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