Here is the full list of all 31 Windward achievements. It takes around 40-50 hours to unlock all of the achievements on Windows.
Repair your ship while obscured by fog.
Defeat 100 ships.
Defeat a Pirate Captain.
Completely drive out pirates from a level 9+ region.
Drop Grogolov on top of 3 or more enemies.
Establish a foothold in a region where your faction has no towns.
Hire a follower.
Complete 50 commissions.
Successfully complete a commission to place a Guard Tower near a town.
Achieve a skull kill rating.
Customize your ship's look.
Make a town grow in size.
Open a Sealed Letter.
Complete two consignments at the same time.
Defeat two enemies back to back.
Upgrade your ship.
Do your first trade run.
Defeat 5 pirates.
Defeat an enemy by yourself without taking any damage.
Complete your first commission.
Find and equip your first epic item.
Unlock all ships.
Equip an item that will push any stat above 1000.
Become a true pirate. Arrr!
Opt out of a PvP match by using a White Flag.
Capture a level 9 or higher region in a co-op match.
Sink a pirate captain in a level 39+ region.
Sink another player in PvP.
Drive out pirates from a level 39+ region.
Achieve the Admiral reputation standing with any faction.
Complete the Strange Diagram quest.