantages. In the enclosed spaces of the Irish Sea and with land-based aircraft and mine barrages in support, the ship becomes a VERY challenging opponent.

Also, for Ireland, that 500 ton difference means another destroyer-sized hull in the water.

[snip]

and 3 TT with the current 500 ton DDish design  ;D