Why carrying silver enriched Royal Navy frigate captains

How were Royal Navy captains paid for carrying specie, and where was the South American silver going?

They could receive two percent of cargo carried in the hold and profit from authorized deck cargo, while the silver supported British and East India Company trade with China.

A captain could earn two percent of the value carried in the hold, while goods carried on deck could generate additional private returns shared with the crew. This made specie duty unusually profitable and helped captains recruit and retain skilled sailors. The cargo was not simply being taken to Britain as treasure: silver remained essential for purchasing Chinese goods before the Opium Wars. Personal incentives, crew economics, naval protection, and global commerce reinforced one another on the South American station.