WesWorld

Since I dont really feel that I know enough about CV design I am looking for suggestions on redesigning this ship into a CVE/CVL

Length, 152.4 m x Beam, 15.2 m x Depth, 4.6 m
5158 tonnes normal displacement (4561 tonnes standard)

Main battery: 6 x 15.0-cm (3x2 deck mount w/hoist)
Secondary battery: 4 x 10.5-cm (1x2, 2x1)
AA battery: 6 x 3.5-cm (6x1)
Light battery: 8 x 1.5-cm (2x4)

Weight of broadside: 349 kg

8 TT, 55.0 cm (2x4)

Main belt, 7.5 cm; ends unarmored
Armor deck, average 3.5 cm
Conning tower, 7.5 cm

Battery armor:
Main, 5.0 cm shields / secondary, 3.0 cm
AA, 2.0 cm shields / light guns, 2.0 cm shields

Maximum speed for 30006 shaft kw = 29.02 knots
Approximate cruising radius, 9000 nm / 12 knots

Typical complement: 304-396


Estimated cost, $3.205 million (£801,000)

Remarks:

Oil firing.

Relative extent of belt armor, 110 percent of 'typical' coverage.

Ship has slow, easy roll; a good, steady gun platform.

Main deck secondary guns subject to being washed down
in a seaway.


Distribution of weights:
Percent
normal
displacement:

Armament ......................... 96 tonnes = 2 pct
Armor, total ..................... 814 tonnes = 16 pct

Belt 366 tonnes = 7 pct
Deck 389 tonnes = 8 pct
C.T. 19 tonnes = 0 pct
Armament 40 tonnes = 1 pct

Machinery ........................ 1474 tonnes = 29 pct
Hull and fittings; equipment ..... 1934 tonnes = 38 pct
Fuel, ammunition, stores ......... 764 tonnes = 15 pct
Miscellaneous weights ............ 75 tonnes = 1 pct
-----
5158 tonnes = 100 pct

Estimated metacentric height, 0.8 m

Displacement summary:

Light ship: 4394 tonnes
Standard displacement: 4561 tonnes
Normal service: 5158 tonnes
Full load: 5615 tonnes

Loading submergence 1428 tonnes/metre

+++++++++++++++++++++++++


Estimated overall survivability and seakeeping ability:

Relative margin of stability: 1.27

Shellfire needed to sink: 2533 kg = 54.1 x 15.0-cm shells
(Approximates weight of penetrating
shell hits needed to sink ship,
not counting critical hits)

Torpedoes needed to sink: 1.1
(Approximates number of 'typical'
torpedo hits needed to sink ship)

Relative steadiness as gun platform, 72 percent
(50 percent is 'average')

Relative rocking effect from firing to beam, 0.16

Relative quality as a seaboat: 1.14

+++++++++++++++++++++++++


Hull form characteristics:

Block coefficient: 0.48
Sharpness coefficient: 0.32
Hull speed coefficient 'M' = 8.85
'Natural speed' for length = 22.4 knots
Power going to wave formation
at top speed: 54 percent


Estimated hull characteristics and strength:

Relative underwater volume absorbed by
magazines and engineering spaces: 109 percent

Relative accommodation and working space: 110 percent


Displacement factor: 112 percent
(Displacement relative to loading factors)


Relative cross-sectional hull strength: 0.99
(Structure weight per square
metre of hull surface: 385 kg)

Relative longitudinal hull strength: 1.12
(for 4.60 m average freeboard;
freeboard adjustment +0.56 m)

Relative composite hull strength: 1.01

This from J Spencer gives an idea as to what the RN was thinking with escort carriers.

