AC Black Flag Resynced: All Final Ship Upgrade Locations (Ultimate Plans)

• There are 12 Ultimate Plans needed to unlock the Jackdaw’s final ship upgrades in AC Black Flag Resynced.
• 6 plans are found in underwater shipwrecks — you need the Diving Bell first.
• 6 plans are buried in treasure chests linked to specific Treasure Maps.
• The Diving Bell unlocks after completing Sequence 6, Mission 1: Diving for Medicines.
• You also need to upgrade the Harbourmaster at Great Inagua to Tier 3 before any final upgrade can be purchased.
• Full cost to max out the Jackdaw: 309,800 Reales, 4,755 Metal, 2,750 Wood, and 550 Cloth.
• Nothing is missable — all 12 plans are available even after the main story ends.

AC Black Flag Resynced Ultimate Plans are the key to fully upgrading the Jackdaw. These blueprints replace what the 2013 original called Elite Ship Upgrades. You cannot buy them from any store. Each one unlocks the top-tier version of a specific ship stat — things like Hull Armor, Broadside Cannons, and Fire Barrel Storage. Once you have a plan, head to any Harbourmaster and the final upgrade for that part becomes available to purchase with Reales and materials. Get the game on PlayStation, Xbox, Steam, or Epic Games.

What Are Ultimate Plans in AC Black Flag Resynced?

Ultimate Plans are rare blueprints that unlock the final upgrade tier for each part of the Jackdaw. You need to find the correct plan before the matching upgrade becomes available at the Harbourmaster. They cannot be bought — only found in the open world.

Before you start collecting them, make sure you have upgraded the Harbourmaster at Great Inagua to Tier 3. This costs 500 Reales to build, 2,500 Reales for Tier 2, and 5,000 Reales for Tier 3. Without hitting Tier 3, the final upgrade slot will still appear locked even if you have the plan in hand.

If you want to save up resources faster, check our Metal and Wood farming guide and our Kenway’s Fleet guide to earn money passively from Sequence 4 onwards.

How to Get the Diving Bell

Six of the twelve plans sit inside underwater shipwrecks. You cannot reach them without the Diving Bell. Complete Sequence 6, Mission 1: Diving for Medicines to unlock it. Once attached to the Jackdaw, all dive sites become accessible and show on the map. The six shipwreck plans also tend to cover the strongest upgrades in the set, so these are worth prioritising.

All 12 Ultimate Plan Locations in AC Black Flag Resynced

Below is every plan, split by how you get it. Coordinates are listed in the format used on the in-game map.

Ultimate Plans from Underwater Shipwrecks

These six are locked until you have the Diving Bell from Sequence 6. Each one sits in an underwater chest at a named dive site.

1. Hull Armor Ultimate Plan

Location: San Ignacio Shipwreck — coordinates (348, 744). Dive down and look for the chest inside the wreck structure. This upgrade is worth getting first since better hull armor dramatically improves your survival in any naval fight. See our full ship upgrade and customisation guide for context on the full upgrade path.

2. Mortars Ultimate Plan

Location: Antocha Shipwreck — coordinates (600, 636). Swim into the wreck and find the chest in the main hull section. Upgraded mortars are extremely useful for the legendary ships mortar trick, so grab this one early if you plan to take on those fights.

3. Ram Ultimate Plan

Location: La Concepción Shipwreck — coordinates (150, 271). The chest is inside the wreck. A strong ram makes boarding runs much more effective, especially against brigs and frigates.

4. Swivel Guns Ultimate Plan

Location: Devil’s Eye Caverns Shipwreck — coordinates (456, 332). Navigate into the cavern dive site and collect the chest. Swivel guns are excellent for targeting crew when boarding, making fights faster and cheaper on repairs.

5. Broadside Cannons Number Ultimate Plan

Location: The Blue Hole Shipwreck — coordinates (440, 145). This is one of the most important upgrades in the game. More broadside cannons means more damage per volley, which shortens every naval fight significantly.

6. Round Shot Strength Ultimate Plan

Location: Kabah Ruins Shipwreck — coordinates (735, 119), east of Kingston in the Navassa Sea. After diving with the Diving Bell, swim through a small gap to the north and follow the cavern all the way to the far end. The chest is at the back. Kabah Ruins also has one of the highest chest counts of any dive site, so clear the whole area while you are here.

