How much speed is too much for a CVL?

[stevethecat]

I'm glad that this has triggered some debate and discussion. Unfortunately, all of my ongoing saves were mid 40's on, where the tech level has mitigated too much of the speed weight cost and ruled out any useful comparisons. Was waiting until the expansion to start a new campaign, but 'for science' has suggested otherwise this weekend.

[nimrod]

DOM, setting to patrol is good to know. I'll definitely be experimenting with it.

Stevethecat, any updates from this weekend's potential science experiment? If you've gained or reinforced any views, I would be interested in hearing about them.

[stevethecat]

Jul 13, 2021 13:54:08 GMT -6 nimrod said:

Stevethecat, any updates from this weekend's potential science experiment? If you've gained or reinforced any views, I would be interested in hearing about them.

Sorry for the delay, progress has been slowed by an unexpected war with the USA and France. Also the game is refusing to give me CVL tech, I have 55,000t Lion+ class Battleships running around coated in heavy Dual Purpose weapons, yet aircraft carriers currently don't exist. A lot of the other tech I have unlocked has made for a poor representation of the usual early game CVLs so I'm tempted to do a reset.

Best laid plans...

[stevethecat]

Finally, my game has unlocked CVLs!, actually it took 2 campaigns, the first attempt took so long that I had an unrepresentative amount of engine/hull tech making fast CVLs trivial rather than a compromise. So this is 1930 UK (still ~5 years later than I would have liked), all of the following ships feature 30 aircraft, 1" flight deck, 2" deck and 2.5" belt. Weaponry is 4x4" DP guns. Weights were balanced down to having 200 spare tonnes, my usual spare capacity for future upgrades.

I have included below the total cost, and airframes, of a fleet of each speed built to the same cost as 10x30 knot ships.

For those who run thinner skinned CVLs the weight is pretty much a constant at these hull levels so doesn't affect the results too much, you would save a few pennies though, maybe just about scrape enough cash for one more hull on the costs x10 fleet build comparison...


30 knots: 16,000t, 19 months, 2741 per month. Total: 52079. Hulls: 10 Total aircraft: 300

28 knots: 14,600t, 19 months, 2352 per month. Total: 44688. Hulls: 11.65 Total aircraft: 330

26 knots: 13,600t, 18 months, 2242 per month. Total: 40356. Hulls: 12.90 Total aircraft: 360

24 knots: 13,200t, 18 months, 2084 per month. Total: 36864. Hulls: 14.13 Total aircraft: 420

22 knots: 12,700t, 18 months, 1939 per month. Total: 34902. Hulls: 14.92 Total aircraft: 420

20 knots: 12,300t, 18 months, 1820 per month. Total: 32760. Hulls: 15.90 Total aircraft: 450

18 knots: 11,700t, 16 months, 1890 per month. Total: 30240. Hulls: 17.22 Total aircraft: 510 (Catapults required)

16 knots: 10,800t, 16 months, 1663 per month. Total: 26608. Hulls: 19.57 Total aircraft: 570 (Catapults required)


So a fleet of 10 30 knot CVLs will take 520790 out of your budget, and take 19 months to get ready. Dropping the speed down to 28 will net you 11 and a bit of change. You could get 12x26 knot CVLs for the same money, and *almost* enough for a 13th. A full 14x24 knot CVLs could be purchased. Dropping to 22knots does not gain you any more though, just some more change. 15x20knots can be purchased, and you could get 17x18 knot ships or a hefty 19x16 knotters. An easy win for the slow bois? Not quite, you can't operate a CVL that slow unless you have catapult tech, which I find comes frustratingly late, especially for the UK who invented the damn things.


Obviously, your tech levels will vary things, but the relevant ratios should remain. As an oddity, once you have catapults unlocked you can build a CVL that can only do 1 knot, and it would be a valid ship... You could build 21 of those!

As for me, in future games I'm going to give ~24 knot CVLs a go, a decent speed for keeping with my surface combatants and a pretty good airframe:cost ratio.

[nimrod]

Thanks for the info Stevethecat!

[dorn]

You calculate just a hull.

However to have whole picture, it should include all lifetime costs, so maintenance of ship and aicraft with some assumption how long that ship would be in service.

After that costs of speed is significantly lower as percentage of overall lifetime costs per aicraft.

[nimrod]

Dom,

I think Steve's data is really valuable and it reinforces my comfort with my usual 20-23 knots CVLs. I usually have slightly different designs - more DP guns and no flight deck armor - but his data shows the cost and deploy-able AC advantages of the slower ships. Steve's data is really good for looking at lost opportunity costs; those CVLs need escorts and you might also have a critical need for a BC or CA as well. Going cheap on the hulls to meet your AC requirements be it a need for 90 or 300 AC frees up money for the other ships your navy needs. 