In December 1940, it was suggested that a simple conversion be made to a merchant ship. This would involve no more than adding a flight deck with a few arrester wires and would carry 6 fighters in a deck park (although suggested prewar - this was probably the first RN use of the scheme).
The resulting ship was HMS Audacity and the conversion took 6 months. The Admiralty were soon keen to search for more Audacity type conversions, plus the 4 Castle ships proposed prewar but was refused by cabinet. None the less and improved Audacity was drawn up with a lift and a hanger for 5 aircraft (4 stripped, 1 spread). The design was taken to the US were it was discovered that the US had already been working on a similar idea.
The British design featured;
Lift 42*20ft,
4-6 wires,
1 twin 4in
6 * twin 20mm
8* single 20mm
90 depth charges
10 torpedoes (surface raider)

The result of the US meeting would eventually lead to the RN leasing many US escort carriers. However at the same time the RN was also looking as 6 Castle class conversions, they would of had the following;
20,000 tons
Hanger for 6 swordfish + lift
6 fixed wing fighters in Deck park.

So poorly did it compare to the new US designs on half the tonnage that it was rejected.

The US lead/lease story is nicely covered elsewhere so there is no need to discuss it here. However even after lend/lease had been approved, there were serious concerns that many of the much needed ships may not arrive quickly enough (this became worse when the future building committee showed that the carrier shortage was far worse than feared). And so the RN continued to work on their own designs.

One idea to spring up was a proposal to design Merchant ship hulls ready for easy conversion to carriers. The draft requirements for this ships were as follows;
18kts diesel powered (6 months deep load),
15000nm at 15kts
550 by 75 ft flight deck
2 twin 4in
4 * predictor controlled pompoms
Hanger for 12 aircraft (with 6 non - folding)
As many 20mm as possible
Consideration was to be given to deck armour against dive bombing over mags and machinery with the best possible underwater sub division.

I can only say not bad for a Merchant ship. Not even a Colossus had most of that.

Naturally everyone felt that this was all a bit excessive! And three standards of conversion were developed instead called A B and C by February 1942.

A
20kts, 15,000 nm
25 Aircraft (16 in Hanger)
2 Lifts 45*35ft 15,000lbs
550 * 75ft flightdeck
6 wires 2 barriers
75,000 gallons of petrol
2 twin 4in
4 pompoms

B
18kts, 15,000 nm
15 Aircraft (12 in Hanger)
1 Lift 45*35ft 15,000lbs
500 * 70ft flightdeck
6 wires 2 barriers
50,000 gallons of petrol
2 twin 4in
4 pompoms

C
16.5kts, As much as possible nm
10 Aircraft (4 in Hanger)
1 Lift 42*20ft 10,000lbs
450 * 60ft flightdeck
4-5 wires 1 barriers
33,000 gallons of petrol
1 twin 4in
4 pompoms

All ships also carried Oerlikons, had an Island, asdic, accelerator and a crane.

Despite this early hopes in 1942 were for 6 more Audacity conversions. These were never carried out and the ships to be converted are unknown (if they ever were chosen).
However in march 1942 the decision was made to convert 2 AMCs and large merchant ships (Winchester Castle type) to escort carriers. The liner Georgic was on that list but was never converted. Had it been done she would have been rebuilt along the lines of Standard A.
Of the 2 AMCs only Pretoria Castle was converted (standard B) and after much re-thinking the resulting merchant ship conversions became Nairana and Vindex. It should be noted that at the dawn of 1942, the RN saw its escort carrier future as now being 30 US lead lease ships and 5 British conversions. By the end of the year The Future Building Committee had arrived and they revised this figure and it is here that the Escort carrier story ends - well almost...

One final idea from July 1942 was that the admiralty should start adding helicopter platforms to merchant ships. The helicopters would then carry small AS bombs and the US R-4 model was used for a trail. Sadly it failed to carry enough bombs to be of any value but this was not before the RN had tentatively order 500 R-5 models!

I'd say its probably a bit small to make an effective carrier but it should be able to carry some aircraft. I'd remove all guns mountings and superstructure. Add a small hangar and as much flight deck as possible. A single lift, probably not a catapult for the moment. Secure stowage for torpedoes or bombs might be a bit tricky. Add in some light AA around the edge of the flight deck.

So what would you consider the minimum length for a decent CVL to be?

Anyone that can make a SS of a CVE based on the posted ship?

