Harbormaster

Harbormasters managed the ports in Colonial America. They could be hired to build upgrades for ships.

American Revolutionary War
During the American Revolution, the Assassin Ratonhnhaké:ton could purchase the following equipment for his ship the Aquila:


 * Wooden Hull Reinforcements: £13000
 * Iron Hull Reinforcements (requires the above): £25000
 * Extra Cannon: £2500
 * Heat Shot: £19000
 * Grape Shot: £17000
 * Improved Rudder: £11000
 * Piercing Round: £9000
 * Naval Ram: £8000

Reference

 * Assassin's Creed III