Brigantine gets two sets of damage bonuses, a 20% inherent bonus to all flooding weapons, and another 20% when the target is flooded. The aim of this build is to maintain flooding as long as possible to get that second bonus using Bilgefire Barrels

Basilisk III's work well for that, since they're all deck weapons, and more hits equals more chances to reset flooding timer. Demi Cannons would work too, but they don't have as many suitable options for adding flooding. Rupturing and Overflow are the mods we want on them to trigger flooding as soon as possible. Amplified Flooding is the ideal blue mod, but if you have preferences for other ones, feel free to use them too.

At the rear, Lange Kartouwe is a good option, since we can't have all deck weapons there. The perk of this weapon makes it one of the best options when you only have 2 gun ports available. We want Rupturing on it as well to increase its damage on Brigantine, but other mods won't matter too much.

For Aux, Little Grace III is a must have. Putting Empower on it allows you to give yourself another 15% damage increase. You should also grab Fix, since keeping your health topped up with Nocturne Heart is another 15% damage increase. For blue mods, you can use Restorative to deal with severe damage or Sailor's Respite for even stronger healing.

The rest of the furniture will be Ramrod Workshop as it's a must have for all builds, Machinist Table (Repair) I as it improves Little Grace 3 quite a bit, and whatever other damage increasing furniture available, in this case Culverin Works I, Port Powder Kegs I, Starboard Powder Kegs I. You can exchange these for any other more utility focused furniture too if you so wish.