Escort Cruisers - Big or Small ?

[mentat]

Have been looking at Escort Cruiser design recently

Usually I think in terms of:

1. Wanting a decent number (6-8 in the Battle Fleet) + keeping them small + focussed on being capable vs. TBD + Flotilla Leader/smaller CL type attacks
2. Good all round protection - but extensive rather than thick belt
3. Reasonable speed - but no need to be in Pursuit mode - so 30 knots and reasonable bunker size

But for change I thought I would expore idea of a hi-lo mix - and see what a beefier Escort Cruiser might look like - still with Mission to screen and defend against Light forces attacking the Battleline - but good vs. most CLs too

These are the 2 contrasting designs - and I rather like the beefier one - seems to have good all round combat capability - bit like a RN Southampton class - but with more oomph

- any views anybody??


   Escort Cruiser Standard:

Sentinel,  BAE Fleet Escort Cruiser (Small) laid down 1918

Displacement:
   7,564 t light; 7,856 t standard; 8,929 t normal; 9,787 t full load

Dimensions: Length overall / water x beam x draught
   529.00 ft / 525.00 ft x 58.50 ft x 18.50 ft (normal load)
   161.24 m / 160.02 m x 17.83 m  x 5.64 m

Armament:
      8 - 5.51" / 140 mm guns (4x2 guns), 83.72lbs / 37.98kg shells, 1918 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, evenly spread, 2 raised mounts - superfiring
      4 - 3.50" / 88.9 mm guns in single mounts, 21.50lbs / 9.75kg shells, 1918 Model
     Anti-aircraft guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
      32 - 1.00" / 25.4 mm guns (8x4 guns), 0.50lbs / 0.23kg shells, 1918 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 772 lbs / 350 kg
   Shells per gun, main battery: 250
   8 - 22.0" / 558.8 mm above water torpedoes

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   3.50" / 89 mm   355.00 ft / 108.20 m   12.00 ft / 3.66 m
   Ends:   Unarmoured
   Upper:   3.00" / 76 mm   200.00 ft / 60.96 m   8.00 ft / 2.44 m
     Main Belt covers 104 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   3.00" / 76 mm   2.00" / 51 mm      3.00" / 76 mm
   3rd:   1.00" / 25 mm   0.80" / 20 mm            -

   - Armour deck: 1.80" / 46 mm, Conning tower: 4.00" / 102 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 4 shafts, 66,377 shp / 49,517 Kw = 30.00 kts
   Range 7,500nm at 15.00 kts
   Bunker at max displacement = 1,931 tons

Complement:
   459 - 597

Cost:
   £1.362 million / $5.448 million

Distribution of weights at normal displacement:
   Armament: 96 tons, 1.1 %
   Armour: 1,800 tons, 20.2 %
      - Belts: 849 tons, 9.5 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 201 tons, 2.2 %
      - Armour Deck: 714 tons, 8.0 %
      - Conning Tower: 37 tons, 0.4 %
   Machinery: 2,395 tons, 26.8 %
   Hull, fittings & equipment: 2,973 tons, 33.3 %
   Fuel, ammunition & stores: 1,364 tons, 15.3 %
   Miscellaneous weights: 300 tons, 3.4 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     10,400 lbs / 4,717 Kg = 124.2 x 5.5 " / 140 mm shells or 1.5 torpedoes
   Stability (Unstable if below 1.00): 1.12
   Metacentric height 2.8 ft / 0.8 m
   Roll period: 14.8 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.24
   Seaboat quality  (Average = 1.00): 1.04

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.550
   Length to Beam Ratio: 8.97 : 1
   'Natural speed' for length: 22.91 kts
   Power going to wave formation at top speed: 59 %
   Trim (Max stability = 0, Max steadiness = 100): 68
   Bow angle (Positive = bow angles forward): 0.00 degrees
   Stern overhang: 4.00 ft / 1.22 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      26.00 ft / 7.92 m
      - Forecastle (20 %):   22.00 ft / 6.71 m
      - Mid (50 %):      22.00 ft / 6.71 m (14.00 ft / 4.27 m aft of break)
      - Quarterdeck (15 %):   14.00 ft / 4.27 m
      - Stern:      15.00 ft / 4.57 m
      - Average freeboard:   18.40 ft / 5.61 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 100.0 %
      - Above water (accommodation/working, high = better): 126.4 %
   Waterplane Area: 21,434 Square feet or 1,991 Square metres
   Displacement factor (Displacement / loading): 117 %
   Structure weight / hull surface area: 90 lbs/sq ft or 438 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.97
      - Longitudinal: 1.29
      - 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


