Very simply, late classing is the fact of not classing a sailor on time, the objective being a higher growth in a secondary stat in exchange for a lower growth in a primary stat.

One very important example is IJN AA gunners: normal classings increase the "primary stat" AAW (that is deactivated for any sailors) and decrease / stagnate reload - the latter being the one most important stat for using AA guns. Thus the solution is to leave IJN AA sailors on the classing "armament sailor" for as long as possible (at least level 80...)

That is late-classing.

example //mentioned stats may not be correct now.//

you want to lvl a ftr: you class him on time means he gets in total like 590 crew at lvl 120. if you delay class him at any point the crew size will be bigger. if you wait with classing him from ace ftr to ftr sq ldr your crew will gain +2 more with each lvl. if you then class him at lvl 120 or not at all to sq ldr your crew size will be around 650.

this means you can get more vets on your sailor. due to more vets and experts your real ability will grow and therefor your ftr performs better.

another reason why ppl late class is when they want to keep the ability of 2 stats high.

you get a 12/12 rep/eng. if you class him on time he will lose on the rep or eng ability. if you late class him his ability will grow equal on both but he might not be as good as an on time classed sailor of his class.

overall it means: late classing = more crew = more vets & experts = higher real ability

or: late classing = keep ability of 2 stats higher

the late classing doesnt appeal to each class cuz some classes get a bigger crew growth when classing them.

Hi Friend,

Let me explain the concept of late-classing in detail.

As pointed out by EricIdle:
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Very simply, late classing is the fact of not classing a sailor on time, the objective being a higher growth in a secondary stat in exchange for a lower growth in a primary stat.
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But let me put 1 more advantange of late-classing, which is that the final weight of your late-classed sailor will be lighter than that of on-time-classed sailor, which gives you more room for deck/bulge.

The principal of late-classing is, given the fact that the primary stat of the late-classed sailor grows slower than that of a on-time-classed sailor, you have to make sure, after lvl120, the primary stat of your late-classed sailor can still reach, or, approach the ability cap. Otherwise there is no point in late-classing.

I only play the nation of RN so let's use the RN gunner as an example.

As screenshots shown below, classing RN gunner has 4 steps:
Step1@Level 12:

[NOTE: After this classing, each growth in sailor level gives you 6 more recruit spots.]

Step2@Level 22:

[NOTE: After this classing, each growth in sailor level gives you 7 more recruit spots.]

Step3@Level42

[NOTE: After this classing, each growth in sailor level gives you 8 more recruit spots.]

Step4@Level65 

[NOTE: After this classing, each growth in sailor level gives you 9 more recruit spots.] 

Now, obviously, the primary stats for gunners are:
Accuracy
Reload

The secondary stat which also plays a crucial role in this game is:
Repair

Although AAW and Restore are also secondary stats that are effective on your gunners, they are much less important than the Repair ability. Therefore let's focus on following 3 abilities for the rest of this discussion:
1) Acc
2) Rld
3) Rep

Now the question has become,  how much True Ability (TA) of Rep can your gunners have, without comprimising their Acc/Rld caps?

You may have learned from other sources that the TA cap for Acc and Rld are around 1.6M and 3.0M, respectively. If you class your UK gunners on-time, you will have a total recruit of 1000 rookies or so at level 120. Given the vet cap of 40%, then the highest, potential TA factor from your gunners will be something like 400*4 + 600 = 2,200.

Normally, after boost, panel stats of UK gunners will be something like (depending on base growth) 2,000 in Acc, and 4,500 in Rld, which means their final TAs are: 4.4M and 9.9M, way over their TA caps. So why don't you move some of the redundant TA to the Rep?

This is an Excel worksheet designed to calculate the TAs and the final recuit total of a sailor after reaching level 120.

The base sailor used here is Elite Repair (Rep +13, other +9).

As shown below, if you late-class your gunner at level 99 (i.e., classing it from a normal UK sailor to Reload Huge Gunner at level 99), then at level 120 this sailor will have a total recruit of 734, which gives a vet cap of 290 (it's not that hard to reach this cap under 300% vet conversion rate events).
 As you see, the Acc/Rld TA has reached its cap, respectively, and the Rep TA for a single gunner is 3M.

If you class this sailor to gunner on-time, which is as shown below:
 Then the Rep TA for this sailor will be less than 2M. More over, this sailor will have a total recruit of 989 at level 120, which is about 250 recruits more than the first screenshot, which is about 140 tons heavier than above. And this 140-ton difference only comes from 1 single sailor. If you have 3-4 sailors of this kind, imagine how much more armor you can put on your ship!