Ultimate Plans from Treasure Maps

The remaining six plans come from buried treasure chests. You first pick up a Treasure Map at a specific location. Then you take it to a different location to dig up the chest. Both the map pickup point and the dig site are listed for each one below. You can also browse our full treasure map locations guide for more detail.

7. Heavy Shot Strength Ultimate Plan

Map pickup: Ambergris Key (28, 160) — swim into the cave via the underwater tunnel, enter the large room with a locked chest and enemies, then climb the pillars in the middle to find the map on the upper floor.

Dig site: Misteriosa (271, 178) — fast travel to the viewpoint but turn around instead of jumping off. There is a water fountain behind the Mayan temple at the top level. The buried treasure is to the left of that fountain in the grass, near tall white flowers. For more on this island, see our Misteriosa Mayan Stone guide.

8. Fire Barrel Strength Ultimate Plan

Map pickup: Santanillas (191, 218) — climb the small hill using the tree branches around it to find the map at the top.

Dig site: San Juan (455, 462) — swim into the cave through the underwater tunnel. As soon as you exit the water there is a cave section with a single enemy. The chest is on the right, just before the wooden scaffold.

9. Heavy Shot Storage Ultimate Plan

Map pickup: Cayman Sound (298, 311) — the map is on a skeleton lying at the beach.

Dig site: Petite Caverne (863, 235) — go to the Hutia hunting spot at the southern edge of the cave interior. The chest is behind the rocks near a small waterfall.

10. Mortar Storage Ultimate Plan

Map pickup: Tortuga (851, 352) — head to the eastern shoreline and pick up the map from a skeleton on the beach.

Dig site: Matanzas (312, 617) — go to the south-east corner of Matanzas. The buried chest is to the left of the Mayan Stelae behind the waterfall.

11. Harpoon Strength Ultimate Plan

Map pickup: Mariguana Island (847, 514) — approach the map icon from the north. There is a small cave with a narrow tunnel hidden behind green leaves about 8 metres from the marker. Crouch and go through the tunnel to find the map inside.

Dig site: Andreas Island (544, 693) — the chest is on a small island in the southern section of Andreas Island.

12. Fire Barrel Storage Ultimate Plan

Map pickup: Petite Caverne (862, 237) — find the map on a skeleton inside the cave.

Dig site: Tulum (40, 372) — go to the southernmost tip of the island, to the beach behind a shipwreck. Dig there to find the chest.

What to Do After Getting All 12 Ultimate Plans

Once you have collected all 12 plans, take them to the Harbourmaster at Great Inagua (make sure it is fully upgraded to Tier 3). Each final upgrade is then available to purchase using Reales, Metal, Wood, and Cloth. Buying every upgrade unlocks the Ship This trophy and achievement.

With a fully upgraded Jackdaw, you are ready to take on everything the Caribbean can throw at you. That includes all six legendary ships and the toughest new naval encounter in the game. If you still have content to finish, check out our what to do after the main story guide for a full list of activities. You may also still need to collect all Mayan Stelae, complete the Templar Hunts, or finish all Assassin Contracts.

For base-building, make sure you have used the Great Inagua upgrades guide to get the most out of your home base, and check the crafting guide to make sure Edward’s gear is also maxed out alongside the Jackdaw.

For free bonus items, see our free Crimson Storm Sails and Animus Keys code guide and the free legendary gear claim guide.

And if you want all the active reward codes in one place, our AC Black Flag Resynced all codes page is kept up to date.

All 12 Ultimate Plans Quick Reference Table

Tips for Collecting All Ultimate Plans Faster

• Do the shipwreck plans first. They give the strongest upgrades and you can clear each dive site fully in one visit.
• Buy Hull Armor and Broadside Cannons early. These have the most impact on naval combat. Hull Armor makes you harder to sink. More cannons means more damage per broadside.
• Use Kenway’s Fleet to earn resources passively. Send five Schooners for Reales and five Brigs for Metal and Wood. This runs in the background even when you are exploring on foot.
• Do not rush buying all 12 upgrades at once. The full cost is around 309,800 Reales plus thousands of Metal and Wood. Prioritise the upgrades you need for the fights you are facing.
• Upgrade the Harbourmaster first. Without Tier 3, you cannot buy any final-tier upgrade even with the plan in hand. Spend the 5,000 Reales on Tier 3 before anything else.

Also check our beginner tips guide and the full list of all main and side missions if you want a broader overview of everything in the game.

Frequently Asked Questions