Assassin's Creed 4: Black Flag Walkthrough Part 13 – Sequence 3: “Raise the Black Flag”
Optional Objectives:
Plunder a Hunter Ship
Plunder 30 Sugar
Head for Salt Key. This port is a good distance away but not too hard to get to once you are there. Just sail into the marked area in front of the dock and hit the prompted button. The crew will haul in the ship and bring it along side the dock. If you do not want to wait that long, then just jump into the water and swim over to the dock. From there just head on in.
Just down the pier you will find the Harbor Master. Talk with him and this will open up all the options to upgrade the Jackdaw. Some are still locked as you need to find the bluepriunts to use them. Once you are ready though get ready for more energetic enemies. The only other Jackdaw upgrade right now are the Broadside Cannons. This is recommended when you have the Metal for it as they vastly add to the raw firepower the Jackdaw has. The more power you have, the quicker you can take down a ship and reap the prizes found within.
Now it is time to get introduced to the Maritime Wanted System. Just was you have notoriety on land, you can be sought after on the seas as well. Now there are consequences to your acts of piracy. If you stocked up on Sugar before starting this section, you have little to worry about right now for that optional objective. Now you just need to head on out to sea and begin looting once again.
Once you are out on the sea, one of Edward's men will spot a military brig. Time for real maritime combat. These brigs are a lot tougher and have much better armaments then the small ships you were hunting before. They will fight back with much more ferocity so be ready for a much longer battle before you can claim the ship as a prize.
Once the ship is in the red, move in and board it. You have 10 crew to kill now instead of 5. Remember Edward can use the swivel guns to take out enemy crew. Start with that then move over to the ship for hand to hand combat. Remember to use both swords and pistols will serve you well. Add in a solid kill steak while at it and you will have no problem taking down the crew and claiming as your plunder.
With the first ship down, you will have a level of Notoriety. This will mean there is a Hunter Ship out on the seas looking for the Jackdaw. It is marked on your map with a Red Marker. If you want to complete the optional objectives, then you need to hunt down the Hunter and take them on in combat.
The Hunter is no easy prey, being a bit harder than the brig (or 2) you just took. Once you are ready to board her, you need to kill off 10 crew before the ship can be taken. They are usually a bit tougher than what you were encountering before. Be ready for that. After that it is just the same as you were doing earlier, you are prompted to return to Salt Key.
Once back at Salt Key, you will be meeting your first Government Official. Head over to the marked man and pay him off. This will get rid of the wanted level you acquired while as sea. After that you need to head on back tot he Jackdaw.
Once on board go into the Captain's Quarters. There you will find a model of the Jackdaw. Head over to it and interact with it. This will bring up the upgrade menu for the ship. Purchase the upgrade for the cannons and you are ready fro the next part. Head back out to the deck and ship will be upgraded.