So to summarize:
1) Late-class your sailors only when their primary stats can be guaranteed to reach ability caps;

Thanks for your extensive post, jedizorro.

Just one thing to add / correct:

Fighters and bombers are actually the ONLY sailors whose subsequent classings - after "fighter" or "bomber" - lead to LOWER crew growth per level (as MCShorty pointed out correctly). That's why it is recommended never to class them "SQD leader", and only to "Ace fighter/bomber" depending on the vets you are planning to put on.

@ Jedizorro: you made several mistakes in your post

1. As Ericidle posted, Fighter and bomber pilots do have smaller crew growth if you class them to Ace or Squadron leader. Never ever class fighterpilots to Squadron leader, their TA will always be lower than if you'd left them as Ace or just Fighter pilot. Depending on the number of vets you plan on getting for your fighter either leave them as Fighter Pilot or as Ace. At higher vets (above about 200) the fighter pilot has the higher TA. With an eye on unexpected events and maybe a sale in the future I'd leave all fighters at fighter pilot.

2. AAW is an inactive stat, it does nothing.

3. We no longer know where the ACC cap is, but 1.6 M TA might be on the low side. However your reload cap is too high, it's actually at 2.7 M TA.

4 Gunner weight: why aren't you cutting rookies from the gunners? Classed on time gunners with rookies trimmed back to keep the gunners at the reload cap should be lighter than delayed classed gunners with higher repair.

5. Your list of sailors that are worth late classing:

A restorer isn't worthy of being late classed, it shouldn't be classed as a restorer at all.

Planesman shouldn't be late classed tbh: As far as we know there is no cap on air refill, when a sub needs to refill his air he usually wants to spend as little time on the surface as possible. Extra repair will not save him then, not staying as long on the surface to get enough air could save him though. Though late classed planesman will be lighter.

UK/IJN AA gunners should indeed be late classed ( UK much more than IJN). Don't class US to AA ( US pure AA guns suck). KM AA gunners shouldn't be late classed they suffer no reload penalty for classing to AA ( though you can leave them at the first AA classing, later classings do not give you more crew growth).

Sonarman is a sailor you could late class. Sonar ability is capped and it's not so high that late classing won't you allow to reach that cap, saving you quite a bit of repair rate and SD. It comes however at the price that if you trim rookies to keep your sonarman just capped and no more, an on- time-classed  sonarman should be lighter than a late classed sonarman. Weight is quite a critical factor on subs.

Because weight is such a critical factor on subs, I've come to realize that torpedoman aren't such a great choice to class late, especially if you cut rookies to keep the torpedoman at the cap. In order to have a significant repair increase, you'd have to go to such extremes that your torpedo man ends up a lot heavier than a regular torpedoman, and still not improve your repair rate all that much. That weight is imo better spend on your engineers or a repairman.

A Bridge operator is also a sailor that can safely be late classed ( if you plan on vetting even an elite repairer can be late classed as BO).

6 Your list of do not late class:

Completely agree on the repairer.

As noted above completely disagree with Fighter/bomber pilots

Thank you Danita. Please find my updates below.

[QUOTE=danita]

@ Jedizorro: you made several mistakes in your post

1. As Ericidle posted, Fighter and bomber pilots do have smaller crew growth if you class them to Ace or Squadron leader. Never ever class fighterpilots to Squadron leader, their TA will always be lower than if you'd left them as Ace or just Fighter pilot. Depending on the number of vets you plan on getting for your fighter either leave them as Fighter Pilot or as Ace. At higher vets (above about 200) the fighter pilot has the higher TA. With an eye on unexpected events and maybe a sale in the future I'd leave all fighters at fighter pilot.
[Jedizorro] Already corrected in original post. 

2. AAW is an inactive stat, it does nothing.
[Jedizorro] I'm not sure about this. Perhaps we could do tests to confirm this. From what I see, higher AAW means more chance to shoot down medium-level, low-altitude Recon aircrafts.

3. We no longer know where the ACC cap is, but 1.6 M TA might be on the low side. However your reload cap is too high, it's actually at 2.7 M TA.
[Jedizorro] I might not be a bad idea to keep 3.0M TA for reload as no one knows when SDE is going to change. 