Quoted

Originally posted by Vukovlad
Anyone that can make a SS of a CVE based on the posted ship?

I hadn't realised that Jutland is shorter than your ship!
Have a look!

The beam could be an issue, but is displacement your biggest concern?

My biggest concern is that I dont know how to SIM it...

The Jutland looks like a good Scout/training CV

Quoted

Originally posted by Vukovlad
My biggest concern is that I dont know how to SIM it...

The Jutland looks like a good Scout/training CV

Give me a day or two......

She would look a bit like Jutland, but with a smaller island.

(I guessed at the age of the original hull!)

Peto, Persia CVE laid down 1920 (Engine 1936)

Displacement:
5,094 t light; 5,224 t standard; 5,709 t normal; 6,097 t full load

Dimensions: Length overall / water x beam x draught
500.00 ft / 500.00 ft x 49.87 ft x 15.09 ft (normal load)
152.40 m / 152.40 m x 15.20 m x 4.60 m


Airgroup: 24 aircraft

Armament:
8 - 1.57" / 40.0 mm guns (4x2 guns), 1.95lbs / 0.89kg shells, 1920 Model
Anti-aircraft guns in deck mounts
on side ends, evenly spread, 2 raised mounts - superfiring
24 - 0.79" / 20.0 mm guns (12x2 guns), 0.24lbs / 0.11kg shells, 1920 Model
Anti-aircraft guns in deck mounts
on side, all amidships, 8 raised mounts - superfiring
Weight of broadside 21 lbs / 10 kg
Shells per gun, main battery: 1,000

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 2.95" / 75 mm 308.40 ft / 94.00 m 9.84 ft / 3.00 m
Ends: Unarmoured
Main Belt covers 95 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.98" / 25 mm 0.98" / 25 mm -
2nd: 0.98" / 25 mm 0.98" / 25 mm -

- Armour deck: 1.38" / 35 mm, Conning tower: 2.95" / 75 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 50,150 shp / 37,412 Kw = 30.00 kts
Range 9,000nm at 12.00 kts
Bunker at max displacement = 873 tons

Complement:
327 - 426

Cost:
£0.892 million / $3.569 million

Distribution of weights at normal displacement:
Armament: 3 tons, 0.0 %
Armour: 848 tons, 14.9 %
- Belts: 376 tons, 6.6 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 16 tons, 0.3 %
- Armour Deck: 436 tons, 7.6 %
- Conning Tower: 20 tons, 0.4 %
Machinery: 1,407 tons, 24.6 %
Hull, fittings & equipment: 2,136 tons, 37.4 %
Fuel, ammunition & stores: 615 tons, 10.8 %
Miscellaneous weights: 700 tons, 12.3 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
8,638 lbs / 3,918 Kg = 4,423.5 x 1.6 " / 40 mm shells or 1.3 torpedoes
Stability (Unstable if below 1.00): 1.18
Metacentric height 2.4 ft / 0.7 m
Roll period: 13.5 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.01
Seaboat quality (Average = 1.00): 1.67

Hull form characteristics:
Hull has rise forward of midbreak
Block coefficient: 0.531
Length to Beam Ratio: 10.03 : 1
'Natural speed' for length: 22.36 kts
Power going to wave formation at top speed: 57 %
Trim (Max stability = 0, Max steadiness = 100): 42
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: 32.81 ft / 10.00 m
- Forecastle (20 %): 32.81 ft / 10.00 m
- Mid (40 %): 32.81 ft / 10.00 m (13.12 ft / 4.00 m aft of break)
- Quarterdeck (15 %): 13.12 ft / 4.00 m
- Stern: 13.12 ft / 4.00 m
- Average freeboard: 21.00 ft / 6.40 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 94.5 %
- Above water (accommodation/working, high = better): 191.0 %
Waterplane Area: 17,095 Square feet or 1,588 Square metres
Displacement factor (Displacement / loading): 130 %
Structure weight / hull surface area: 69 lbs/sq ft or 335 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.91
- Longitudinal: 2.20
- 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
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Looks good how much would this cost? And could you switch the 20mm guns for 25mm guns? License fee?