And here's the Beefier one - seems woth the extra and I'd love to see a Broadside in action  ;D

Devastation, BAE Fleet Escort Cruiser laid down 1918

Displacement:
   10,206 t light; 10,819 t standard; 12,197 t normal; 13,300 t full load

Dimensions: Length overall / water x beam x draught
   589.00 ft / 585.00 ft x 65.00 ft x 20.60 ft (normal load)
   179.53 m / 178.31 m x 19.81 m  x 6.28 m

Armament:
      12 - 6.00" / 152 mm guns (4x3 guns), 115.00lbs / 52.16kg shells, 1918 Model
     Quick firing guns in turrets (on barbettes)
     on centreline ends, evenly spread, 2 raised mounts - superfiring
      8 - 6.00" / 152 mm guns in single mounts, 115.00lbs / 52.16kg shells, 1918 Model
     Quick firing guns in deck mounts with hoists
     on side, all amidships
      6 - 3.50" / 88.9 mm guns in single mounts, 21.50lbs / 9.75kg shells, 1918 Model
     Anti-aircraft guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
      32 - 1.00" / 25.4 mm guns (8x4 guns), 0.50lbs / 0.23kg shells, 1918 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 2,445 lbs / 1,109 kg
   Shells per gun, main battery: 250
   8 - 22.0" / 558.8 mm above water torpedoes

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   4.00" / 102 mm   367.00 ft / 111.86 m   12.00 ft / 3.66 m
   Ends:   Unarmoured
   Upper:   3.50" / 89 mm   200.00 ft / 60.96 m   8.00 ft / 2.44 m
     Main Belt covers 97 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   4.00" / 102 mm   2.50" / 64 mm      4.00" / 102 mm
   2nd:   3.00" / 76 mm   2.00" / 51 mm      4.00" / 102 mm
   3rd:   1.00" / 25 mm   0.80" / 20 mm            -

   - Armour deck: 2.00" / 51 mm, Conning tower: 5.00" / 127 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 4 shafts, 76,642 shp / 57,175 Kw = 30.00 kts
   Range 8,000nm at 15.00 kts
   Bunker at max displacement = 2,482 tons

Complement:
   579 - 754

Cost:
   £1.973 million / $7.890 million

Distribution of weights at normal displacement:
   Armament: 288 tons, 2.4 %
   Armour: 2,511 tons, 20.6 %
      - Belts: 1,015 tons, 8.3 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 462 tons, 3.8 %
      - Armour Deck: 977 tons, 8.0 %
      - Conning Tower: 57 tons, 0.5 %
   Machinery: 2,765 tons, 22.7 %
   Hull, fittings & equipment: 4,342 tons, 35.6 %
   Fuel, ammunition & stores: 1,991 tons, 16.3 %
   Miscellaneous weights: 300 tons, 2.5 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     13,824 lbs / 6,270 Kg = 128.0 x 6.0 " / 152 mm shells or 1.7 torpedoes
   Stability (Unstable if below 1.00): 1.09
   Metacentric height 3.1 ft / 0.9 m
   Roll period: 15.6 seconds
   Steadiness   - As gun platform (Average = 50 %): 70 %
         - Recoil effect (Restricted arc if above 1.00): 0.50
   Seaboat quality  (Average = 1.00): 1.04

