Maxing out the Jackdaw is one of the most satisfying things you can do in Assassin's Creed Black Flag Resynced, and the 12 Ultimate Ship Plans sitting at the top of the upgrade tree are the final piece of that puzzle. The problem is that several of their locations have shifted from the original 2013 game, meaning old guides will send you on a wild goose chase.
Here's the lowdown on all 12 plans, what you need to grab them, and where things are different from the original Black Flag.
What the diving bell changes about this hunt
A large chunk of the Ultimate Plans are locked behind underwater locations, which means you need the diving bell before you can even attempt them. Seven of the 12 require it. The other five are found on land or through treasure map chains, though a couple of those map hunts involve swimming through submerged tunnels to reach the dig site.
The key here is to not rush this until you have the diving bell unlocked. Trying to brute-force the underwater spots without it wastes time.
The seven underwater plans
These are the most straightforward of the bunch, each tied to a specific wreck or dive site on the map.
- Hull Armor Ultimate Plan at the San Ignacio Wreck (352, 744). Swim to the very back of the area and open the large treasure chest.
- Round Shot Ultimate Plan at Kabah Ruins (738, 120). Swim all the way to the back of the area. Watch out for the shark.
- Mortars Ultimate Plan at the Antocha Wreck (600, 636). Head right inside the ship wreckage once underwater.
- Swivel Ultimate Plan at Devil's Eye Caverns (453, 331). Take the right-hand path north through the cavern. The left path is exit only, which trips a lot of players up.
- Ram Ultimate Plan at the La Concepcion Wreck (150, 272). Head directly north from the diving bell drop point.
- Broadside Cannons Number Ultimate Plan at the Blue Hole (437, 145). Swim all the way to the back of the site.
- Heavy Shot Strength Ultimate Plan at Ambergris Key (30, 159), but this one works differently than the others.
The Ambergris Key plan is worth calling out separately. Unlike the original Black Flag, you do not need the diving bell here. Instead, look for the broken shade sail near an opening and swim through a long underwater tunnel. There is a mid-tunnel cove to surface for air if needed. Enemies wait at the far end, but the plan is yours once you clear them.
The five treasure map plans
These require finding a map first, then travelling to a separate location to dig up the actual plan. Two of them have changed location from the original game.
- Fire Barrel Strength Ultimate Plan: Grab the treasure map from a skeleton at Santanillas (191, 218), northeast corner. The chest is at San Juan (454, 462). No diving bell needed in Resynced, but the entrance is tricky. Park the Jackdaw offshore, swim to a small boat on the surface, then dive straight down to find a blue-lit tunnel opening on the seafloor.
- Heavy Shot Storage Ultimate Plan: Treasure map is at Cayman Sound (298, 311), upper left north side near some wreckage. The chest is at Petite Caverne (864, 237), behind a waterfall next to a campfire in the middle of the cavern.
- Fire Barrel Storage Ultimate Plan: This one is completely different from the original Black Flag. Pick up the map from a skeleton at Petite Caverne (864, 237), then travel to Tulum (40, 372) to find the chest in front of some broken debris. Much easier than the original location.
- Mortar Storage Ultimate Plan: Map is buried near a skeleton at Tortuga (852, 352), northeast side. The chest is at Matanzas (304, 622), behind a waterfall at the back of the island.
- Harpoon Strength Ultimate Plan: Map is inside Mariguana Island (847, 514) through a crawl gap, next to a skeleton at the end. The treasure is at Andreas Island (545, 693), at the southernmost point of the island behind two trees.
What most players miss about the Resynced versions
Three plans in particular catch returning Black Flag players off guard. The Heavy Shot Strength plan at Ambergris Key drops the diving bell requirement. The Fire Barrel Strength plan at San Juan also drops it, though the hidden tunnel entrance is genuinely hard to spot without knowing what you are looking for. The Fire Barrel Storage plan moves entirely, from a complicated original location to a straightforward chest at Tulum.
If you played the original game and memorized those spots, unlearn them for these three specifically.
For more on gearing up in Resynced, the AC Black Flag Resynced guide collection covers everything from unlocking the Shipwright to tracking down collectibles across the Caribbean.
