There’s a difference between plunder and the gold pieces in a pirate’s pocket. While gold doubloons and fabulous jewellery can be plunder, pirates are rarely lucky enough to encounter a ship with a hold full of such treasures. Typically, there are trade goods, foodstuffs, spices, and valuables of a more mundane sort. Such takes can fetch significant prices, but for their full worth to be realized, they must be sold at port-side markets. No pirate crew wants to be paid in barrels of salt and pouches of spice after all!
1 point of plunder is roughly equivalent to 1000gp worth of trade goods and typically takes up 10 tons of cargo capacity. Exact values may vary depending on the composition of the plunder (DM’s discretion) but if not specified, default to this.
Plunder can be used in one of two ways: it can be sold, or it can flaunted.
Selling plunder requires one of the pirate player characters (or a cohort if using the Leadership feat) to go ashore for 1 full day, working the markets and seeking out the trader(s) offering the best prices for their goods. At the end of this day, one point of plunder may be exchanged for its value in gold pieces.
The size of a port determines how much gold can be gained from the sale(which could be as low as 100gp per point of plunder in the smallest thorps). The character who goes ashore to sell the goods may also make Diplomacy check (or Profession: Merchant) to try and haggle for a better price. The DC for this check depends on the community’s size, location and other factors (DM’s discretion) but poor results may reduce the price. Intimidate or Bluff may also be used (in place of Diplomacy) to bully merchants into paying higher prices or lying about the quality of goods, but doing so my have longer-lasting repercussions and so aren’t advised.
Flaunting Plunder grants bonuses on checks to increase Infamy and Disrepute and may also be used at certain points in the story to achieve specific effects.