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.545
   Length to Beam Ratio: 9.00 : 1
   'Natural speed' for length: 24.19 kts
   Power going to wave formation at top speed: 56 %
   Trim (Max stability = 0, Max steadiness = 100): 67
   Bow angle (Positive = bow angles forward): 0.00 degrees
   Stern overhang: 4.00 ft / 1.22 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      26.00 ft / 7.92 m
      - Forecastle (20 %):   22.00 ft / 6.71 m
      - Mid (50 %):      22.00 ft / 6.71 m (14.00 ft / 4.27 m aft of break)
      - Quarterdeck (15 %):   14.00 ft / 4.27 m
      - Stern:      15.00 ft / 4.57 m
      - Average freeboard:   18.40 ft / 5.61 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 96.4 %
      - Above water (accommodation/working, high = better): 129.3 %
   Waterplane Area: 26,413 Square feet or 2,454 Square metres
   Displacement factor (Displacement / loading): 115 %
   Structure weight / hull surface area: 109 lbs/sq ft or 533 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.98
      - Longitudinal: 1.18
      - 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

[Sachmle]

I'd tend to agree that the larger one is more bang for your buck. It would be ~2 large vs ~3 small (20412 vs 22692) weight wise, and I think 2 of the big ones would do much more damage than 3 of the small ones with 12 more larger guns. Only thing I'd probably do is ditch the upper belt, use the weight to add more speed and put the beam 6" in 4 twins instead of 8 singles, frees up more room. As for 1918, I'd cut the 3.5s to 2 and ditch most of the 1" mgs, kinda overkill for AA in that time frame.

[Jefgte]

10206t with 20x6" is better.
The 6" are correct vs DD charge.

4 blocks with 2T2x6" could engage 4DDs -
8T2x6" in all.


Jef

[P3D]

I'd have only 12x6" with splitting fire between two targets (fore and aft turrets), I'd delete the 4 single mounts amidships. You don't have much of deck space either. You need to squeeze in 11 mounts AND one quad TT between the turrets Also make sure the ship does not exceed 557' length. Aim at a beam:draught ratio of somewhat below 3:1.

The smaller design should need the following changes:
a/ 557' length max
b/ 6 twin mounts with hoists, two "pyramids" fore and aft
c/ any unnecessary armor will make the ship less economical compared to the bigger one. Delete upper belt, cut deck armor to 1", any misc. weight over 150t is unnecessary. Should b around 7000t.

[mentat]

Thanks for interesting feedback guys

i agree the AA + MG armament is a bit too forward looking - as well as causing cramped amidships - both can be reduced - maybe 4 x 3.5 and 4 x 2  and 4 x 1  MGs - which are much smaller and can be mounted quite high up

I like the idea of a more economic version - within 556' would be good - but I am keen to keep the allround combat worthiness as is it's a bit of a Bulldog

So - i'm thinking - reduce length, trim UB to 3" and deck to 1.5", misc wt down to 200 - is this enough for good FC? - I want FC to handle 2 Targets for Main Battery

Main Battery remains as is - I like idea of 20 x 6" ! - and I am not sure about fitting twins on the beam on a 60' beam design

I'm thinking reduce TTs to two triples (it's not their main role) - and mount them a deck lower than weather deck - still 14' above SL

+ maybe reduce bunkerage by 10%

Any other thoughts welcome ...

[maddox]

It sounds that my Demarce IIIb's ain't a bad option then, simular function, simular size. Lighter armor, same speed, but that's age.

[Jefgte]

You say ...Escort Cruiser  ???

IMO, her job is to escort BBs, CVs, Tenders, Oilers, Cargos...
In a Fleet, engage enemy cruisers.

She is not made to escape or made fast runs on the oceans.
She is a watch-dog.

Escort Cruiser is
Slower than CL or AC.
Stronger & had better protection.

For exemple;  
AC 10000t - 4T2x8" - belt 4" - 32kts
EC 10000t - 4T2x9"2 - belt 4"5 - 27kts


Jef

[P3D]

27kts is slow, it won't give enough of speed difference vs. own battleline to act as a "perimeter guard" - i. e. 10-20nm distant from the battleline.
If they are closer to the battleline, you have to put the escorts in the battleline itself so they won't interfere with the battleline itself.
So just give the battleships enough 6" secondaries to deal with those pesky DDs (longer spotting range than 5").

