You get XP from two sources.
- The longer at sea you are the more XP you get, you can track this by opening the fleet menu at sea.
- you gain XP from sinking ships, sinking ships or fleets that have a higher battle rating than yours rewards more XP. This can be seen by opening the list of combatants in battle.
This is also a hindrance as if your battle rating is higher than your target then you get less.

XP is calcuted in a lot of manners, but it's MOSTLY damage dealt !

If you want to make EASY and very fast XP ! You need to go on a Search and Destroy mission that asks you to kill 2 L'ocean.

That's what i did in my last time playing this game, i went in a clan, the guy would take the mission with me, we get into the battle. I take a small sloop/snow. He destroys the masts of every ennemy ship, then i just have to go behind, and shoot the back for 50 minutes.

If i remember, got like 1300+ XP from those ? It was extremely effective, and he just had to leave the battle right after destroying the masts, he had nothing else to do x)

It can be done alone also. Go VS 2 L'ocean (Later, once you have something like a constit), break the masts of the first at the start of battle, kill the second, then finish the first. EZ XP.

Second manner would be AFK on open seas. Which i also did for some time. Missions, or trade missions were also giving some XP, but not very much and it's boring :(

Pirate exam also brings you a lot of XP (I dodn't remember how much, but it's quite good).

You have to kill 2 sloops. The strat is to gradually go in front of the ennemy ships and then switch from side-to-side, pelting them with balls as they try to close the distance. But since you're a player, and they're slightly slower than you, you're safe.

That's how you kill a lot of ships without too much issues. Used this kind of strategy to also kill players. (Fun part is : I only understood they were a player once i got the battle results, i only noticed this AI was acting weird xD) #Ye I'm unaware as f.