You need the diving bell to reach the map at Ambergris Key, located on the second floor of the building. The Heavy Shot upgrade itself is located on the tallest structure on Misteriosa Island. Climb up and look to the left of the water fountain.
On the island of Misteriosa, at 307.195, you can find a blueprint for the elite heavy shot power upgrade; in a buried treasure by the huge structure. You get the treasure map for this buried treasure in Ambergris Key.
It turns out that using heavy missile is almost too easy: You have to fire your cannons (right boom) without aiming. So you have to stop right next to your target, line it up on sight, and then unleash all hell. Your pivoting targets will light up and you can erase a third of a powerful ship’s health in an instant.
Elite Skin Plans are the highest level upgrade for your Jackdaw. To get all the plans, you should visit many Caribbean islands and complete the “Dive for Medicines” story mission. This mission rewards you with a diving bell upgrade that will help you reach the bottom of the ocean.
The treasure map that leads to the Elite Mortar Camp is located on a corpse on the northeast edge of Tortuga Beach. In Mantanzas, go through the village and look for some ruins where you will find the treasure under this recess.
Assassin’s Creed® IV Black Flag Use Heavy Shot to incapacitate the Man O’ War. Sequence 8, Reminder 01: Don’t walk carefully. Do not hold L2 and fire (R2) at the same time, as this will result in a miss. Press L2 to focus but release before firing (R2), it’s as simple as that.
The HMS Prince is the easiest Legendary, so it’s a good idea to try taking it out first to get your feet wet.
The heavy shot is the Jackdaw’s strongest weapon when it comes to dealing damage. It cannot be aimed like the normal round-shot and cannot shoot very far due to its weight. It is also a finite resource and is stored on the ship, unlike Chain Shot and Round Shot, which are unlimited.
The Jackdaw is a military clipper fully equipped for naval combat. Jackdaw can be upgraded with more cannons, stronger hulls, new skills and new weapons; You saw many of these in AC3. In addition to upgrades, the Jackdaw can be repaired and will have an expandable crew.
The Heavy Shot upgrade itself is located on the tallest structure on Misteriosa Island. Climb up and look to the left of the water fountain.
PSA: A fully upgraded jackdaw is level 45, so consider that before you go into battle.