[Jefgte]

ECs speed depend of the BBs speed in the Fleet.

For 21-22kts BBs Squadron- 25kts are correct.
For 24-25kts BBs squadron- 27-28kts are correct.

Interfere with the battleline... thats very good to confuse enemy fire.
Good also to outnumbers the enemy with semi heavy guns.


Jef  ;)

[mentat]

   mmmm - 'Escort Cruiser' - I think same name but different concept

    overall - I prefer to keep the heavy firepower in the Capital Ships

     having said that I think there can be a role for a heavier Cruiser in the Fleet line-up - I usually use term Combat Cruiser

    - something like: 13-14,000 tons - 12 x 220mm 12 x 130mm 5-6" Belt 30-31 knots good range

     - these are more flexible than a 27 knot Cruiser - as well as beefing up the Fleet screen vs. Cruiser attack - can also be deployed to support lighter ships for smaller operations or for independent operations

   - and I think this is about as big as Cruisers should get - after that better to build a Fast BB



   - this is a rough design I have to hand in this category to illustrate - but trim + Freeboard/Sea-keeping need a bit tweaking ...


Gunsmoke, BAE Combat Cruiser laid down 1918

Displacement:
   13,403 t light; 13,760 t standard; 14,846 t normal; 15,715 t full load

Dimensions: Length overall / water x beam x draught
   585.00 ft / 585.00 ft x 76.00 ft x 21.25 ft (normal load)
   178.31 m / 178.31 m x 23.16 m  x 6.48 m

Armament:
      12 - 8.66" / 220 mm guns (4 mounts), 325.00lbs / 147.42kg shells, 1918 Model
     Breech loading guns in turrets (on barbettes)
     on centreline ends, evenly spread, 2 raised mounts - superfiring
      12 - 5.12" / 130 mm guns (6x2 guns), 70.00lbs / 31.75kg shells, 1918 Model
     Breech loading guns in deck mounts with hoists
     on side, all amidships
      4 - 2.56" / 65.0 mm guns in single mounts, 8.50lbs / 3.86kg shells, 1918 Model
     Breech loading guns in deck mounts
     on side, evenly spread, all raised mounts
      24 - 1.00" / 25.4 mm guns (6x4 guns), 0.50lbs / 0.23kg shells, 1918 Model
     Breech loading guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 4,136 lbs / 1,876 kg
   Shells per gun, main battery: 150
   8 - 22.0" / 558.8 mm above water torpedoes

Armour:
   - Belts:      Width (max)   Length (avg)      Height (avg)
   Main:   4.50" / 114 mm   420.00 ft / 128.02 m   10.04 ft / 3.06 m
   Ends:   Unarmoured
     Main Belt covers 110 % of normal length

   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   5.00" / 127 mm   2.00" / 51 mm      4.25" / 108 mm
   2nd:   1.50" / 38 mm   0.70" / 18 mm      2.00" / 51 mm
   3rd:   0.80" / 20 mm   0.50" / 13 mm            -
   4th:   0.50" / 13 mm         -               -

   - Armour deck: 1.80" / 46 mm, Conning tower: 6.00" / 152 mm

Machinery:
   Oil fired boilers, steam turbines,
   Geared drive, 4 shafts, 102,596 shp / 76,537 Kw = 31.05 kts
   Range 9,000nm at 12.00 kts
   Bunker at max displacement = 1,955 tons

Complement:
   672 - 874

Cost:
   £2.814 million / $11.257 million

Distribution of weights at normal displacement:
   Armament: 512 tons, 3.5 %
   Armour: 2,568 tons, 17.3 %
      - Belts: 796 tons, 5.4 %
      - Torpedo bulkhead: 0 tons, 0.0 %
      - Armament: 660 tons, 4.4 %
      - Armour Deck: 1,033 tons, 7.0 %
      - Conning Tower: 78 tons, 0.5 %
   Machinery: 3,701 tons, 24.9 %
   Hull, fittings & equipment: 5,972 tons, 40.2 %
   Fuel, ammunition & stores: 1,743 tons, 11.7 %
   Miscellaneous weights: 350 tons, 2.4 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     14,855 lbs / 6,738 Kg = 45.7 x 8.7 " / 220 mm shells or 1.7 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 %): 50 %
         - Recoil effect (Restricted arc if above 1.00): 0.46
   Seaboat quality  (Average = 1.00): 0.93

