To have a total of 30-40 on a sailor? Not many, probably average about 100 experts. You could get lucky and do it with 50, you could be unlucky and need more like 150.

If you mean to boost your sailors by another 30-40 ontop of the ~100 they have now, you're looking at much closer to 400-600 experts I reckon.

I don't know what variables affect the success rate, my experience includes the premium sub bonus. If maximum sailors is a variable then that might account for something, but personally I think it simply gets harder with every success. It's pretty hard to pin down the exact rate of success.

However, to answer wether you need more, that IS a pretty generalised question. You should read Norms repost of adalberts guide to ability here in the tips section. It isnt entirely up to date any more, but it does outline the basics of calcuating a sailors true ability with each stat.

Ability caps I know of;

Reload, which caps at 2.7m reload. You can consider 2.4m the cap for AA gunners.

Repair, which caps at 35m (shared across your entire crew, so every sailor contributes to this total cap).

Accuracy, which is 4706 x the sailors level +1,100,000 (it was only 1m, but the cap was increased and no one knows by how much, so I have assumed a roughly ~10% increase is enough. Most sailors have easily capped accuracy if they have capped reload, the exceptions are UK and USN sailors of certain class combinations, you'll have to investigate your gunners ability more indepth if this is the case).

Wether you have enough vets or not will depend on what ability that sailor needs. 100 is a nice, basic amount for most sailors. Gunners with full experts will easily cap their abilities eventually, but doing so earlier obviously requires the presence of vets. 100 will get you capped between 90-100 most nations, 200 gets you capped in the late 70s. Repair is one you have to figure out first, obviously most sailors dont contribute very much repair at all. But basically, you need to look at the individual sailors and their abities to decide if they have enough vets for your needs.

Thank You very much ! great answers!

I was refering to 30-40 above and beyond the 100+ already on each.

Since most are approx. lvl 90 - 100 i woul imagine they are close to their caps already?

You can convert experts fairly easily when your level is low and your vet count is below 100.

But if you have 120 or more vets and your level is 100+, your conversion rate is essentially zero.

As an experiment, I took my Sub's BO at L110 and burned 700 experts.  Not one vet was created.  

I run most my senior level sailors at 100-140 vets, but run very high levels of experts and occasionally burn a few when I feel lucky.  

There might be some optimum level when to burn through experts to get vets, I'm just not sure what level?

Yeah, I think the sailor's level is quite an important factor.

I got my 8 KM supports that are all lvl 82 from 159 to 179 vets, obtaining 160 vets in total with 1260 experts burned. That gives me a conversion rate of nearly 13%.

Of course, that was during the 300% vet conversion rate weekend, and I was on premium.

Just as a note of caution: don't try this and blame me for it when you are disappointed... :)

Remember this. 1 vet is worth 4 experts. So you if you burn 400 experts and get less than 100 vets, your ability total would be reduced.

If you're going to do it, make sure you have some experts to refill those you have lost so you actually benefit from increased ability.

Adelberts guide said that the probability of rolling a vet was 10% for each roll.

Stealth spent 800 experts for 80 vets which comes out at the Adelbert 10% number.

So, to get 100 vets assuming the 10% number, you will have to burn 1000 experts.

The comment that 4 vets equals 1 expert is correct. 

As to accuracy cap....gunners hit it about lvl 70 and no additional amount of vets or experts will increase accuracy.

If you want to calculate true ability for your sailors....go here: 


http://www.tarrif.net/cgi/production/nf_ability_calculator.php