You are correct on the lack of maintenance / life time costs; but I think there would have to be too many assumptions in costs for the hull and the AC for the numbers to be meaningful. If you are at war then costs change, if you are at peace then costs change, AF, MB, Reserve all change the cost along with overseas deployment; the only constant is the set cost for a given design and technology setup at the time of construction. If you are doing lifetime costs than one should also take into account survivability of the design. Doesn't the weight of AC increase as time goes on as well, if so how does one account for a ship that loses free tonnage as time goes on? I know the increase in AC weight doesn't affect cost, but it does affect ones options during a refit and that impacts lifetime costs.

Again you are correct Dom. I just don't have a good idea of how to properly do the lifetime calculations and or take into account the lost opportunity costs beyond looking at the initial hull cost. The lifetime numbers really need to be done on an individual game with the random tech advances, game or historical budgets, fleet size; or at a min. one would need to utilize a play style basis.

For example, in the early years I don't even look at AC costs only hull; as I normally place my CVs in reserve and MB the CVLs after a war. If I'm in the unsettled tech years - mid 20s through late 30's I often disband a lot of my squadrons as well; as the cost of maintaining unskilled squadrons of outdated air-frames isn't worth it for me. Usually I can see a war in sufficient time to get the ships into reserve or active fleet status and have operational squadrons on my handful of early carriers by the time the shooting starts.

Once I have fighter bombers and dive bombers I put those squadrons into the reserve pool while my numerous carriers are typically placed into reserve or MB depending on my CVL to CV ratios and what the political situation dictates for ready to deploy ships. There is a big difference in the time needed to outfit the squadrons of 3-4 early carriers (30-60 AC) than 8+ advanced carriers (80+ AC). Likewise once I get DP main gun armament and forward ASW mortar for the
DDs, I build a ton of them to a standard design; prior to those
technologies I tend to build smaller amounts of DD to fill specific needs
(AAA, ASW, TORP, etc.). So for lost opportunity costs its very tough to calculate a standard 1500 ton DD for me, while I do have a standard 2000-2500 ton DD.

[stevethecat]

Jul 23, 2021 1:00:50 GMT -6 dorn said:

You calculate just a hull.

However to have whole picture, it should include all lifetime costs, so maintenance of ship and aicraft with some assumption how long that ship would be in service.

After that costs of speed is significantly lower as percentage of overall lifetime costs per aicraft.

Maintenance is generally a proportion of building cost so ratios should hold on a hulls per cost basis, aircraft costs speak for themselves but for the hassle of a bit more micromanagement they can be as high or as low as each player wants via air base controls. You can afterall remove all aircraft from mothballed ships, just with the annoyance of an occasional warning message. So that comes down to the player's own doctrine of aircraft management. I tried to stick to fixed values rather than factors down to how a player manages their fleet. Also keep in mind that aircraft level effects their cost, so you would also need to factor in 'when' just as much as 'how many'.

How long they stay in service also comes down to the player, and how each war is going. I don't tend to scrap any CV/CVL, but rather bump them to colonial/TP once they get too old for frontline.

[dorn]

You are right, you never know what can happen. But it is about assumption. You can take one. You can take your asumption how you expect to use such ship.

Eg. 
I have 30 knots CVL built in 1933 for 35,107. She has maintenance costs of 188 and can have 32 aircraft.
So I can take assumption that such ship is expected to operate 20 years. She will be put in reserve included aicraft in peace and fully operational in a war. I can take some assumption that during 20 years I will have 2 wars, each 3 years long. 
So total peace time is 14 years, wartime 6 years.

Building costs: 35107 + about 2200 design costs (I do not remember exact amount)
Maintenance costs (CVL): 12 * 14 * 188 * 0.5 + 12 * 6 * 188 * 1.5 = 36,096
    (12 months * years * monthly costs * adjustment war/peace reserve)

Aicraft costs:  (number of months * years * maintenance costs of 1 aicraft * #of aircraft * ajd. peace / war) = 61,102
    war: 12 * 6 * 8 * 32 * 1.6 = 29,491
    peace: 12 * 14 * 8 * 32 * (0.7) * (1.5*0.7) = 31,611


So total lifetime expected costs for such a carrier is about 135k. So now you can compare how much you save by slowing down carrier and evaluate what is important for you, the costs down or faster carrier in battle.

Just notice the ration of designing and construction costs to overall lifetime costs of such carrier.

EDIT: corrected aicraft costs