I hope this fits in Pikes, muskets and flouncy shirts!
I just noticed that the pirate themed Assassin's Creed IV: Black Flag game is on sale for a measly
5€ (75% off) at Steam's current sale. Being a huge, open world adventure set in (loosely historical) 1715, the game is chock full of visual reference material, and the game format allows you to explore towns like Kingston, Havana and Nassau in detailed 3D. So if you have the PC to run it, even if you're not at all interested in the game itself, it's a treasure trove if you're working on a pirate project. I actually bought the art book for the game previously for the same reason, as the game didn't really interest me, but for the price of a few paint bottles or a pint, it's a bargain.
The sale runs until November 30 at
http://store.steampowered.com/app/242050/Here is the trailer and some screenshots of the game in case you're interested: