Translated by Babykim.
Important official info on the upcoming ranked battles (season 4):
The developer Vallter_ says:
We know that players would want to prepare their ships and captains for upcoming ranked battle seasons, and therefore need to know which tiers will be eligible. The next ranked battles – season 4 will be held at tiers V, VI and VII. Those who are confident that they will reach rank 1 may prepare their tier X ships.
EDIT: You will be able to test the ranked battles during the general test for the update 0.5.6, which will take place during the coming two weeks.