Here is my review of the accuracy of Black Sails from season 1. I won't change my review for season 2 until the season is complete. There would only be minor notes to add for season 2 anyhow.

The male characters' clothing is more about the pirate stereotype than turn-of-the-17th-century (turn of the 18th? Is the the one that's coming or going that you call it?) costume. It's not too egregious as they frequently leave off coats and waistcoats, but their trousers are too tight and there should be more shoes than bucket boots. Some coats have collars, which is wrong for 1715, and there should be more coats/waistcoats over shirts. Charles Vane, though, is usually very modern.

This website quotes from a 1706 Admiralty contract about what clothing was available to sailors.

The women, though ... Miranda is the only character they even try for accuracy with, and while I can always see where they're going, they generally fall short of the mark. In large part this is because most of the 18th century knowledge/patterns/premade pieces floating around are 1770s, so many of her things would be decent if the setting were moved forward several decades. Eleanor's tailored vests are completely ahistorical - they're not stays (corsets), and they're not any kind of women's outerwear. She also has a fitted jacket that's more 1870s than anything else.