: Check out the Pixel Piracy Walkthrough
EDIT: User Shh I am Batman has pointed out to me that the ships all spawn in at the beginning of the game; there is no order and it was just coincidence that I met the cannon-bearing ship last on two separate runs.
This solution was inspired by the other two.
There are 4 legendary ships. All of them have a very strong crew, but only one of them has cannons. Abuse the save system in the game to make sure you fight the cannon-bearing ship last.
Get together a crew of 10 additional members and teach them all Cannon Mastery, then add 10 cannons to your ship and fill the remaining area with a bunch of cannonballs, then just attack from afar for the first 3 legendary ships.
Your crew will level up to about 90 after these three battles. Again, abuse the save system to make sure you do not lose any members along the way. Use the skill points earned to make sure each member has 50 vitality, then put the rest into dexterity. Each crew member should end up with over 100 dexterity.
For the final ship, take the cannons back off so your crew is not tempted to use them, and equip your entire team with flintlock pistols. Board the ship and wait for your party to take out the entire enemy crew in about 10 minutes.