Some additional feedback after playing for a while. The update you made made it much easier to understand the game and with some battle practice I managed to get much further. My experience can be divided into 3 parts:
Beginning - this is not very fun. The ship is too slow and hard to turn and battles are very long and hard to win. You get game over a lot until you've learned the trick. Delivery quests are a pain because they take ages.
Middle - after upgrading steering, speed, and cannon cooldown a bit the battles become quite fun. Not too easy, not too hard and it's not frustrating to maneuver the ship. Delivery quests are interesting because they make you explore a bit.
End - you quite quickly max out the upgrades and battles become too easy. Finding enemy ships becomes the new problem and this is not fun as it's just trudging on an on over an endless sea. You've seen the same island many times over and delivery quests are not interesting anymore.
If you find a way to make starting out more engaging, and add more variety and balanced difficulty for the endgame, this could be great!