When you are at sea, the hardest thing I see for people to do is maintaining distance from the other ships.
here's the thing you should do.
1. when you near a ship, give the "open fire" battle order, then fire the broadsides, and if you are on a sloop or war sloop, get off the whell, take a cannon, and fire an explosive, if Open fire is still in effect, it is almost a garunteed sink depending on how high you have explosives.
2. when sustaining heavy fire, execute the "take cover" command to reduce damage to a mere quarter of what it would be.
3. know the ship you need, sloop for speed, galleon for cargo and broadside cannons.
4. when the ship's hull changes color to yellow, finish off the ship you are assaulting and then flee to a safe spot for repair, a full repair.
5. "ah repair is for the weak" I have only one thing to say, don't get cocky and good luck.