The Jackdaw starts out weak enough that it struggles against anything bigger than a light schooner, so every serious naval fight in Assassin’s Creed Black Flag Resynced runs through the Harbourmaster’s upgrade menu. Maxing the ship takes four common resources plus a set of rare blueprints called Ultimate Ship Plans, and both are scattered across the Caribbean in predictable places.
Quick answer: Fully upgrading the Jackdaw and the Great Inagua Harbourmaster costs 309,800 Reales, 4,755 Metal, 2,750 Wood, and 550 Cloth, and it also requires all 12 Ultimate Ship Plans. Gather resources by boarding and sinking ships, capturing forts, and running Kenway’s Fleet; collect the plans from six underwater shipwrecks and six buried treasures.
The four ship upgrade materials and how to farm them
The Jackdaw upgrade system opens during the Prizes and Plunder mission, when the game first sends you to a Harbourmaster. After that, you can buy upgrades from any Harbourmaster as long as you have the resources. Four materials drive everything, and each has a reliable source.
| Material | Best way to farm it |
|---|---|
| Wood | Board and sink enemy ships. |
| Metal | Board and sink larger vessels such as Frigates and Man o’ Wars. Capturing forts hands over a large one-time amount. |
| Cloth | Loot ships, and raid the plantations dotted around the Caribbean. |
| Reales | Board and loot ships, sell trade goods like Rum and Sugar to Harbourmasters and General Stores, raid warehouses, and collect passive income from Kenway’s Fleet. |
Kenway’s Fleet unlocks in Sequence 4 and is the least tedious money source. Send out five Schooners to generate Reales and five Brigs to generate materials, then collect the rewards as missions complete while you handle other things. This keeps the 309,800 Reales total from feeling like a grind.
Ultimate Ship Plans: what they are and the Diving Bell requirement
Once you max the Harbourmaster at Great Inagua, the final tier of nearly every ship part demands an Ultimate Ship Plan. There are 12 of them. Six sit inside underwater shipwrecks, and those six also grant the strongest upgrades. The other six come from digging up buried treasure, which means finding the right Treasure Map first, then locating the dig site it points to.
The six underwater plans require the Diving Bell, which unlocks after you finish Sequence 06 – Mission 01: Diving for Medicines. Inside a wreck, an Ultimate Plan always sits in a larger Secret chest rather than a standard chest, so fully sweep each dive zone. Nothing here is missable, and you can collect everything after the story ends.
All 6 diving shipwreck plan locations
Take the Diving Bell to each spot below. Coordinates mark the dive zone, and the chest is usually tucked into a broken hull or at the far end of a cave passage.
| Ultimate Plan | Where to find it |
|---|---|
| Hull Armor | San Ignacio Wreck (348, 744), Dry Tortuga Sea northeast of Havana. Head to the very back of the dive and open the large chest in a half-sunken ship. |
| Mortars | Antocha Wreck (600, 636), northwest of Great Inagua. Watch for the shark; the chest is on the right inside the wreckage. |
| Ram | La Concepción Wreck (150, 272), Chinchorro Sea, southeast of Fort Chinchorro. Swim directly north from the bell to the nearby broken ship. |
| Swivel Guns | Devil’s Eye Caverns (453, 331), Cruz Sea. Take the long path to the right and up north, climb out onto dry land, and grab the chest. The left path is exit only. |
| Broadside Cannons Number | The Blue Hole (440, 145), Charlotte Sea, west of Kingston. The chest sits in a corner of the sea floor with no obvious wreck around it. |
| Round Shot Strength | Kabah Ruins (738, 120), Navassa Sea, east of Kingston. Follow the long cavern to the north end of the dive zone; another shark patrols here. |
All 6 Treasure Map plan locations
For these, collect the Treasure Map at the first location, then travel to the dig site to uncover the chest. Edward will comment when you are standing near buried treasure, which helps confirm the exact spot.
| Ultimate Plan | Map location → dig site |
|---|---|
| Heavy Shot Strength | Map at Ambergris Key (28, 160) → dig at Misteriosa (271, 178), near the fountain behind the Mayan temple at the top viewpoint. |
| Fire Barrel Strength | Map at Santanillas (191, 218) → dig at San Juan (455, 462), just inside the smuggler’s cove near the first guard. |
| Heavy Shot Storage | Map at Cayman Sound (298, 311) → dig at Petite Caverne (863, 235), behind the waterfall near the Hutia hunting spot. |
| Mortar Storage | Map at Tortuga (851, 352) → dig at Matanzas (312, 617), left of the Mayan Stelae behind the waterfall. |
| Fire Barrel Storage | Map at Petite Caverne (862, 237) → dig at Tulum (40, 372), at the southernmost point among the beach shipwrecks. |
| Harpoon Strength | Map at Mariguana Island (847, 514) → dig at Andreas Island (544, 693), on the small patch of land at the southern tip. |
A quick sequencing tip. Grab the Treasure Map from Santanillas before you visit Petite Caverne, since Petite Caverne itself holds the map that points to Tulum. Planning your route this way avoids doubling back across the map.
How to confirm the Jackdaw is fully upgraded
Bring each Ultimate Plan to the Harbourmaster’s “Upgrade Ship” menu, where the final tier of the matching part becomes buyable once you also have the Reales and materials. When the last upgrade is purchased, the Ship This trophy and achievement unlocks, which is the clearest sign every part is maxed. If a final upgrade still shows as locked, you are either missing that part’s Ultimate Plan or you have not yet fully upgraded the Great Inagua Harbourmaster, which gates the top tier.
