Wreck the Masts is a Weapon Skill unique to the legendary Norrington's Spyglass. When activated, your pirate's ship receives a buff that causes all outgoing damage to sails and masts to be increased by 40%. This effect has a duration of 15 seconds and takes 45 seconds to recharge.
To use this skill, press '9' on your keyboard, or simply click the Wreck the Masts icon at the bottom of the screen while at the helm of a ship.