I reckon a "Partial Reconstruction" or 50% of the total light tonnage, as you would be changing major amounts of superstructure, reforming the bow and changing all weapons.

Weapon changed as requested!

We can discuss fee if you want to use her!

Peto (a), Persia CVE laid down 1920 (Engine 1936)

Displacement:
5,108 t light; 5,244 t standard; 5,731 t normal; 6,120 t full load

Dimensions: Length overall / water x beam x draught
500.00 ft / 500.00 ft x 49.87 ft x 15.09 ft (normal load)
152.40 m / 152.40 m x 15.20 m x 4.60 m

Armament:
8 - 1.57" / 40.0 mm guns (4x2 guns), 1.95lbs / 0.88kg shells, 1920 Model
Anti-aircraft guns in deck mounts
on side ends, evenly spread, 2 raised mounts - superfiring
24 - 0.98" / 25.0 mm guns (12x2 guns), 0.48lbs / 0.22kg shells, 1920 Model
Anti-aircraft guns in deck mounts
on side, all amidships, 8 raised mounts - superfiring
Weight of broadside 27 lbs / 12 kg
Shells per gun, main battery: 1,000

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 2.95" / 75 mm 308.40 ft / 94.00 m 9.84 ft / 3.00 m
Ends: Unarmoured
Main Belt covers 95 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.98" / 25 mm 0.98" / 25 mm -
2nd: 0.98" / 25 mm 0.98" / 25 mm -

- Armour deck: 1.38" / 35 mm, Conning tower: 2.95" / 75 mm

Machinery:
Oil fired boilers, steam turbines,
Geared drive, 2 shafts, 50,317 shp / 37,536 Kw = 30.00 kts
Range 9,000nm at 12.00 kts
Bunker at max displacement = 875 tons

Complement:
329 - 428

Cost:
£0.896 million / $3.586 million

Distribution of weights at normal displacement:
Armament: 3 tons, 0.1 %
Armour: 852 tons, 14.9 %
- Belts: 376 tons, 6.6 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 18 tons, 0.3 %
- Armour Deck: 437 tons, 7.6 %
- Conning Tower: 20 tons, 0.4 %
Machinery: 1,412 tons, 24.6 %
Hull, fittings & equipment: 2,141 tons, 37.4 %
Fuel, ammunition & stores: 622 tons, 10.9 %
Miscellaneous weights: 700 tons, 12.2 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
8,659 lbs / 3,928 Kg = 4,434.2 x 1.6 " / 40 mm shells or 1.3 torpedoes
Stability (Unstable if below 1.00): 1.18
Metacentric height 2.4 ft / 0.7 m
Roll period: 13.5 seconds
Steadiness - As gun platform (Average = 50 %): 70 %
- Recoil effect (Restricted arc if above 1.00): 0.01
Seaboat quality (Average = 1.00): 1.66

Hull form characteristics:
Hull has rise forward of midbreak
Block coefficient: 0.533
Length to Beam Ratio: 10.03 : 1
'Natural speed' for length: 22.36 kts
Power going to wave formation at top speed: 57 %
Trim (Max stability = 0, Max steadiness = 100): 42
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: 32.81 ft / 10.00 m
- Forecastle (20 %): 32.81 ft / 10.00 m
- Mid (40 %): 32.81 ft / 10.00 m (13.12 ft / 4.00 m aft of break)
- Quarterdeck (15 %): 13.12 ft / 4.00 m
- Stern: 13.12 ft / 4.00 m
- Average freeboard: 21.00 ft / 6.40 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 94.5 %
- Above water (accommodation/working, high = better): 190.2 %
Waterplane Area: 17,127 Square feet or 1,591 Square metres
Displacement factor (Displacement / loading): 130 %
Structure weight / hull surface area: 69 lbs/sq ft or 336 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.91
- Longitudinal: 2.20
- 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
Excellent seaboat, comfortable, can fire her guns in the heaviest weather

Airgroup = 24 aircraft

Just one more thing, is there any reason not to put in a new engine?

