Every mate starts at rank 1 and can be trained up to rank 5. Each promotion increases his stats by perhaps 10% or so. Each promotion also allows having an additional mate skill active at a time, up to 4. Finally, each promotion makes it so that more skills are available to be used, as follows:

Rank 2 (silver, two chevrons): unlocks two character effect mate skills if the mate is at least level 30
Rank 3 (gold, three chevrons): unlocks naval combat skill if the mate is at least level 50
Rank 4 (green, four chevrons): unlocks final two job effect skills if the mate is at least level 70
Rank 5 (red with yellow star): unlocks final two character effect skills if the mate is at least level 90.

A relative handful of mates have a natural skill that the mate learns at level 99 replace one of the character effect skills that would normally be unlocked at either level 30 or level 90.

You can promote mates from the promote tab of the mate screen. Promotion costs contracts, astrolabes, appointments, and ducats. The cost in ducats is generally pretty trivial, but the others are the real cost.

For contracts, you need contracts for the particular mate, though you can substitute generic contracts of the same grade as the mate. Generic contracts are fairly rare, though, so you can't do this very often.

You always need the same number and grade of astrolabes as appointments. Appointments are generally more common than astrolabes. However, there are separate appointments for adventuring, trade, and combat mates. Requiring appointments makes it more difficult to use your astrolabes to mostly focus on promoting one particular type of mate.

The cost in materials of promotions depends on the grade of the mate, as follows:

C-grade mates:

B-grade mates:

A-grade mates:

S-grade mates:

After a mate has reached rank 5, you can train him up to higher grades. That is, you can turn a natural C-grade mate into B-grade, then A, then S, and finally even SS. This takes additional contracts, astrolabes, and appointments. It also takes some training manuals. As before, appointments are more common than astrolabes. Training manuals are also plenty common enough to not really be much of a restriction. Each step of training costs 100 blue gems, but no ducats.

When you train a mate, you increase his stats to be in line with that of the next higher grade, which commonly means roughly doubling his stats. The mate also gains some training points. Each training point increase one stat by 10. There are caps on how many training points can be allocated to a given stat for a given mate.

Training a mate does not change his mate skills or naval combat skills. Higher natural grade mates tend to have stronger skills, and that does not change. Training does not increase a mate's language skills, either. Again, mates with a higher natural grade tend to have higher language skills, though there are exceptions.

The cap on training points in a given stat per mate by mate grade are as follows:


The number of training points that a mate gains by increasing his grade are as follows:


Mates with a higher natural grade lose out on the training points that would have been obtained by training the mate from a lower grade up to his natural grade. Thus, for example, a natural C-grade mate trained up to A-grade has 75+90 = 165 training points available, while a natural B-grade mate trained up to A-grade only has 90.

When training a mate up to a higher grade, you need two grades each of astrolabes and appointments. You need the same number of each of the four types of items, however. The number of each of these items matches the number of mate contracts that you will need, so it is the same number for each of five items.

If you wish to substitute generic contracts for contracts specific to a particular mate, the generic contract grade must be that of the mate's current grade, not his natural grade. For example, if you wish to train a natural C-grade mate from A-grade to S-grade, you can use the mate's own C-grade contracts, but to substitute generic contracts, you would need A-grade.

The costs of training mates to higher grades are:

Natural C-grade mates:

Natural B-grade mates:

Natural A-grade mates:

I have never trained a natural A-grade mate up to S-grade, so I can't see the cost to train an S-grade mate up to SS. Considering the patterns in other tables, it's probable that it takes 85 of each of the types of A and S grade materials relevant.

I do not have any natural S-grade mate promoted to rank 5, so I cannot see the cost of training him up to SS grade. That's so far into whale territory that I don't particularly care about the cost, though.

The main source for most contracts is the gachas. Unless you're a whale, this generally means the normal mate gacha. Over the course of several months of playing the game, you can eventually get enough contracts from that gacha to train up some natural C-grade mates all the way to SS.

The other major source of contracts is combat dispatch. Named combat dispatches commonly give large numbers of contracts for the named mate. This allows you to get the 350 contracts that it takes to train a natural C-grade mate up to SS-grade very quickly. Some players have thousands of contracts for a given mate and sell the spares cheaply on the auction house, which makes it possible for newer players to buy bulk contracts for those particular mates cheaply.

Mates with contracts that are readily available like this seem to all be natural C-grade mates. The mates in question are:

Trade: Catherine Cornaro, Nicolas Flamel, Asarpay, Jan Joosten van Lodensteijn, Matsura Takanobu
Combat: Victor Russell, Richard Huxley, William Clive, Ambrosius Ehinger, Hisakajima Yasuke

Based on dispatch names, Georg von Speyer, Robert Wilde, and Jakob Roggeveen may also have contracts available from dispatch, but I haven't seen those contracts appear on the auction house in bulk. The Wilde and Roggeveen dispatches require such high level fleets that it is likely that no one does them yet.

Astrolabes and appointments generally come from the same sources. There are two major sources of them and several minor sources. One major source is events, though the details vary considerably by event.

The other major source is land training, which can be done up to 3 times per day, or 5 if you're a whale and buy the Grace of Raphael effect. You get no reward from unsuccessful land training, and a somewhat random but partially predictable reward for successful training. Land training is like land exploration, except that the fourth and sixth slots are always gather (just like land exploration), while the rest of the slots are always explore and never combat.

You generally get higher trade astrolabes and appointments for higher difficulty land training. A rough table looks like this:


155a is for 155 difficulty in zones that required company level 55 at launch, which are around Australia. 155b is for 155 difficulty in zones that required company level 60 at launch, which are predominantly in northeast Asia.

The types of appointments vary by location, but the boundaries don't necessarily coincide with land exploration zone boundaries. For example, if land training in a given position gives trade appointments, then all appointments from training at that particular location will always be trade and never adventuring or combat. Some other location will always give combat and not trade or adventuring. The exception is that for difficulty 155b and higher, you get some of each type of appointment rather than only one. Until then, this allows you to select the particular type of appointment that you wish to farm.