4 Gunner weight: why aren't you cutting rookies from the gunners? Classed on time gunners with rookies trimmed back to keep the gunners at the reload cap should be lighter than delayed classed gunners with higher repair.
[Jedizorro] Yes cutting down rookies from gunners is another way to keep gunners light. However, by doing this you will lose almost all Repair ability on gunners. However Repair ability is crucial for many nations, especially KM. Even on RN ships, I prefer to keep Repair ability with my gunners because my QV crew includes 8 late-classed engineers (all of them will add up to 30M Repair TA) and I need the last 5-6 M Repair TA to come from my gunners. With 8 late-classed engineers I have 8 minutes OH time, plus much less weight than the usual 5 engineer + 3 repairer combination or 6+2 combination. Eventually, whether to level late-classed gunners with full crew, or to level on-time-classed gunners with half of crew, will come down to a trade-off between 200 tons of free displacement vs. 6M Repair TA. For me, I choose the 6M Repair TA over 200 tons of free displacement. Moreover, the late-classed gunners with 6M Repair TA are also fantastically suitable for CVs and CA/CL/DD (to level up new crew), and even RN SS.

5. Your list of sailors that are worth late classing:

A restorer isn't worthy of being late classed, it shouldn't be classed as a restorer at all.

Planesman shouldn't be late classed tbh: As far as we know there is no cap on air refill, when a sub needs to refill his air he usually wants to spend as little time on the surface as possible. Extra repair will not save him then, not staying as long on the surface to get enough air could save him though. Though late classed planesman will be lighter.

Because weight is such a critical factor on subs, I've come to realize that torpedoman aren't such a great choice to class late, especially if you cut rookies to keep the torpedoman at the cap. In order to have a significant repair increase, you'd have to go to such extremes that your torpedo man ends up a lot heavier than a regular torpedoman, and still not improve your repair rate all that much. That weight is imo better spend on your engineers or a repairman.
[Jedizorro] I'm going to answer these 2 concerns together. I'm new to SSes so I am very likely to be wrong. Basically, late-classing SS crew is almost the only way for an SS5 (or above) to reach Repair cap, which is 35M Repair TA. You cannot possibly put on 4 Repairers on SS without putting any Engineers, right? However, when your SS reaches Repair cap, I guess it'd be a very different game play than before. You can stay much longer on the surface than before because your enemies are not likely to damage you at a rate that is faster than your own repair...

Now, for the Planesman, I'm using a sailor of Potential=14, Repair=12, Restore=11. I'm going to late class it at level 120, as a way to keep the weight light and as much Repair/Restore TA as possible. Your idea of on-time-classing Planesman is truly valid; I may consider level up another Planesman later.

Now for the Torpedo Man, I'm using Elite Repair. I changed nation at level 12 and am going to class them at level 120, at which point if you give it 40% vet, it will have 2M Torpedo TA and 3M Repair TA, each (i.e. 1 pair of such Torpedo Men will give you 6M Repair TA). Since its Torpedo TA still exceeds the ability cap, you can consider removing rookies from this sailor, but you will still have around 2M Repair TA on each sailor, and its final weight should be close to your on-time-classed Torpedo Man with rookies removed. Again, I would choose Repair TA over a few tons of free displacement.

[/QUOTE]

I know I'm going quite off-topic from the OP, but anyway about crew weight for a SS:

You only pay attention to a SS crew you're building for 2 real reasons HA and fleet competitions, in Gb anything will do and I'm discounting e-peen as valid.

For HA you'll be using SS5 and SS6, I don't know about all the SS5, but my KM SS5 will probably not suffer any problems leaving the harbour even when the crew gets fatter. And I expect other nations will not have major problems either. I don't know the numbers for the SS6 but given their level I don't expect them to develop major crew fitting issues. Likely the SS5 and SS6 only weight issues will be in maintaining a certain speed rather than leaving the harbour.

For Fleet competitions you are at present and likely in the future limited to at best a SS4. Now my KM SS4 doesn't have weight issues ( I run 0 weight BO and torpedomen trimmed down to the torpedo cap on all my subs), but my IJN SS4 does have a weight problem. I have to use a really small weight sailor on the gun slot or leave it empty to leave the harbour in the setup that I want. For lower tier subs I expect it's the same or worse. My KM SS2 can hardly leave the harbour, certainly not in the setup that I prefer and this will only get worse as my KM engineers aren't 120 or even 115 yet.

with high lvl crew you can use a lighter engine if you have weight issues on a SS4 and still be able to speedcap it. 

Not sure if it work for all nations but I run my IJN4 and KM4 submarine with the normal engine and doing the same speeds as with a heavy engine. As bonus it give more OH time too.

Capping sonar isnt possible.

Example of late-classed UK Gunners

http://fm.en.kupaisky.com/Community/Forum/View.aspx?num=18497&searchtype=0&pagecount=0&searchvalue=&sort=5&category=A02&page1=1