If you make a 50% rebuild you essentially have to pay for the engine anyway, might as well get a new one. Saves weight and increases range, sometimes speed too.

So its stupid not to replace it

I wouldn't say stupid... I just wouldn't see any reason not to.

Perhaps the wrong word but the engine is "part" of the price for a partial rebuild.

Quoted

Originally posted by Vukovlad
Perhaps the wrong word but the engine is "part" of the price for a partial rebuild.

Correct.
If you were only replacing the engine it would be 50% anyway, so as you are paying that for "Major Suprestructure Changes" for flight deck etc., you may as well have a new engine.

Newer engines are smaller and lighter for a given speed, and they can have benefits in the SpringSharp that will allow a little wiggle room with other aspects of the ships design.

Thsi is actually the ship Persia will be using as a base for their CVE:

Light cruiser laid down 1919 (Engine 1928 )

Displacement:
4,567 t light; 4,670 t standard; 5,161 t normal; 5,553 t full load

Dimensions: Length overall / water x beam x draught
500.00 ft / 500.00 ft x 49.87 ft x 15.09 ft (normal load)
152.40 m / 152.40 m x 15.20 m x 4.60 m

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 2.95" / 75 mm 377.30 ft / 115.00 m 8.46 ft / 2.58 m
Ends: Unarmoured
Main Belt covers 116 % of normal length

- Armour deck: 1.38" / 35 mm, Conning tower: 2.95" / 75 mm

Machinery:
Oil fired boilers, steam turbines,
Direct drive, 4 shafts, 40,179 shp / 29,973 Kw = 29.02 kts
Range 9,000nm at 12.00 kts
Bunker at max displacement = 883 tons

Complement:
303 - 395

Cost:
£0.731 million / $2.923 million

Distribution of weights at normal displacement:
Armament: 0 tons, 0.0 %
Armour: 818 tons, 15.9 %
- Belts: 383 tons, 7.4 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 0 tons, 0.0 %
- Armour Deck: 416 tons, 8.1 %
- Conning Tower: 19 tons, 0.4 %
Machinery: 1,251 tons, 24.2 %
Hull, fittings & equipment: 1,798 tons, 34.8 %
Fuel, ammunition & stores: 594 tons, 11.5 %
Miscellaneous weights: 700 tons, 13.6 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
7,020 lbs / 3,184 Kg = 65.0 x 6 " / 152 mm shells or 1.3 torpedoes
Stability (Unstable if below 1.00): 1.12
Metacentric height 2.2 ft / 0.7 m
Roll period: 14.2 seconds
Steadiness - As gun platform (Average = 50 %): 74 %
- Recoil effect (Restricted arc if above 1.00): 0.00
Seaboat quality (Average = 1.00): 1.24

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.480
Length to Beam Ratio: 10.03 : 1
'Natural speed' for length: 22.36 kts
Power going to wave formation at top speed: 54 %
Trim (Max stability = 0, Max steadiness = 100): 60
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: 24.61 ft / 7.50 m
- Forecastle (20 %): 15.65 ft / 4.77 m
- Mid (50 %): 15.65 ft / 4.77 m
- Quarterdeck (10 %): 15.65 ft / 4.77 m
- Stern: 15.65 ft / 4.77 m
- Average freeboard: 16.37 ft / 4.99 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 93.9 %
- Above water (accommodation/working, high = better): 160.5 %
Waterplane Area: 16,318 Square feet or 1,516 Square metres
Displacement factor (Displacement / loading): 128 %
Structure weight / hull surface area: 70 lbs/sq ft or 342 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.99
- Longitudinal: 1.17
- Overall: 1.01
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
Good seaboat, rides out heavy weather easily

I posted the wrong Jaipur stats?

Quoted

Originally posted by Vukovlad
I posted the wrong Jaipur stats?

Yes. You posted the original ones. The ship is right now being used as a test bench and all their weapons are already removed.