Hull form characteristics:
   Hull has rise forward of midbreak
   Block coefficient: 0.550
   Length to Beam Ratio: 7.70 : 1
   'Natural speed' for length: 24.19 kts
   Power going to wave formation at top speed: 60 %
   Trim (Max stability = 0, Max steadiness = 100): 54
   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:      26.61 ft / 8.11 m
      - Forecastle (20 %):   24.93 ft / 7.60 m
      - Mid (50 %):      24.93 ft / 7.60 m (16.93 ft / 5.16 m aft of break)
      - Quarterdeck (15 %):   16.93 ft / 5.16 m
      - Stern:      16.93 ft / 5.16 m
      - Average freeboard:   21.06 ft / 6.42 m

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 110.3 %
      - Above water (accommodation/working, high = better): 156.7 %
   Waterplane Area: 31,028 Square feet or 2,883 Square metres
   Displacement factor (Displacement / loading): 103 %
   Structure weight / hull surface area: 132 lbs/sq ft or 645 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0.96
      - Longitudinal: 1.48
      - Overall: 1.00
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is excellent
   Poor seaboat, wet and uncomfortable, reduced performance in heavy weather

[P3D]

ECs speed depend of the BBs speed in the Fleet.

For 21-22kts BBs Squadron- 25kts are correct.
For 24-25kts BBs squadron- 27-28kts are correct.

Interfere with the battleline... thats very good to confuse enemy fire.
Good also to outnumbers the enemy with semi heavy guns.


Jef  ;)

If a 200m long "escort cruiser" is 2km broadside from a battleship, it blocks ~6 degree in the arc of fire. For opposing battleline at 20km it would block only 0.6 degrees. So it will interfere the own battleline more than the enemy - the enemy can shoot at the cruiser, killing it, while the blocked battleship will have its FC solution interrrupted every 3rd salvo.

4kts speed difference (~2m/s) means to overtake the battleline by 10km would take about 83 minutes, that's I'd hardly call adequate.

[P3D]

With 12x220mm main armament the ship should not need that heavy anti-surface secondaries.

   mmmm - 'Escort Cruiser' - I think same name but different concept

    overall - I prefer to keep the heavy firepower in the Capital Ships

     having said that I think there can be a role for a heavier Cruiser in the Fleet line-up - I usually use term Combat Cruiser

    - something like: 13-14,000 tons - 12 x 220mm 12 x 130mm 5-6" Belt 30-31 knots good range

     - these are more flexible than a 27 knot Cruiser - as well as beefing up the Fleet screen vs. Cruiser attack - can also be deployed to support lighter ships for smaller operations or for independent operations

   - and I think this is about as big as Cruisers should get - after that better to build a Fast BB
   - this is a rough design I have to hand in this category to illustrate - but trim + Freeboard/Sea-keeping need a bit tweaking ...

[mentat]

On the Secondaries - not sure 70 lb 130mm are heavy - more medium I'd say  ;D

I think is a good size vs. Destroyers + can make contribution vs CLs - and,  it's one of my favourite calibres ...

[P3D]

The 8-9" gun will have a ROF of 3-4 RPM, not much worse than the secondaries.
Honestly, I see no scenario where the secondaries would have any use. If it has to shoot on destroyers, they are too many and close and the main guns failed to do their job.

Put it this way, there was no heavy cruiser that had anti-surface secondaries.

[mentat]

Having a 2 layer defence makes sense to me, and the RoF I guess would be 2.5-3 for the 220mm and maybe 6-7 for the 130mm - so there is a difference

(British 5.5" from this era is claimed at 12 RPM - but I think 7-8 more likely)

The early S&G shipped 6 x 150mm as well as the main 8 x 210mm

  I think the 130mm is a practical fit for a secondary - but if others prefer without it's fine with me  :)