Here is the full list of all 18 Set Sail achievements.
Choose a cliché pirate name
Find the catalyst for the secret ending
Get the secret ending
Complete the Game
Picked all gender options
Read all the books on the Red Plague
Read all the books in game
Play all the video games
Get everything for free
Respectfully, exhaust all dialogue options with the girls at the school
Defeat three pirates without them calling for backup
Learn all of May's real and fake names
Get your earrings stolen
Gain the most affinity with Behati than the other girls at school
Gain the most affinity with Geraldine than the other girls at school
Gain the most affinity with Fiona than the other girls at school
Gain the most affinity with Astrid than the other girls at school